Synthesis and polymerization of active ester monomers based on 4-vinylbenzoic acid
Abstract Nine active ester monomers based on 4-vinylbenzoic acid have been synthesized. Under free radical polymerization conditions these monomers could successfully be polymerized yielding reactive polymers with molecular weights of around M n = 20.000–50.000 g/mol and molecular weight distributions M w / M n of around or below 2 in good yields. Polymer analogous reactions with amines have been investigated by time-resolved FT-IR spectroscopy and it was found that especially poly(pentafluorophenyl 4-vinylbenzoate) featured a significant reactivity, such that polymer analogous reactions proceeded quantitatively with amines within less than 5 min at 0 °C.
Well-defined carbohydrate-based polymers in calcium carbonate crystallization: Influence of stereochemistry in the polymer side chain on polymorphism and morphology
Abstract In this work we demonstrate the remarkable phase control on the crystallization of calcium carbonate by the stereochemistry of carbohydrate-based polymers. The polymers (poly(2-(2,3,4,6-tetra-O-acetyl-β- d -glucosyloxy)ethyl methacrylate) and poly(2-(2,3,4,6-tetra-O-acetyl-β- d -galactosyloxy)ethyl methacrylate)) have been synthesized from the respective glucose or galactose containing monomers (3 step synthesis) by RAFT polymerization leading to well-defined carbohydrate-based polymers with number averages of the molecular weights (Mw) of 10,000–18,000 g/mol and a dispersities (Đ) from 1.1 to 1.2. For the deprotected polymers we found differences in the phase selection of calcium …
Influence of End Groups on the Stimulus-Responsive Behavior of Poly[oligo(ethylene glycol) methacrylate] in Water
The influence of the chemical structure of both end groups onto the lower critical solution temperature (LCST) of poly[oligo(ethylene glycol) monomethyl ether methacrylate] (POEGMA) in water was systematically investigated. POEGMA of Mn = 3550 g/mol and Mw/Mn = 1.14 prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization was equipped with two different functional end groups in a one-step postpolymerization reaction combining activated esters, functional amines, and functional methane thiosulfonates. As end groups, n-propyl, n-hexadecyl, di(n-octadecyl), poly(ethylene glycol)-550 (PEG), 1H,1H-perfluorononyl, azobenzene, and trimethylethylammonium groups were system…
Synthesis of Functional Inorganic−Organic Hybrid Polymers Based on Poly(silsesquioxanes) and Their Thin Film Properties
New stable and adherent coating materials have been synthesized on the basis of inorganic/organic hybrid polymers. As the inorganic part, different poly(silsesquioxanes) (PSSQ) have been functionalized to act as polymeric chain transfer agents (CTAs) for a reversible addition fragmentation chain transfer polymerization, thereby determining the starting point of a controlled radical polymerization of vinyl-type monomers. Using two different CTAs acrylates, we have successfully polymerized methacrylates and styrene under RAFT polymerization conditions. Different monomers were copolymerized in such an organic block to incorporate multiple functionalities. The variation of the block ratios and …
Two-dimensional self-assembly of disulfide functionalized bis-acylurea: a nanosheet template for gold nanoparticle arrays.
A new functional bis-acylurea molecule allows a two-stage self-organization process. It self-organizes--at first--into 2D nanosheets with disulfide groups at the surface, which act--in the second stage--as a template for gold nanoparticle arrays.
Covalently bonded layer-by-layer assembly of multifunctional thin films based on activated esters.
We demonstrate that chemically stable, multifunctional polymer thin films can be obtained using the layer-by-layer (LbL) deposition based on covalent bonds between adsorbing chains. Poly(pentafluorophenyl-4-vinylbenzoate) (P1) or poly(pentafluorophenylacrylate) (P2) polymers were assembled with poly(allyl amine) (PAAm) to yield LbL multilayer films through amide bond formation by the reaction between activated esters of P1 or P2 and amine groups in PAAm, which was quantitatively monitored by Fourier transform infrared spectroscopy (FT-IR). It was found that the difference in the solubility of P1 and P2 against ethanol, which was used as the solvent for PAAm, during the LbL deposition yields…
Substrate-Independent Stable and Adherent Reactive Surface Coatings and their Conversion with Amines
To create stable, adherent and reactive surface coatings, a hybrid polymer composed of poly(methylsilsesquioxane) (PMSSQ) and poly(pentafluorophenyl acrylate) PFPA with a M n of 32000 g/mol was prepared by a RAFT polymerization procedure. These hybrid polymer has been used for coating experiments. The PFPA part enabled a variable functionalization of the coating afterwards. The stability on various substrates (e.g. glass, PMMA, steel) was tested in an ISO tape test. These reactive surface coatings were modified using different amines, such as amino-terminated PEG, dodecyl amine and N-isopropyl amine. The conversion was analyzed by FT-IR and contact angle measurements.
Superparamagnetic γ-Fe2O3 nanoparticles with tailored functionality for protein separation
Polymer coated superparamagnetic gamma-Fe(2)O(3) nanoparticles were derivatized with a synthetic double-stranded RNA [poly(IC)], a known allosteric activator of the latent (2-5)A synthetase, to separate a single 35 kDa protein from a crude extract which cross reacted with antibodies raised against the sponge enzyme.
Controlled Synthesis of Reactive Polymeric Architectures Using 5-Norbornene-2-carboxylic Acid Pentafluorophenyl Ester
Exo-5-norbornene-2-carboxylic acid pentafluorophenyl ester was synthesized from 5-norbornene-2-carboxylic acid and polymerized by ring-opening metathesis polymerization. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The molecular weight of the polymers was controlled by variation of the monomer to initiator ratio. The precursor polymers reacted quantitatively with primary and secondary amines. Time resolved FT-IR studies at different temperatures of the polymer analogous reactions were performed and rate constants were determined.
Chemical Strategies for the Synthesis of Protein–Polymer Conjugates
Protein-polymer conjugates have achieved tremendous attention in the last few years. The synergistic combination of properties has led to certain advantages in bio-applications. Over the past few years, numerous chemical strategies have been developed to conjugate different synthetic polymers onto proteins, most of which can be summarized within the scope of click-chemistry. Here we highlight conjugation strategies based on available functional groups present on the synthetic polymer and existing groups of proteins from the natural pool. In particular, the chapter organizes the various possible reactions by classes of functional groups present on protein surfaces, deriving from selected ami…
A Versatile Grafting-to Approach for the Bioconjugation of Polymers to Collagen-like Peptides Using an Activated Ester Chain Transfer Agent
DepartmentofMaterials Science and Engineering, University of Delaware, 201DuPont Hall, Newark, Delaware 19716,Received February 24, 2009Revised Manuscript Received April 24, 2009Biohybrid materials consisting of synthetic polymers andbiological moieties have gained more and more interest in therecent years.
Multifunctional polymer-derivatized γ-Fe2O3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins
Abstract Multifunctional polymer-derivatized superparamagnetic iron oxide (γ-Fe2O3) nanoparticles were prepared for biomagnetic separation of histidine-tagged recombinant proteins building up a faster and efficient method for protein separation by making use of their intrinsic magnetic properties. Using polymer bound γ-Fe2O3 nanocrystals, a 6× histidine-tagged recombinant protein (silicatein) with a molecular weight of 24 kDa has been isolated and purified. The supermagnetic iron oxide nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), SQUID and Mossbauer and the polymer functionalization of the γ-Fe2O3 nanocrystals was monitored by UV–vi…
Synthesis of Photoreactive Block Copolymers Based on 1-Iminopyridinium Ylides
Two photoreactive pyridinium ylide containing monomers, {[2-(metacryloyloxy)ethoxy]carbonyl}(pyridinium-1-yl)azanide (M1) and pyridinium-1-yl-(4-vinylbenzoyl)azanide (M2), were synthesized. Both monomers were polymerized under controlled radical polymerization conditions, i.e. reversible addition–fragmentation chain transfer polymerization (M1 and M2) and nitroxide-mediated polymerization (M2). Further block copolymers PMMA-b-PM1 and PS-b-PM2 were successfully synthesized and their molecular weight, Mn, and block ratio could be determined by 1H NMR analysis, thereby opening the synthetic possibilities of photoreactive ylides in block copolymer syntheses.
Poly(4-vinylbenzoyl azide): A New Isocyanato Group Generating Polymer
4-Vinylbenzoyl azide was synthesized from p-vinylbenzoic acid and polymerized by free radical polymerization. The obtained polymer contained acyl azide groups which were thermally transformed to the corresponding isocyanato groups. Reactions on these polymers with ethanol, hydroxyethyl methacrylate and 1-pyrene-butanol proceeded quantitatively. Time-resolved FT-IR studies of the reactions with ethanol were carried out by varying the concentration and temperature. The effect of the solvent polarity on the Curtius rearrangement was investigated.
Synthesis and immobilization of molecular switches onto titaniumdioxide nanowires
Abstract The precursor [Fe III (L)Cl (L = N , N ′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN) 8 ] 4− yields a star shaped nona-nuclear cluster, [Mo IV {(CN)Fe III (L)} 8 ]Cl 4 . This Fe 8 Mo molecule is a high-spin system at room temperature. On cooling to 20 K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mossbauer spectroscopy. This molecule was deposited on TiO 2 nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis s…
Highly Ordered Nanoporous Thin Films from Photocleavable Block Copolymers
Poly(styrene-block-ethylene oxide) with an o-nitrobenzyl ester photocleavable junction (PS-hν-PEO) was synthesized by a combined RAFT polymerization and “click chemistry“ approach and represents the first report utilizing this method for the synthesis of photocleavable block copolymers. After solvent annealing, highly ordered thin films were prepared from PS-hν-PEO. Following a very mild UV exposure and successive washing with water, PS-hν-PEO thin films were transformed into highly ordered nanoporous thin PS films with pore diameters of 15–20 nm and long range ordering (over 2 μm × 2 μm). Afterwards the pores were filled with PDMS by spin-coating in combination with capillary forces. After…
Formation of layered titania and zirconia catalysed by surface-bound silicatein
Silicatein immobilised on self-assembled polymer layers using a histidine-tag chelating anchor group retains its hydrolytical activity for the formation of biosilica, and catalyses the formation of layered arrangements of biotitania and biozirconia.
UCST-type behavior of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in aliphatic alcohols: solvent, co-solvent, molecular weight, and end group dependences
Poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) is shown to possess insoluble–soluble transitions (UCST-type phase behavior) in a large variety of aliphatic alcohols. Samples of different molecular weights ranging from 5 kg mol−1 to 23 kg mol−1 prepared by the RAFT process and featuring different end groups at each end were analyzed by cloud point measurements. Transitions occurred sharply and were fully reversible. The UCST was found to increase with an increasing molecular weight. Hydrophobic (alkyl chain) end groups were found to lower the critical temperature in isopropanol, while rigid aromatic end groups raised the transition temperature. In ternary mixtures of isoprop…
Synthesis and characterization of novel organic–inorganic hybrid block copolymers
Novel organic–inorganic hybrid block copolymers based on poly(methylsilsesquioxanes) (PMSSQs) have been synthesized. Two routes to functionalized PMSSQs are presented and from both atom transfer radical polymerization of methylmethacrylate could be performed. Copolymers with different block ratios have been polymerized and were characterized. In particular, thermal properties were investigated by TGA and the promising thermal decomposition behaviour makes the copolymers potential candidates as pore generators in future nanoporous materials. Additionally, these copolymers were analysed as surface coatings of regular PMMA. Contact angle measurements proved the dramatic effect on the surface p…
PAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale Formation
Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4 center dot 2H(2)O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymerization. The derived copolymers had dispersities of 1.3 and below. The copolymers have then b…
Functional Polymer-Opals from Core-Shell Colloids
Colloidal photonic crystals were prepared from monodisperse core-shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core-shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His-tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric …
Functionalization and patterning of reactive polymer brushes based on surface reversible addition and fragmentation chain transfer polymerization
We present the synthesis of reactive polymer brushes prepared by surface reversible addition–fragmentation chain transfer polymerization of pentafluorophenyl acrylate. The reactive ester moieties can be used to functionalize the polymer brush film with virtually any functionality by simple post-polymerization modification with amines. Dithiobenzoic acid benzyl-(4-ethyltrimethoxylsilyl) ester was used as the surface chain transfer agent (S-CTA) and the anchoring group onto the silicon substrates. Reactive polymer brushes with adjustable molecular weight, high grafting density, and conformal coverage through the grafting-from approach were obtained. Subsequently, the reactive polymer brushes …
Monitoring the formation of biosilica catalysed by histidine-tagged silicatein.
Surface bound silicatein retains its biocatalytic activity, which was demonstrated by monitoring the immobilisation of silicatein using a histidine-tag chelating anchor and the subsequent biosilicification of SiO(2) on surfaces by surface plasmon resonance spectroscopy, atomic force microscopy and scanning electron microscopy.
Die Terminologie von Polymeren mit ionisierbaren oder ionischen Gruppen und von Polymeren, die Ionen enthalten
Reactive Coatings in Glass Capillaries: Preparation of Temperature- and Light-Responsive Surfaces and Accurate Determination of Wettability Switching
Reactive surface coatings based on polysilsesquioxanes: defined adjustment of surface wettability.
We have investigated a generally applicable protocol for a substrate-independent reactive polymer coating that offers interesting possibilities for further molecular tailoring via simple wet chemical derivatization reactions. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylate) hybrid polymers have been synthesized by RAFT polymerization, and stable reactive surface coatings have been prepared by spin-coating on the following substrates: Si, glass, gold, PMMA, PDMS, and steel. These coatings have been used for a defined adjustment of surface wettability by surface-analogous reaction with various amines (e.g., glutamic acid to obtain hydrophilic surfaces (Theta(a) = 18 degrees) or per…
Photoimaging through in-Situ Photopolymerization of Heterobifunctional Mesogenic Compounds in Liquid Crystalline State
A series of heterobifunctional mesogenic biphenyl esters having two different polymerizable groups, i.e., acryl and diacetylene groups, were synthesized and their thermal behaviors and polymerization investigated. All compounds showed enantiotropic transitions. Under POM, highly birefringent focal-conic fan textures appeared on heating and cooling from the isotropic melt. Compounds 6−8 having a butyl spacer between a biphenyl and a diacetylene group exhibited LC phases even at room temperature. The X-ray diffractograms of compounds 6−8 showed a set of reflections in the small-angle region. They consisted of more than three sharp diffraction peaks with d spacings in the ratio of 1:1/2:1/3, s…
Hydrogen peroxide sensors for cellular imaging based on horse radish peroxidase reconstituted on polymer-functionalized TiO2 nanorods
We describe the reconstitution of apo-horse radish peroxidase (apo-HRP) onto TiO2 nanorods functionalized with a multifunctional polymer. After functionalization, the horse radish peroxidase (HRP) functionalized TiO2 nanorods were well dispersible in aqueous solution, catalytically active and biocompatible, and they could be used to quantify and image H2O2 which is a harmful secondary product of cellular metabolism. The shape, size and structure of TiO2 nanorods (anatase) were analyzed by transmission electron microscopy (TEM), high resolution TEM (HRTEM), electron diffraction (ED) and X-ray diffraction (XRD). The surface functionalization, HRP reconstitution and catalytic activity were con…
RAFT polymerization of activated 4-vinylbenzoates
The reversible addition fragmentation chain transfer (RAFT) polymerization of five active ester monomers based on 4-vinylbenzoic acid had been investigated. Pentafluorophenyl 4-vinylbenzoate could be polymerized under RAFT conditions yielding polymers with very good control over molecular weight and narrow molecular weight distributions. Following the synthesis of diblock copolymers consisting of polystyrene, polypentafluorostyrene, poly(4-octylstyrene), or poly(4-acetoxystyrene) as an inert block and poly(pentafluorophenyl 4-vinylbenzoate) as a reactive block was successfully performed. The diblock copolymer poly(pentafluoro styrene)-block-poly(pentafluorophenyl 4-vinylbenzoate) had been a…
Temperature- and light-responsive smart polymer materials.
Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimul…
Surface coatings based on polysilsesquioxanes: Grafting-from approach starting from organic polymers
AbstractPoly(methylsilsesquioxane) (PMSSQ) based hybrid materials are promising candidates to produce substrate-independent stable and adherent surface coatings. Usually these materials are synthesized by controlled radical polymerization from inorganic precursors. The presented synthetic pathway in here demonstrates how to graft PMSSQ networks from an endgroup-functionalized organic polymer and thus enlarges the range of accessible inorganic/organic hybrid coating materials.
Synthesis of Heterotelechelic α,ω Dye-Functionalized Polymer by the RAFT Process and Energy Transfer between the End Groups
The synthesis of a vinyl polymer with two different fluorescent dye end groups using reversible addition-fragmentation chain transfer (RAFT) polymerization is described. Use of a pentafluorophenyl (PFP) activated ester chain transfer agent (CTA) provided a polymer with an R end group that was reactive toward amines and a dithioester ω end group. The R PFP ester was amidated with Oregon Green Cadaverin. This did not harm the ω dithioester, which was subsequently aminolyzed with an excess of n-propylamine in the presence of Texas Red-2-sulfonamidoethyl methanethiosulfonate, resulting in a disulfide bond connecting the second dye to the polymer chain. Excess dyes and side products were removed…
Toward Photopatternable Thin Film Optical Sensors Utilizing Reactive Polyphenylacetylenes
Substituted polyphenylacetylenes featuring reactive pentafluorophenyl (PFP) ester moieties are synthesized. Parts of the reactive PFP groups are then converted with a mono ortho-nitrobenzyl-protected diamine in variable ratios. Thin films are prepared from these copolymers and irradiated with UV light (λ = 365 nm), resulting in crosslinking of the irradiated areas and hence enabling a photopatterning. We found that during the photocrosslinking process, the excess of PFP ester moieties is stable and remained intact, enabling a subsequent post-polymerization modification step with amines. Noteworthy, this subsequent modification with amines results in a dramatically shift in the UV-vis absorp…
Synthesis and characterization of poly(phenylacetylenes) featuring activated ester side groups
Four monomers based on 4-ethynylbenzoic acid have been synthesized, one of those featuring an activated ester. With the metathesis catalytic system WCI 6 /Ph 4 Sn, these acetylenic monomers could successfully be polymerized yielding conjugated polymers with molecular weights of around 10,000 to 15,000 g/mol and molecular weight distributions M w / M n < 2.1. Also the copolymerization of phenylacetylene or methyl 4-ethynylbenzoate with pentafluorophenyl 4-ethynyl-benzoate as reactive unit was conducted. Polymer analogous reactions of the reactive polymers and copolymers with amines have been investigated and it was found that poly(pentafluorophenyl 4-ethynylbenzoate) featured a significant r…
Surface and bulk ordering in thin films of a symmetrical diblock copolymer
Amphiphilic diblock copolymers have the ability to adapt their surface's molecular composition to the hydrophilicity of their environment. In the case of about equal volume fractions of the two polymer blocks, the bulk of these polymers is known to develop a laminar ordering. We report here our investigation of the relationship between bulk ordering and surface morphology/chemical composition in thin films of such an amphiphilic diblock copolymer. Upon annealing in vacuum, the expected lamella ordering in the bulk of the film is observed and we find the morphology of the film surface to be defined by the thickness of the as-deposited film: If the as-deposited thickness matches the height of…
Morphological transformations in a dually thermoresponsive coil-rod-coil bioconjugate.
We report the conformational and assembly behavior of a thermoresponsive triblock biohybrid conjugate under aqueous conditions. The triblock comprises of poly(diethylene glycol methyl ether methacrylate) (PDEGMEMA) conjugated to the ends of a triple-helix forming collagen-like peptide. The circular dichroism (CD) experiment confirms the ability of the collagen-like peptide middle block to assemble as a triple helix in the hybrid conjugate. Above the LCST (∼35 °C), the collapse of the thermoresponsive PDEGMEMA polymer at the ends of the peptide domain resulted in a concomitant increase in the conformational stability of the peptide domain towards thermal denaturation. Upon cooling back, the …
Precise structural investigation of symmetric diblock copolymer thin films with resonant soft X-ray reflectivity
Symmetric diblock copolymers are known to form lamellar structures in the bulk of an organic thin film. Polymer/polymer and polymer/substrate interfaces play a critical role in this application. Here, we report the investigation of multiple buried interfaces by using a novel technique resonant soft X-ray reflectivity which benefits from enhanced contrast between different polymers near the carbon K-edge. This allows us to obtain a precise interface structure. We also present an alternative method to determine optical constants of polymers by fitting X-ray reflectivity of polymers with known structural parameters at specific soft X-ray energies. This approach is compared with the way of obta…
Temperature- and Light-Responsive Polyacrylamides Prepared by a Double Polymer Analogous Reaction of Activated Ester Polymers
Two different series of polyacrylamides containing different amounts of salicylideneaniline moieties have been synthesized via a double polymer analogous reaction of poly(pentafluorophenyl acrylate) (PPFPA). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in aqueous solution, which was dependent on (i) the amount of incorporated chromophoric salicylideneaniline groups and (ii) the isomerization state of the respective salicylideneaniline group. Higher LCST values were measured for UV-irradiated solutions of the copolymers in comparison to the nonirradiated copolymer solutions. A maximum difference in the LCST of up to 13 °C was found for poly(N-cycloprop…
Liquid Crystalline Phases from Polymer-Functionalized TiO2 Nanorods
Versatile Synthesis of Functional Gold Nanoparticles: Grafting Polymers From and Onto
Functionalized gold nanoparticles have been prepared in an organic solvent by a two-phase reduction method in ethyl acetate and water using bis(6-hydroxyhexyl) disulfide bis(2-bromoisobutyl) ester, bis(6-acetyloxyhexyl) disulfide, and bis(5-carboxypentyl) disulfide bis(pentafluorophenyl) ester as stabilizing ligands. This procedure features the advantages that no phase transfer agent was necessary during the preparation of the gold nanoparticles and that the reducing conditions were mild enough to utilize functional disulfide ligands. The obtained gold nanoparticles with typical sizes between 2 and 5 nm could be precipitated and redispersed without any irreversible aggregation. Using these nanop…
Surface Coatings Based on Polysilsesquioxanes: Solution-Processible Smooth Hole-Injection Layers for Optoelectronic Applications
Optoelectronic devices usually consist of a transparent conductive oxide (TCO) as one electrode. Interfacial engineering between the TCO electrode and the overlying organic layers is an important method for tuning device performance. We introduce poly(methylsilsesquioxane)-poly(N,N-di-4-methylphenylamino styrene) (PMSSQ-PTPA) as a potential hole-injection layer forming material. Spin-coating and thermally induced crosslinking resulted in an effective planarization of the anode interface. HOMO level (-5.6 eV) and hole mobility (1 × 10(-6) cm(2) · Vs(-1) ) of the film on ITO substrates were measured by cyclovoltammetry and time-of-flight measurement demonstrating the hole injection capabili…
Influence of Binding-Site Density in Wet Bioadhesion
Post-Polymerization Modification
The synthesis of functional polymers has been enriched dramatically by post-polymerization modifications. Even though it represents a synthetically very appealing approach, different synthetic concepts of organic reactions are utilized in polymer science for the synthesis of architecturally well-defined multifunctional polymers. The different classes of reactions that provide the synthetic polymer chemist with tools of unprecedented precision, thereby opening the doors for materials synthesis in an interdisciplinary world, will be summarized.
Nanotube Friendly Poly(N-isopropylacrylamide).
Poly(N-ispropylacrylamide) [PNIPAM] is a widely studied polymer for use in biological applications due to its lower critical solution temperature (LCST) being so close to the human body temperature. Unfortunately, attempts to combine carbon nanotubes (CNTs) with PNIPAM have been unsuccessful due to poor interactions between these two materials. In this work, a PNIPAM copolymer with 1 mol-% pyrene side group [p-PNIPAM] was used to produce a thermoresponsive polymer capable of stabilizing both single and multi-walled carbon nanotubes (MWNTs) in water. The presence of pyrene in the polymer chain lowers the LCST less than 4 °C and the interaction with nanotubes does not show any influence on LC…
Improvement of solubility and biocompatibility of MnO based nanoparticles in aqueous solutions
ABSTRACTMnO nanoparticles were surface modified using two different multifunctional polymers. By introducing a PEG group, the long term stability, MRI applicability and sterile filtration could be greatly improved. Furthermore, PEGylated MnO NPs were less toxic compared to non-PEGylated NPs. The results suggest that these nanoparticles are suitable for in vivo applications.
dsRNA-functionalized multifunctional gamma-Fe2O3 nanocrystals: a tool for targeting cell surface receptors.
Hierarchical Assembly of TiO2 Nanoparticles on WS2 Nanotubes Achieved Through Multifunctional Polymeric Ligands
Thefunctionalization of nanotubes is required in order to bene-fit from their outstanding properties, as any application inmaterials and devices is hindered by processing and manipu-lation difficulties. Only the attachment of appropriate chem-ical functionalities on the nanotube surface allows tailoringof the properties for the respective applications. As an ex-ample, the enhancement of the nanotube solubility is onemajor task since most pristine nanotubes are insoluble inboth water and organic solvents. Thus, the improvement ofthe solubility by chemical functionalization is an importantconcept for synthetic chemists and materials scientists. Tai-loring of the surface chemical bonds might a…
Temperature-Responsive Surface Coatings Based on Poly(methylsilsesquioxane)-hybrid Polymers
The present paper presents a new method to build up temperature-responsive surfaces. First a poly(silsesquioxane)-block-poly(N-isopropyl-acrylamide) (PMSSQ-b-PNIPAM) was successfully synthesized using RAFT polymerization. Spin-coating or dip-coating of PMSSQ-b-PNIPAM onto glass surfaces resulted in temperature-responsive surfaces. Surface ATR FT-IR measurements proofed the successful surface modification using PMSSQ-b-PNIPAM. IR fine structures of PNIPAM and PMSSQ could be assigned, respectively. In capillary rise experiments a change of the meniscus height measured at temperatures below or above LCST was observed, indicating a different wetting behavior. Thus, a simple spin- or dip-coating…
Synthesis of CO2-responsive polymers by post-polymerization modification
Abstract We describe a general method to synthesize a double responsive polymer, exhibiting a temperature and CO 2 responsive behavior. The polymer derived from a controlled radical polymerization technique of pentafluorophenyl acrylate (PFPA), followed by a sequential post-polymerization modification of a CO 2 responsive- and thermo-responsive amines. Utilizing this approach three double responsive copolymers were synthesized, poly(3- N′,N′ -dimethylaminopropyl acrylamide- co - N -isopropyl acrylamide) (poly(DMPA- co -NIPAM)), poly( L -Arginine methyl ester acrylamide- co - N -isopropyl acrylamide) (poly(AME- co -NIPAM)) and poly( L -Arginine methyl ester acrylamide- co - N -cyclopropyl ac…
Enzyme-Mediated Deposition of a TiO2Coating onto Biofunctionalized WS2 Chalcogenide Nanotubes
A chemically specific and facile method for the biofunctionalization of WS2 nanotubes (NT-WS2) is reported. The covalent modification strategy is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the surface binding to NT-WS2 and simultaneously as an anchor group for the binding of His-tagged proteins to the polymer backbone. The polymer functionalized WS2 nanotubes can be solubilized either in water or organic solvents; they are stable for at least one week. The probes were characterized by FT-IR and UV-vis spectroscopy. The immobilization of silicatein, a hydrolytic protein encountered in marine sponges, was visualized by scanning force micr…
Sequential conversion of orthogonally functionalized diblock copolymers based on pentafluorophenyl esters
Statistic and block copolymers exhibiting activated ester side groups were synthesized by reversible addition-fragmentation chain transfer polymerization in the presence of cumyl dithiobenzoate, benzyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Pentafluorophenyl methacrylate and pentafluorophenyl 4-vinylbenzoate were used to enable a sequential functionalization of the obtained copolymers by conversion of the activated esters with different amines. 1H NMR spectroscopy, 19F NMR spectroscopy, and FTIR spectroscopy showed the successful step-by-step conversion of the different activated esters by aniline followed by aliphatic amines, thereby r…
Toward mass producible ordered bulk heterojunction organic photovoltaic devices.
A strategy to fabricate nanostructured poly(3-hexylthiophene) (P3HT) films for organic photovoltaic (OPV) cells by a direct transfer method from a reusable soft replica mold is presented. The flexible polyfluoropolyether (PFPE) replica mold allows low-pressure and low- temperature process condition for the successful transfer of nanostructured P3HT films onto PEDOT/PSS-coated ITO substrates. To reduce the fabrication cost of masters in large area, we employed well-ordered anodic aluminum oxide (AAO) as a template. Also, we provide a method to fabricate reversed nanostructures by exploiting the self-replication of replica molds. The concept of the transfer method in low temperature with a fl…
UV-tunable upper critical solution temperature behavior of azobenzene containing poly(methyl methacrylate) in aqueous ethanol
A series of azobenzene containing copolymers were synthesized by post-modification of poly(methyl methacrylate-co-pentafluorophenyl methacrylate) with an amine-functionalized azobenzene. Light- and thermo-responsive behavior of these copolymers was investigated in ethanol–water solvent mixtures with various amounts of ethanol. The upper critical solution temperature (UCST) of the polymer solutions, resulting from the poly(methyl methacrylate), was found to be highly tunable by the substitution degree of the copolymers as well as the ethanol content of the solvent mixture. In addition, the copolymers are light responsive based on the cis–trans isomerization of the azobenzene group under UV i…
Macromol. Chem. Phys. 10/2009
Reactive thiol-ene emulsion-templated porous polymers incorporating pentafluorophenyl acrylate
Abstract Highly porous polymers (polyHIPEs) incorporating activated esters have been prepared by photopolymerisation of high internal phase emulsions (HIPEs) containing pentafluorophenyl acrylate (PFPA) in the monomer phase. The resulting materials have nominal porosity of 80% and a well-defined, interconnected pore morphology with average pore diameters ranging from 30 to 50 μm. PFPA could be added at up to 50 wt% of the monomer phase without destabilising the HIPE noticeably, however analysis of the polyHIPE materials revealed that only around half of this was incorporated into the final porous materials. The pentafluorophenyl groups were shown to be reactive towards a range of amines (tr…
Synthesis of Processable Inorganic‐Organic Hybrid Polymers Based on Poly(silsesquioxanes): Grafting from Polymerization Using ATRP
Inorganic-organic hybrid polymers have been synthesized utilizing atom transfer radical polymerization (ATRP) from a functionalized poly(methylsilsesquioxane) (PMSSQ) macroinitiator. Different polymeric ATRP initiators were prepared by co-condensation of functionalized trichlorosilanes with methyltrimethoxysilane. Various vinyl monomers have been successfully grafted from these macroinitiators, demonstrating a highly variable synthetic concept, which offers the chance to synthesize a wide spectrum of inorganic-organic hybrid polymers. All synthesized polymers were soluble in various organic solvents. Spin-coating these hybrid materials onto various substrates could produce stable and adhere…
Template-Based Fabrication of Nanometer-Scaled Actuators from Liquid-Crystalline Elastomers
Overcoming the Insolubility of Molybdenum Disulfide Nanoparticles through a High Degree of Sidewall Functionalization Using Polymeric Chelating Ligands
From Single Molecules to Nanoscopically Structured Functional Materials: Au Nanocrystal Growth on TiO2 Nanowires Controlled by Surface-Bound Silicatein
Au@MnO-“Nanoblumen” - Hybrid-Nanokomposite zur selektiven dualen Funktionalisierung und Bildgebung
In j ngster Vergangenheit hat das Interesse f r die Entwicklung von Hybrid-Nanostrukturen, die sich aus verschiedenen Materialien zusammensetzen, in erheblichem Mase zugenommen. Es wurde berichtet, dass die Zusammenf hrung verschiedener Nanomaterialien, die ihrerseits spezifische optische, magnetische oder elektronische Eigenschaften aufweisen, zu Kompositen aus mehreren dieser Komponenten, deren individuelle Eigenschaften ver ndern oder sogar verbessern k nnen. Durch gezielte Optimierung der Struktur und der Grenzfl chenwechselwirkung innerhalb der Nanokomposite k nnte eine breite Basis f r zuk nftige Technologien geschaffen werden, beispielweise f r die synchrone Biomarkierung, Proteintre…
Hetero-Telechelic Dye-Labeled Polymer for Nanoparticle Decoration
The synthesis of poly(methyl methacrylate) (PMMA) exhibiting one fluorescent dye (Texas Red) and one methyl disulfide end group is described. It is shown that the latter end group enabled the exchange of both oleic amine on gold nanoparticles (AuNP) and of oleic acid on CdSe/ZnS quantum dots (QD), allowing for a phase transfer of both types of nanoparticles (NP) from hexane into dimethylformamide due to the solubility provided by the PMMA chains. For AuNP, a fluorescence quenching of the dye was found due to fluorescence resonance energy transfer (FRET) from the dye to the AuNP, while QDs caused a fluorescence enhancement by FRET from the QD to the attached dyes. Due to the hetero-telecheli…
A Method for Obtaining Defined End Groups of Polymethacrylates Prepared by the RAFT Process during Aminolysis
Macromolecules is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Communication to the Editor A Method for Obtaining Defined End Groups of Polymethacrylates Prepared by the RAFT Process during Aminolysis Peter J. Roth, Daniel Kessler, Rudolf Zentel, and Patrick Theato Macromolecules, 2008, 41 (22), 8316-8319 • Publication Date (Web): 01 November 2008 Downloaded from http://pubs.acs.org on November 19, 2008
Nanoporous Thin Films Based on Polylactide-Grafted Norbornene Copolymers
Thermally stable vinyl polymerized polynorbornene (PNB) is one of the challenging materials in porous low dielectric films for packaging applications. Nanoporous PNB thin films were obtained with poly(d,l-lactide) (PLA)-grafted norbornene copolymers. Thermally labile PLA chains act as pore generators in PNB films. Thermally stable PNB main chains were synthesized by Pd-catalyzed vinyl polymerization and PLA side chains were grafted onto the PNB main chains by ring opening polymerization. The brittle and poor processible properties of PNB could easily be controlled by the copolymerization with norbornene derivatives. In thin films, the PLA chains were found to thermally decompose at about 25…
Redox active polymers with phenothiazine moieties for nanoscale patterning via conductive scanning force microscopy
Redox active polymers with phenothiazine moieties have been synthesized by Atomic Transfer Radical Polymerization (ATRP). These novel polymers reveal bistable behaviour upon application of a bias potential above the oxidation threshold value. Using conductive Scanning Force Microscopy, two distinguishable conductivity levels were induced on a nanoscale level. These levels were related to a high conducting “On” and a low conducting “Off” state. The “On” state is generated by the oxidation of the phenothiazine side chains to form stable phenothiazine radical cations. The formation and stability of the radical sites was examined by cyclic voltammetry, electron spin resonance and optical spectr…
Polyelectrolytes on block copolymer surfaces
Soft lithography and properties of amphiphilic block copolymers are combined in a new technique for the generation of patterned substrates, which can be used in different ways as templates for further processing. In these processing steps the deposition of polyelectrolytes, metals and grafting from polymerizations are used for the construction of different structures.
Reactive nanorods based on activated esterpolymers: a versatile template-assisted approach for the fabrication of functional nanorods
A new route for the fabrication of polymeric nanorods with functional moieties via post-modification of reactive nanorods is described. To this end reactive nanorods with a homogenous and narrow size distribution were fabricated by utilizing an anodic aluminium oxide (AAO) template-assisted approach. The nanorods are based on activated pentafluorophenyl esters, to enable quantitative post-modification with amines under very mild reaction conditions yielding the corresponding functionalized amide. Post-modification with fluorescent dyes as well as the conversion into well-dispersed rod-shaped poly(N-isopropylacrylamide) (PNIPAM) hydrogels that exhibit a thermal-responsive phase transition wa…
Chemical Mimicry: Hierarchical 1D TiO2@ZrO2 Core−Shell Structures Reminiscent of Sponge Spicules by the Synergistic Effect of Silicatein-α and Silintaphin-1
In nature, mineralization of hard tissues occurs due to the synergistic effect of components present in the organic matrix of these tissues, with templating and catalytic effects. In Suberites domuncula, a well-studied example of the class of demosponges, silica formation is mediated and templated by an axial proteinaceous filament with silicatein-α, one of the main components. But so far, the effect of other organic constituents from the proteinaceous filament on the catalytic effect of silicatein-α has not been studied in detail. Here we describe the synthesis of core-shell TiO(2)@SiO(2) and TiO(2)@ZrO(2) nanofibers via grafting of silicatein-α onto a TiO(2) nanowire backbone followed by …
Temperature and light sensitive copolymers containing azobenzene moieties prepared via a polymer analogous reaction
Abstract Four different series of polyacrylamides containing different amounts of azobenzene moieties have been synthesized via a polymer analogous reaction of poly(pentafluorophenylacrylate) (PPFPA). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in aqueous solution, which was dependent on (i) the amount of incorporated chromophoric azobenzene groups and (ii) the isomerization state of the respective azobenzene group. Higher LCST values were measured for UV-irradiated solutions of the copolymers in comparison to the non-irradiated copolymer solutions. A maximum difference in the LCST of up to 7 °C was found for the copolymer poly(N,N-dimethylacrylamide…
Definitionen von Grundbegriffen mit Bezug zu Polymerreaktionen und zu funktionellen polymeren Materialien
Hier werden die Ausdrucke definiert, die im Bereich von Polymerreaktionen und funktionellen Polymeren am gelaufigsten sind. Dabei wurden nur Begriffe aufgenommen, die fur Polymersysteme spezifisch sind. Die Zusammenstellung ist in drei Abschnitte unterteilt: Im ersten werden die Begriffe definiert, die sich auf Polymerreaktionen beziehen. Die Namen spezifischer chemischer Reaktionen wurden nicht aufgenommen, auch nicht in Fallen, in denen die Reaktionen wichtig fur das Gebiet der Polymerreaktionen sind. Im zweiten Abschnitt werden Begriffe zu polymeren Reaktanten und reaktiven polymeren Materialien definiert, und im dritten Begriffe, die funktionelle polymere Materialien beschreiben.
Modular approach toward bioactive fiber meshes carrying oligosaccharides
A modular strategy toward (bio)functional nanofiber meshes by electrospinning is described. In contrast to commonly established, multistep protocols or complex spinning setups, a straightforward single-step procedure is investigated to obtain polymer nanofibers with pentafluorophenyl (Pfp)-activated esters on the surface. The aim was to electrospin, for the first time, poly(pentafluorophenyl methacrylate) (PPfpMA) and PPfpMA/poly(epsilon-caprolactone) (PCL) blends, resulting in reactive nanofibers with fiber surfaces that can be functionalized with suitable bioactive entities. While PPfpMA fibers are brittle the spinning of PCL/PPfpMA blends leads to improved mechanical stability of the obt…
dsRNA-funktionalisierte γ-Fe2O3-Nanokristalle: ein Instrument zur gezielten Adressierung von Rezeptoren an der Zelloberfläche
Polymerization of an activated ester monomer based on 4-vinylsulfonic acid and its polymer analogous reaction
Homopolymers containing sulfonic ester side groups were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization utilizing benzyl dithiobenzoate, cumyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Likewise diblock copolymers containing poly(styrene), poly(octylstyrene) and poly(pentafluorostyrene) as the second block were synthesized. Additionally, nitroxide mediated polymerization (NMP) was investigated for the synthesis of a homopolymer as well as for a diblock copolymer. Furthermore, the post-polymerization functionalization with various amines to yield the respective sulfonamides was conducted. The conversion …
Facile Synthesis of Fluorescent Polymer Nanoparticles by Covalent Modification-Nanoprecipitation of Amine-Reactive Ester Polymers
Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers,…
Versatile Responsive Surfaces via Hybrid Polymers Containing Acetal Side Groups
Two hybrid polymers, poly(methylsilsesquioxane)-poly(2,2-diethoxyethyl acrylate) and poly-(methylsilsesquioxane)-poly(1,3-dioxolan-2-ylmethyl acrylate), were synthesized and used for preparation of stable surface coatings. Their acetal side groups could be functionalized via solution-dipping with different primary amines and hydroxylamines after acidic deprotection and thus allowed for flexible modification of the surface hydrophilicity. Functionalization with a thermo-responsive polymer resulted in a thermo-responsive surface with temperature-dependent contact angles. Further, the two types of acetals showed different stability toward acidic treatment and could be addressed independently.
Au@MnO nanoflowers: hybrid nanocomposites for selective dual functionalization and imaging.
Recently, the development of hybrid nanostructures consisting of various materials has attracted considerable interest. The assembly of different nanomaterials with specific optical, magnetic, or electronic properties to multicomponent composites can change and even enhance the properties of the individual constituents. Specifically tuning the structure and interface interactions within the nanocomposites has resulted in novel platforms of materials that may lead the way to various future technologies, such as synchronous biolabeling, protein separation and detection, heterogeneous catalysis, and multimodal imaging in biomedicine. Of the various kinds of nanomaterials, gold nanorods show an…
Mapping of local conductivity variations on fragile nanopillar arrays by scanning conductive torsion mode microscopy.
A gentle method that combines torsion mode topography imaging with conductive scanning force microscopy is presented. By applying an electrical bias voltage between tip and sample surface, changes in the local sample conductivity can be mapped. The topography and local conductivity variations on fragile free-standing nanopillar arrays were investigated. These samples were fabricated by an anodized aluminum oxide template process using a thermally cross-linked triphenylamine-derivate semicondcutor. The nanoscale characterization method is shown to be nondestructive. Individual nanopillars were clearly resolved in topography and current images that were recorded simultaneously. Local current−…
Reactive Surface Coatings Based on Polysilsesquioxanes: Controlled Functionalization for Specific Protein Immobilization
The key designing in reliable biosensors is the preparation of thin films in which biomolecular functions may be immobilized and addressed in a controlled and reproducible manner. This requires the controlled preparation of specific binding sites on planar surfaces. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylates) (PMSSQ-PFPA) are promising materials to produce stable and adherent thin reactive coatings on various substrates. Those reactive surface coatings could be applied onto various materials, for example, gold, polycarbonate (PC), poly(tetrafluoroethylene) (PTFE), and glass. By dipping those substrates in a solution of a desired amine, specific binding sites for protein ads…
Modular approach towards multi-functional surfaces with adjustable and dual-responsive wettability using a hybrid polymer toolbox
Poly(methylsilsesquioxane)-based hybrid polymers carrying orthogonally reactive moieties demonstrate an effective modular approach to creating multi-reactive surface coatings. By a sequential surface-analogous reaction different functions could be immobilized in a defined ratio, resulting in dual- or triple-functionalized surfaces.
Double Thermoresponsive Block Copolymers Featuring a Biotin End Group
A poly(oligo(ethylene glycol) monomethyl ether methacrylate)-block-poly(N-isopropyl methacrylamide) (POEGMA-b-PNIPMAM) block copolymer with a biotin end group on the PNIPMAM block as a biotarget was synthesized as a model system for temperature-controlled polymer immobilization. The synthesis was based on RAFT polymerization followed by postpolymerization modification of an activated ester precursor block and an exchange of the dithioester end group within one step. NMR, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and turbidimetry measurements were performed to investigate the stimulus-responsive properties. The double thermoresponsive POEGMA-b-PNIPMAM with biot…
The Next 100 Years of Polymer Science
International audience; The year 2020 marks the 100th anniversary of the first article on poly merization, published by Hermann Staudinger. It is Staudinger who realized that polymers consist of long chains of covalently linked building blocks. Polymers have had a tremendous impact on the society ever since this initial publication. People live in a world that is almost impossible to imagine without synthetic polymers. But what does the future hold for polymer science? In this article, the editors and advisory board of Macromolecular Chemistry and Physics reflect on this question.
Thermo- and Light-Responsive Polymers Containing Photoswitchable Azobenzene End Groups
Telechelic thermo- and light-responsive polymers based on poly(oligo(ethylene glycol) methyl ether methacrylate) P(OEGMA) with azobenzene functionalities at the end groups were synthesized. In a reversible addition−fragmentation chain transfer (RAFT) polymerization using a functionalized chain transfer agent (CTA) containing a pentafluorophenyl (PFP) activated ester, oligo(ethylene glycol) methyl ether methacrylate (OEGMA, Mn ∼ 300 g mol−1) could successfully be polymerized with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from this CTA possessed an activated ester at the α-end of the polymer chain as well as a dithio…
From Defined Reactive Diblock Copolymers to Functional HPMA-Based Self-Assembled Nanoaggregates
This paper describes the synthesis of functional amphiphilic poly( N-(2-hydroxypropyl) methacrylamide)-block-poly(lauryl methacrylate) copolymers by RAFT polymerization via the intermediate step of activated ester block copolymers (pentafluoro-phenyl methacrylate). Block copolymers with molecular weights from 12000-28000 g/mol and PDIs of about 1.2 have been obtained. The amphiphilic diblock copolymers form stable super structures (nanoaggregates) by self-organization in aqueous solution. The diameters of these particles are between 100 and 200 nm and depend directly on the molecular weight of the block copolymer. Furthermore, we investigated the impact of these nanoaggregates on cell viabi…
Controlled synthesis of poly(acetone oxime acrylate) as a new reactive polymer: Stimuli-responsive reactive copolymers
Abstract Acetone oxime acrylate has been synthesized as a new active ester monomer. Free radical polymerization yielded a reactive polymer soluble in various organic solvents, such as chloroform, dioxane, DMSO, acetone, methanol, dichloromethane, DMF, and ethanol. Controlled radical polymerization of acetone oxime acrylate was successfully conducted using the RAFT, NMP and Iniferter method. Partly polymer analogous reaction with N-isopropylamine resulted in the reactive copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate), which featured a lower critical solution temperature (LCST) of 61 °C in water. Further, the reactivity of the copolymer was exemplary proven by complete reacti…
Growth of fibrous aggregates of silica nanoparticles: Fibre growth by mimicking the biogenic silica patterning processes
We describe the self-assembly of discrete SiO2 nanofibers via grafting of silicatein side chains to a polymer backbone. The covalent binding of silicatein to the backbone of the polymer is based on the affinity of the nitrilotriacetic acid (NTA) side chain, which serves as a ligand for the immobilization of His-tagged silicatein. The surface charge and the bulkiness of the protein moieties prevent the entropically favoured coil formation of the polymer and force it to adopt an open chain structure after hydrolysis of the silica precursors. The probes were characterized by scanning force microscopy (SFM) and optical light microscopy. Surface complexation of the resulting silica nanoparticles…
α,ω-Functionalized poly-N-isopropylacrylamides: controlling the surface activity for vesicle adsorption by temperature
The synthesis of alpha,omega-end-functionalized copolymers of N-isopropylacrylamide and N-(3-dimethylaminopropyl)acrylamide was performed. Monomer ratios of 100:0, 96:4, and 81:19 were investigated. The lower critical solution temperature (LCST) of these polymers was determined by cloud-point measurements and by microcalorimetric measurements. The LCST increased from 32 over 37 to 47 degrees C as the hydrophobicity increased with increasing amount of comonomer N-(3-dimethylaminopropyl)acrylamide. The polymers could successfully be adsorbed onto gold surfaces. Finally, vesicle adsorption onto these self-assembled polymer films on flat gold surfaces was investigated as the vesicle solution te…
Fabrication of a Silica Coating on Magnetic γ-Fe2O3 Nanoparticles by an Immobilized Enzyme
Silicatein, a hydrolytic protein encountered in marine sponges, was immobilized on maghemite (γ-Fe2O3) nanoparticles that were surface functionalized with a reactive mulfunctional polymer. This polymer carries an anchor group based on dopamine which is capable of binding to the γ-Fe2O3 surface and a reactive functional group which allows binding of various biomolecules onto inorganic nanoparticles. This functional nitrilotriacetic acid (NTA) group allows immobilization of His-tagged silicatein on the surface of the γ-Fe2O3 nanoparticles. The surface-bound protein retains its native hydrolytic activity to catalyze formation of silica through copolymerization of alkoxysilanes Si(OR)4. Functio…
Versatile ω-end group functionalization of RAFT polymers using functional methane thiosulfonates
Five different polymers, poly[methyl methacrylate] (PMMA), poly[lauryl methacrylate] (PLMA), poly[diethylene glycol methacrylate] (PDEGMA), poly[N-iso-propylacrylamide] (PNIPA), and poly[styrene] (PS) prepared by the RAFT process and thus terminated with dithioesters were aminolyzed in the presence of S-3-butynyl methane thiosulfonate (MTS), which was synthesized in two steps. Analysis of the polymers by 2D NMR, UV–vis absorbance, and gel permeation chromatogra-phy revealed them to quantitatively carry acetylene end groups connected with disul-fide bridges, indicating that functional MTS reagents can be employed for end group functionalization of RAFT polymers. This versatile method is of ad…
Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells
Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced …
PNIPAM Copolymers Containing Light-Responsive Chromophores: A Method Toward Molecular Logic Gates
A series of thermo-responsive PNIPAM copolymers containing different amounts of fulgimide moieties has been synthesized via a polymer analogous reaction of poly(pentafluorophenyl acrylate). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in water, which was only weakly dependent on the amount of incorporated chromophoric fulgimide groups. The copolymers showed a photocyclization of the fulgimide side groups upon irradiation with UV-light accompanied with a color change. The closed form of the chromophore had a halftime of 136 min for the visible reisomerization and did not affect the LCST of the polymer. This led to the realization of a logic "NOT A" for…
Multi-stimuli responsive polymers – the all-in-one talents
Stimuli-responsive polymers have gained increasing attention, which is attributed to the manifold applications they can be used for. Several years' intensive research was invested in stimuli-responsive polymers. Their stimuli-responsiveness led not only to novel responsive groups, which enabled the translation of an external physical impact into a change of a material property, but also to polymers that are equipped with more than one responsive group. The integration of several responsive moieties within one polymer yields smart polymers exhibiting complex responsive behaviour of the polymers. This review summarises recent developments in the area of multi-stimuli responsive polymers, layi…
Reactive surface coatings based on polysilsesquioxanes: universal method toward light-responsive surfaces.
Reactive surface coatings were used as an ideal precursor coating for the fabrication of three different photoswitchable surface coatings in parallel. Different light-responsive moieties, such as azobenzene, salicylideneaniline, and spiropyran, were immobilized on glass, polycarbonate, and steel surfaces. Independent from the underlying substrate, wettability could be switched reversibly by UV irradiation. The maximum switching range was obtained after functionalization of the reactive coating with spiropyran, resulting in a contact angle difference between the two isomeric states of almost 30°.
Comparison of Hybrid Blends for Solar Cell Application
In blended hybrid systems distinct micro- or nanostructured materials can be formed by phase separation. Network structures of particles or rods in a polymer matrix can be developed via self-assembly. We use this blending approach to compare active materials for application in solar cell devices. Blends were fabricated from either poly(hexylthiophene) P3HT or poly(triphenylamine) PTPA mixed with nanocrystalline TiO 2 rods. In this manner, we compare two different hole conducting polymers in their performance in photovoltaic devices, while experimental conditions are kept identical. We find that the choice of solvent and photovoltaic characterization conducted in inert atmosphere is of impor…
Multi-responsive copolymers: using thermo-, light- and redox stimuli as three independent inputs towards polymeric information processing
We report on triple responsive polymers, exhibiting a distinct and reversible lower critical solution temperature in water that can be altered by light and redox stimuli, and we suggest their evaluation for molecular information processing.
Template-assisted fabrication of free-standing nanorod arrays of a hole-conducting cross-linked triphenylamine derivative: toward ordered bulk-heterojunction solar cells.
Free-standing nanorod arrays of a thermally cross-linked semiconducting triphenylamine were fabricated on conductive ITO/glass substrates via an anodic aluminum oxide (AAO) template-assisted approach. By using a solution wetting method combined with a subsequent thermal imprinting step to fill the nanoporous structure of the template with a cross-linkable triphenylamine derivative, a polymeric replication of the AAO was obtained after thermal curing and selective removal of the template. To obtain well-aligned and free-standing nanorod arrays, aggregation and collapse of the nanorods were prevented by optimizing their aspect ratio and applying a freeze-drying technique to remove the aqueous…
IF-ReS2 with Covalently Linked Porphyrin Antennae
The preparation of inorganic and organic hybrid materials, of metals or semiconductor systems which are functionalized with functional molecules to fabricate devices — nanotechnology — is currently an area of intense activity in both fundamental science and applied science on an international scale. Principally, nanotechnology aims at manipulating atoms, molecules, and nanosize particles in a precise and controlled manner in order to build materials with a fundamentally new organization and novel properties. The embryonic stage of nanotechnology is atomic assembly, whereas the mature form of nanotechnology will be molecular assembly to make nano-building blocks for the design of nanocomposi…
Synthesis of well-defined polymeric activated esters
Monomers bearing an activated ester group can be polymerized under various controlled polymerization techniques, such as ATRP, NMP, RAFT polymerization, or ROMP. Combining the functionalization of polymers via polymeric activated esters with these controlled polymerization techniques generate possibilities to realize highly functionalized polymer architectures. Within this highlight two different research areas of activated esters in polymer science will be discussed: (i) the preparation of defined reactive polymer architectures by controlled polymerization techniques and (ii) the preparation of defined reactive thin films. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6…
One is Enough: Influencing Polymer Properties with a Single Chromophoric Unit
1) Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstrasse 45, D-‐20146 Hamburg, Germany 2) WCU program of C2E2, School of Chemical and Biological, Engineering, College of Engineering, Seoul National University, Seoul, Korea Designing a polymer usually involves the incorporation of multiple functional units into a polymer chain, which mutually determine the polymer properties. By combining various functional units, a myriad of polymer properties can be fine-‐ tuned. Classical polymer chemistry teaches us that a single functional group -‐-‐ in particular the end-‐group of a polymer chain -‐-‐ does not contribute to the polymer properties, as is indee…
Synthesis of pentafluorophenyl(meth)acrylate polymers: New precursor polymers for the synthesis of multifunctional materials
Pentafluorophenyl acrylate and -methacrylate were polymerized using AIBN as a thermal initiator. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The reactivity of poly(pentafluorophenylacrylate) and poly(pentafluorophenylmethacrylate) towards primary and secondary amines, as well as alcohols was investigated in a quantitative way. Both poly(active esters) reacted satisfactorily with aliphatic primary and secondary amines but only low conversion was found in the case of aromatic amines. Conversions of only 30% were reached when poly(pentafluorophenylacrylate) was treated with one equivalent of alcohol under base c…
Temperature dependence of surface reorganization characteristics of amphiphilic block copolymer in air and in water studied by scanning force microscopy
We have investigated the surface reorganization characteristics of a novel amphiphilic diblock copolymer, poly(acetic acid-2-(2-(4-vinyl-phenoxy)-ethoxy)-ethylester)-block-polystyrene (PAEES-b-PS), in response to varying interfaces from air to water and vice-versa at various temperatures. The surface reorganization characteristics of the block copolymer films was monitored by scanning force microscopy, in order to delineate the kinetically controlled morphological process of surface reorganization of a diblock copolymer, with a particular emphasis on the phase contrast signal which allowed the determination of local composition patterns of PAEES-b-PS at the surface. Upon heating a water-an…
Synthesis of Reactive Telechelic Polymers Based on Pentafluorophenyl Esters
A diazo initiator and a chain transfer agent (CTA), both containing a pentafluorophenyl (PFP) activated ester, were synthesized. In a RAFT polymerization using the functionalized chain transfer agent (PFPCTA), methyl methacrylate (MMA), diethylene glycol monomethyl ether methacrylate (DEGMA), poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), and lauryl methacrylate (LMA) could successfully be polymerized into homopolymers and diblock copolymers with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from the PFP-CTA possessed an activated ester at the R-end of the polymer chain, which could be reacted with amines…
Fabrication of Chemically Tunable, Hierarchically Branched Polymeric Nanostructures by Multi-branched Anodic Aluminum Oxide Templates
In this paper, a template-assisted replication method is demonstrated for the fabrication of hierarchically branched polymeric nanostructures composed of post-modifiable poly(pentafluorophenyl acrylate). Anodic aluminum oxide templates with various shapes of hierarchically branched pores are fabricated by an asymmetric two-step anodization process. The hierarchical polymeric nanostructures are obtained by infiltration of pentafluorophenyl acrylate with a cross-linker and photoinitiator, followed by polymerization and selective removal of the template. Furthermore, the nanostructures containing reactive pentafluorophenyl ester are modified with spiropyran amine via post-polymerization modifi…
Macromol. Chem. Phys. 14/2008
Synthesis and Characterization of Base Labile Poly(N-isopropylacrylamide) Networks Utilizing a Reactive Cross-Linker
Thermo- and light responsive micellation of azobenzene containing block copolymers
In this communication, the synthesis and characterization of thermo- and light responsive block copolymers is reported. PEO-b-PNIPAM polymers with azobenzene moieties were prepared and analyzed by turbidimetry, fluorescence, NMR and DLS measurements. A temperature controlled reversible formation as well as a light induced disruption and reformation of micellar structures in water was found.
Tailoring Properties of Carbon Nanotube Dispersions and Nanocomposites Using Temperature-Responsive Copolymers of Pyrene-Modified Poly(N-cyclopropylacrylamide)
Despite their immense potential, the ability to control the dispersion and microstructure of carbon nanotubes remains a hurdle for their widespread use. Stimuli-responsive polymers show conformational changes with an applied external stimulus (pH, temperature, light, etc.). The dispersion of carbon nanotubes by thermoresponsive polymers is shown to enable the macroscopic properties of aqueous suspensions to be tailored as a function of temperature. This work presents the synthesis, characterization, and use of temperature-responsive poly(N-cyclopropylacrylamide) (PNCPA) polymers containing 1, 3, and 5 mol % pyrene-bearing repeat units to tailor the dispersion state of single-walled carbon n…
From Single Molecules to Nanoscopically Structured Functional Materials
AbstractThe synthesis of MS2 (M = Mo, W) onion-like nanoparticles by means of a high temperature MOCVD process starting from W(CO)6 and elemental sulfur is reported. The reaction can also be carried out in two steps where the intermediate amorphous WS2 nanoparticles formed through the high temperature reaction of tungsten and sulfur in the initial phase of the reaction are isolated and converted in a separate annealing step to onion-type WS2 nanoparticles. Based on a study of the temperature dependence of the reaction a set of conditions could be derived where onion-like structures were formed in a one-step reaction. Onion-like structures obtained in the single-step process were filled, whe…
Reactive Polymers: A Versatile Toolbox for the Immobilization of Functional Molecules on TiO2 Nanoparticles
Topology-Dependent Swichability of Peptide Secondary Structures in Bioconjugates with Complex Architectures
Peptide sequences, which exhibit a reversible pH-responsive coil to α-helix secondary structure transition, are conjugated to polymer precursors to yield linear AB and graft ABA peptide-poly(ethylene oxide) conjugates. While the PEO B-block is comparable, the conjugates differ in topologies of the peptide bearing A-blocks. The influences of topology on the structure transitions in the peptide segments are investigated, comparing linear AB-bioconjugates with graft ABA-bioconjugates having multiple peptide segments combined in star or pom-pom topologies.
Dual Functionalization of Nanostructures of Block Copolymers with Quantum Dots and Organic Fluorophores
Tuning the upper critical solution temperature behavior of poly(methyl methacrylate) in aqueous ethanol by modification of an activated ester comonomer
A statistical copolymer of methyl methacrylate (MMA) and pentafluorophenyl methacrylate (PFPMA, 6 mol%) exhibits upper critical solution temperature (UCST) behavior in aqueous ethanol solutions tunable by post-polymerization modification with different amines. The phase transition behavior of the obtained copolymers in aqueous ethanol was evaluated in detail. As expected, all copolymers reveal an upper critical solution temperature with 55 vol% or higher ethanol content. Furthermore, the solubility in aqueous ethanol of the copolymer can be increased by the introduction of hydrophilic moieties. When hydrophobic substituents are introduced a decrease in solubility was observed with low conte…
Back Cover: Macromol. Rapid Commun. 6/2007
Synthesis of polymeric 1-iminopyridinium ylides as photoreactive polymers
Two synthetic routes to polymeric 1-imino pyridinium ylides as new photoreactive polymeric architectures were investigated. In the first approach, polymerization of newly synthesized 1-imino pyridinium ylide containing monomers yielding their polymeric analogues was achieved by free radical polymerization. Alternatively, reactive precursor polymers were synthesized and converted into the respective 1-imino pyridinium ylide polymers by polymer analogous reactions on reactive precursor polymers. Quantitative conversion of the reactive groups was achieved with pentafluorophenyl ester containing polymers and newly synthesized photoreactive amines as well as by the reaction of poly(4-vinylbenzoy…
Facile synthesis and characterization of functionalized, monocrystalline rutile TiO2 nanorods.
Functionalized, monocrystalline rutile TiO2 nanorods were prepared from TiCl4 in aqueous solution under acidic conditions in the presence of dopamine, followed by aging and hydrothermal treatment at 150 degrees C. The surface-bound organic ligand controls the morphology as well as the crystallinity and the phase selection of TiO2. The presence of monocrystalline rutile TiO2 was confirmed by X-ray powder diffraction and HRTEM investigations. The as-prepared nanorods are soluble in water at pH3. The surface functionalization was analyzed by IR and 1H NMR, confirming the presence of dopamine on the surface. The surface amine groups can be tailored further with functional molecules such as dyes…
Facilitating polymer conjugation via combination of RAFT polymerization and activated ester chemistry
The synthesis of block copolymers via polymer conjugation of well-defined building blocks offers excellent control over the structures obtained, but often several coupling strategies need to be explored to find an efficient one depending on the building blocks. To facilitate the synthesis of polymers with adjustable functional end-groups for polymer conjugation, we report on the combination of activated ester chemistry with RAFT polymerization using a chain transfer agent (CTA) with a pentafluorophenyl ester (PFP-CTA), which allows for flexible functionalization of either the CTA prior to polymerization or the obtained polymer after polymerization. Different polymethacrylates, namely PMMA, …
RAFT Polymerization of Pentafluorophenyl Methacrylate: Preparation of Reactive Linear Diblock Copolymers
Reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) was carried out in the presence of cumyldithiobenzoate and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid, respectively. These chain transfer agents with 2,2'-azoisobutyronitrile (AIBN) as initiator yielded the active ester polymer poly(PFMA) with M n up to 17000 g . mol -1 and low polydispersity index (M w /M n <1.2). Kinetic analysis using 19 F NMR spectroscopy and gel permeation chromatography (GPC) measurements showed controlled polymerization behavior for both chain transfer agents. Successful preparation of linear diblock copolymers consisting of an active ester block and m…
Glossar zu Begriffen mit Bezug zu Kinetik, Thermodynamik und Mechanismen von Polymerisationen
Im Folgenden werden empfohlene Definitionen von grundlegenden Begriffen mit Bezug zu Polymerisationsprozessen vorgestellt. Neuere Entwicklungen im Hinblick auf die Kinetik, die Thermodynamik und die Mechanismen von Polymerisationen machen die Einfuhrung neuer Begriffe und einige Revisionen oder Erweiterungen von Begriffen notwendig, die zuvor im “Compendium of Chemical Terminology” oder im “Glossary of Basic Terms in Polymer Science” definiert wurden.
Functionalization of Porous Polymers from High‐Internal‐Phase Emulsions and Their Applications
Synthesis of Defined Poly(silsesquioxane)s: Fast Polycondensation of Trialkoxysilanes in a Continuous-Flow Microreactor
The polycondensation of trialkoxysilanes to PSSQs in a microreactor setup is demonstrated. While continuous-flow processes involving microreactors found various applications in chain growth polymerization, their influence on step-growth polymerization is less explored, and the polycondensation of multifunctional monomers has not been studied in detail. We found significantly increased yields and a decreased polydispersity of the obtained polymers in comparison to the batch process. By variation of the residence time molecular weights could be adjusted reproducibly ranging from M n =1900 to 11000 g · mol -1 . Thus, the microreactor setup offers for the first time the possibility to synthesiz…