Search results for "Macro"
showing 10 items of 3471 documents
Synthesis strategies and properties of smart amphiphilic networks
1996
This paper briefly surveys recent developments in the field of amphiphilic networks (APN) which are a new class of crosslinked polymer systems consisting of covalently bonded hydrophobic and hydrophilic chain segments. The covalent bonds between immiscible hydrophobic and hydrophilic polymer chains prevent demixing and yield polymer networks with unique structure and properties. Telechelic macromonomers provide the basis for the first generation of APNs obtained by copolymerization of the macromonomer with selected low molecular weight monomers. Synthesis of a variety of APNs using methacrylate-telechelic polyisobutylene (PIB) macromonomers prepared by living carbocationic polymerization (L…
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 …
Amphiphilic poly(ether urethanes) carrying associative terpyridine side groups with controlled spacing
2021
The rational design of transiently crosslinked polymer gels requires a profound understanding of how molecular and topological factors determine the mechanical and dynamic material properties. To refine so-far established structure–property relations, complementary and versatile model sytems are still a crucial prerequisiste. In this study, the synthesis of a metallo-supramolecular associating terpyridine-diol (referred to as sticker) and its incorporation into poly(ethylene glycol) (pEG) based polyurethanes (PU) with strictly alternating vs. random sequences and variable sticker spacings is described. Synergetic effects resulting from the proximity of multiple neighboring urethane and stic…
Some photochemical transformations of polymers
1969
Abstract Several light-induced reactions of polymers are described. The light-sensitive groups are part of the macromolecules. Photoisomerization of polyvinylbutyral produces a polymer with vinylbutyrate-groups. At exposure to light, furan and benzofuran are added to the carbonyl-groups of polyvinylbenzophenone. Polymers with azido-groups are prepared, which eliminate nitrogen at irradiation. Light-sensitive films can be cast from polymers with o-quinonediazide-groups.
Synthetic approaches to new polymers
1990
A plenary lecture should be an introduction into the main topic of the symposium and a review about the state of art. Therefore, in the first part of this presentation different possibilities for the preparation of new polymers are briefly discussed from a chemical point of view. Some selected examples from the literature show how methods of organic chemistry can be utilized for polymer science: new catalytic systems, new monomers, modification of polymers, new poly-reactions. In the second part, several polyelectrolytes are described: polymers with sec., tert. and quart. N-atoms in the main chain, block copolymers and block polyampholytes. The third part deals with the problems of rod-like…
Interpolymer complexes and polymer compatibility.
2012
A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [η] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, …
Synthesis of polyvinyl acetate-graft-poly-2-oxazolines
1994
Poly(vinyl acetate-co-vinyl chloroformate) (1) was synthesized via phosgenation of poly(vinyl acetate-co-vinyl alcohol). It was shown that (1) is capable of initiating the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline, when the counter ion is exchanged using potassium iodide. Polyvinyl acetate-graft-poly-2-phenyl-2-oxazoline and polyvinyl acetate-graft-poly-2-methyl-2-oxazoline are obtained in the grafting reaction.
Synthesis and large scale fractionation of non-linear polymers: brushes and hyperbranched polymers
2002
Polymer brushes with poly(methyl methacrylate) (PMMA) backbone and polystyrene side chains were synthesized by radical polymerization of ω-methacryloyl-polystyrene macromonomers. Hyperbranched PMMA was obtained by means of self-condensing group transfer copolymerization of methyl methacrylate with an initiator-monomer containing a polymerizable methacryloyl moiety and an initiating silylketeneacetal function. Both non-linear products were fractionated using the method of continuous polymer fractionation, consisting in a particular type of continuous countercurrent extraction. The combination of methyl ethyl ketone (solvent) with acetone (AC) (precipitant) turned out to be suitable for the f…