Graft copolymers initiation methods

A number of methods have been used to prepare graft copolymers in the past few decades including both conventional chemical and radiation-chemical methods [20,86,87]. In the latter case, graft copolymerization is usually initiated by creating active radical sites on existing polymer chains. The advantages of radiation-chemical methods are (i) ease of preparation as compared to... 

ATRP and grafting from methods led to the synthesis of poly(styrene-g-tert-butyl acrylate)-fr-poly(ethylene-co-butylene)-fr-poly(styrene-g-ferf-butyl acrylate) block-graft copolymer [203]. ATRP initiating sites were produced along the PS blocks by chloromethylation as shown in Scheme 112. These sites then served to polymerize the ferf-butyl acrylate. The poly(ferf-butyl acrylate) grafts were hydrolyzed to result in the corresponding poly(acrylic... 

In this article, the use of anionic and cationic surface-initiated methods to form homopolymer and block copolymer brushes grafted from flat and nanoparticle surfaces has been reviewed. The future challenge in understand-... 

Mino, G., and S. Kaizerman A new method for the preparation of graft copolymers. Polymerization initiated by ceric ion redox systems. J. Polymer Sci. 31, 242 (1958). 

Graft Copolymers via Polymeric Azo Initiators 3.1 Grafting Methods... 

The irradiation of a mixture of two polymers A and Bn, either in the solid state or in solution, yields free radicals A and Z , which by recombination give the initial An and Bn polymers or by cross-addition a graft (or block) copolymer 4j,BQ. Although this method gives only very low yields of graft copolymers, it has nevertheless be applied by Hekg-lein in the system polyvinylpyrrolidone-polyacrylamide (102). 

Ionic polymerisation is a well-known technique for the preparation of graft copolymers but the fate of these reactions is determined by the reaction conditions. Since the discovery of living polymerisation , (anionic polymerisation) [67] it has become an excellent method for the synthesis of block and graft copolymers. In anionic polymerisation the graft copolymerisation is initiated by the anion generated by the reaction of bases with acidic protons in the polymer chain as shown in Scheme 2. 

Usually the Zigler-Natta co-ordination initiator system is used to graft oc-olefins onto other polymers to give stereo block/graft copolymers, which contain isotactic/atactic sequences. In the Zigler-Natta co-ordination catalyst [69] system, the diethyl aluminium hydride reacts with pendant groups to form macromolecular trialkyl aluminium. The residual initiator is freed by extraction methods. 

Furthermore, by using the ATRP method with a tetrafunctional initiator, the star copolymers consisting of four PMMA-g-EPR graft copolymer arms were also synthesized (Fig. 22). These unique topologies of the obtained copolymers can be confirmed by GPC measurement and NMR analysis. From TEM observation, the morphologies of these graft and star copolymers were remarkably altered by changing EPR branch number and the structure of the... 

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