Search results for "Radical"
showing 10 items of 1401 documents
Block Copolymers Build-up of Electron and Hole Transport Materials
2004
In this article we describe the synthesis of various monomers modified with triphenyl-1,3,5-triazine side groups as electron transport moieties. By nitroxide-mediated polymerization with a TEMPO unimer it was possible to obtain polymers with a narrow polydispersity. Furthermore, by living radical polymerization block copolymers were obtained from these monomers. Therefore, microphase separated structures are accessible which possess hole conducting moieties in one phase and electron conducting moieties in the other phase.
Functional Diblock Copolymers for the Integration of Triboluminescent Materials into Polymer Matrices
2008
This work describes the synthesis and use of new diblock copolymers to integrate functional inorganic particles into a polymer matrix. These diblock copolymers were synthesized by nitroxide-mediated polymerization (NMP) from styrene and two styrene-like monomers with protected functional groups for the later connection to the functional inorganic material. It was possible to keep the polydispersity of the block copolymers around or below 1.2 and to preset the length of the functional block to about 20 monomers or 10 mol-% of monomers. The groups for the surface functionalization (amino groups or chelating ligands) were obtained in their free form by polymer analogous reactions. As an exampl…
Liquid Crystals from Polymer-Functionalized TiO2 Nanorod Mesogens
2008
In this work, we functionalized TiO2 nanorods with dopamine-functionalized diblock copolymers. After functionalization, they are well dispersible in organic solvents. Light scattering proves that t...
Novel Amphiphilic Styrene-Based Block Copolymers for Induced Surface Reconstruction
2008
This paper describes the synthesis of amphiphilic block copolymers by living radical polymerization (NMP) of new styrene-like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl- or amino-groups after deprotection) were polymerized in a “protected form” to adjust the solubility of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. In the bulk state hydrophobic and hydrophilic domains demix. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83°…
Copolymerization of methacryloyl-terminated PMMA macromonomers with methyl methacrylate
1992
Methacryloyl-terminated macromonomers (MM) of polymethylmethacrylate (PMMA) of two different molecular weights were prepared by group transfer polymerization (GTP). They were copolymerized with methyl methacrylate (MMA) by radical polymerization using toluene as the solvent. The relative reactivity of the MM, 1/r1, decreases with increasing initial MM concentration. This is interpreted as a consequence of the increasing viscosity of the reaction medium leading to an increasing diffusion control of the MM addition. At a constant weight ratio of MMA to MM the reactivity of the longer macromonomer is higher than of the shorter one. Increasing the molar ratio [MMA]/[MM], i.e. increasing the ave…
Synthesis of well-defined polymeric activated esters
2008
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…
Synthesis of Functional Inorganic−Organic Hybrid Polymers Based on Poly(silsesquioxanes) and Their Thin Film Properties
2008
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 …
Oligo(glycerol) Methacrylate Macromonomers
2011
Linear, protected ω-methoxy oligo(glycerol) methacrylate (OGly(P)MA) macromonomers are synthesized via anionic ring-opening polymerization of ethoxyethyl glycidyl ether (EEGE) followed by termination with methacrylic acid anhydride (DP(n) = 3-11, PDI < 1.30). The covalently bound methacrylate moiety allows the homopolymerization of OGly(P)MA as well as copolymerization with low molecular weight comonomers. In homopolymerizations, macromonomers are polymerized by atom transfer radical polymerization (ATRP) yielding well-defined graft polymers (M(n) = 20,000-30,000 g mol(-1)). Acidic hydrolysis of the protecting groups releases water-soluble polyhydroxy-functional structures. First results on…
Highly cross-linked imidazolium salt entrapped magnetic particles – preparation and applications
2012
Magnetic particles entrapped into highly cross-linked imidazolium salts were synthesized using a straightforward approach by radical polymerization of bis-vinylimidazolium salts in the presence of superparamagnetic iron oxide particles. Potential applications for these new materials as (i) catalysts for conversion of propylene oxide to propylene carbonate, (ii) supports for organocatalysts, and (iii) scavenger materials for palladium removal are outlined.
Redox active polymers with phenothiazine moieties for nanoscale patterning via conductive scanning force microscopy
2011
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…