Search results for "polymerization"
showing 10 items of 1689 documents
Oligoethyleneoxide spacer groups in polymerizable surfactants
1991
Cationic and zwitterionic polymerizable surfactants bearing tri- and tetraethyleneglycol spacer groups between the polymerizable moiety and the surfactant structure were prepared and polymerized. Monomers and polymers were investigated with respect to their aggregation behavior in aqueous systems and compared to analogous monomers and polymers lacking spacer groups. In the case of the monomeric surfactants, the spacer groups depress both the Kraffttemperature and the critical micelle concentration. the area occupied per molecule at the air-water interface is substantially enlarged by the spacers, whereas the depression of surface tension is nearly constant. Although the monomers with and wi…
Poly-l-Lysine-Poly[HPMA] Block Copolymers Obtained by RAFT Polymerization as Polyplex-Transfection Reagents with Minimal Toxicity
2015
Herein we describe the synthesis of poly-L-lysine-b-poly[N-(2-hydroxypropyl)-metha-crylamide)] (poly[HPMA]) block copolymers by combination of solid phase peptide synthesis or polymerization of α-amino acid-N-carboxy-anhydrides (NCA-polymerization) with the reversible addition-fragmentation chain transfer polymerization (RAFT). In the presence of p-DNA, these polymers form polyplex micelles with a size of 100-200 nm in diameter (monitored by SDS-PAGE and FCS). Primary in vitro studies with HEK-293T cells reveal their cellular uptake (FACS studies and CLSM) and proof successful transfection with efficiencies depending on the length of polylysine. Moreover, these polyplexes display minimal to…
Synthesis and radical polymerization of novel methacrylates with mesoionic 6-oxo-1,6-dihydropyrimidin-3-ium-4-olates as photosensitive components
2001
New polymerizable mesoionic 6-oxo-1,6-dihydropyrimidin-3-ium-4-olates 5a-f have been synthesized using tosylated 2-hydroxymethyl methacrylate and various thioureas and malonic acids. Radical polymerization of the mesoionic derivatives 5a, c, d, e with AIBN as initiator resulted in soluble polymers, which were used for the preparation of photosensitive films.
Nonionic Maleic Surfmers
2002
ABSTRACT A set of nonionic maleic surfactants have been prepared, all coming from the derivatization of maleic hemiesters with a long alkyl chain. They are either amidoesters or diester products. In the case of amidoesters, the acid group was first activated and then reacted with primary or secondary or tertiary ethanolamine compounds. In the case of diesters, the hemiester was reacted directly with glycidol, in acid or basic conditions. These surfactants were characterized for their structure by 1H NMR, and for their surface active properties, by surface tension measurements. They were also used in batch emulsion polymerisation of styrene, and seeded core-shell copolymerisation of a 1/1 mi…
Mesogen-Initiated Linear Polyglycerol Isomers: The Ordering Effect of a Single Cholesterol Unit on “Sticky” Isotropic Chains
2011
Synthesis, thermal properties, and the liquid crystalline (LC) order of polymers consisting of a single mesogenic cholesterol unit and flexible, linear polyglycerol (PG) or poly(glyceryl glycerol) (PGG) chains have been investigated. Incorporation of the single mesogen has been achieved by using cholesterol directly as an initiator for the oxyanionic ring-opening polymerization (ROP) of ethoxyethyl glycidyl ether (EEGE) or isopropylidene glyceryl glycidyl ether (IGG). The controlled polymerization allowed the synthesis of a series of peculiar rod–coil type polyethers with molecular weights of 600–2300 g/mol, representing a degree of polymerization (DPn) of 4–30 for both PG and PGG with the …
Poly(2-oxazoline)s Functionalized with Palladium Carbene Complexes: Soluble, Amphiphilic Polymer Supports for C−C Coupling Reactions in Water
2004
This paper describes the synthesis and characterization of a new class of amphiphilic, water-soluble diblock copolymers based on 2-oxazoline derivatives with pendent N-heterocyclic carbene/palladium catalysts in the hydrophobic block. The synthetic strategy involves a four-step synthesis of three functionalized monomers, each composed of a bis(imidazoline-2-ylidene)palladium(II) diiodide derivative that is covalently linked to a 2-oxazoline monomer via a flexible alkyl spacer (alkyl = butyl, hexyl, octyl). The structure of the monomers was analyzed by 1H and 13C NMR spectroscopy, MALDI-TOF, and elemental analysis. Three diblock copolymers P1−P3 with the monomers being part of the hydrophobi…
Non-linear effect of 18-crown-6 in propylene oxide polymerization with potassium glycidoxide used as the inimer
2004
A new initiating system containing potassium glycidoxide as the inimer and 18-crown-6 as the activator was used for propylene oxide polymerization. It was found that the rate of the reaction increased together with the crown ether concentration in a rather unexpected way. Two maxima of that parameter were found in the case of crown ether : inimer molar ratio equal to 3:1 and 6:1. On the other hand, the molecular weight of polymers showed two minima in those conditions. The heterogeneity of the reaction mixture and interactions between species present in the system could be responsible for the phenomena observed. The polydispersity of the polymers obtained was equal to about 1.2 and it was i…
Combining Orthogonal Reactive Groups in Block Copolymers for Functional Nanoparticle Synthesis in a Single Step.
2017
We report on the synthesis of polysarcosine-block-poly(S-alkylsulfonyl)-l-cysteine block copolymers, which combine three orthogonal addressable groups enabling site-specific conversion of all reactive entities in a single step. The polymers are readily obtained by ring-opening polymerization (ROP) of corresponding α-amino acid N-carboxyanhydrides (NCAs) combining azide and amine chain ends, with a thiol-reactive S-alkylsulfonyl cysteine. Functional group interconversion of chain ends using strain-promoted azide–alkyne cycloaddition (SPAAC) and activated ester chemistry with NHS- and DBCO-containing fluorescent dyes could be readily performed without affecting the cross-linking reaction betw…
Orthogonally reactive amino acids and end groups in NCA polymerization
2017
Functional amino acids whose reactivity is compatible with the polymerization of α-amino acid-N-carboxyanhydrides (NCAs) have received a lot of attention in recent years. The appeal of these reactive monomers lies in the fact that the resulting polymers can be easily modified in one controlled post-polymerization step, leading to a variety of polypeptidic materials like helical non-natural polycations or glycopeptides. This review highlights recent developments in the field and focuses on the different reactive groups like alkynes, alkenes, azides, chlorides and S-alkylsulfonyls. Furthermore, the modifications after polymerization are discussed, pointing out advantages and challenges. Besid…
Saccharide modified silica particles by enzymatic grafting
1997
The surface of silica particles has been chemically modified with oligo- or poly-(α,1→4)-D-glucopyranose (amylose) chains of various length by covalently attaching maltoheptaose derivatives to the solid support and enzymatic polymerization of glucose-1-phosphate with a potato phosphorylase as catalyst. The characterization of the products by solid-state NMR spectroscopy showed an interesting dependence of the linewidth with the grafting density of the glucan chains. The modified silica particles showed chiral discrimination in liquid chromatography.