Microgel reactive groups

Reactive microgels are crosslinked polymer particles which have a diameter of some 100 A and contain pendant reactive groups like vinyl groups. Such microgels may be copolymerized with bifunctional monomers to obtain crosslinked polymers in which the microgel particles act as multifunctional cross-linking sites (J ). In some respects such crosslinked polymers are comparable with other multiphase polymer systems like block or graft polymers. 

In addition to the above-mentioned, rather painstaking, techniques of polypeptide syntheses, a very elegant technique was developed by Merrifield. This solid-phase peptide synthesis automates the reaction sequences. The method makes use of an insoluble crosslinked polymer substrate with pendant reactive groups for attachment of peptide chains. Chloromethylated polystyrene microgels are often used (see Chapter 8 for more discussions on the use of chloromethylated polystyrene for reactions of polymers). The chloromethyl moieties serve as the initiating sites for formation of the polypeptides ... 

The reactivity of microgels resides in terminal carboxyl acid groups and in residual unsaturated dicarboxylic acid groups of the EUP-component. Due to sterical hindrance, presence of less reactive maleic acid units and deactivation of termi-... 

Almost linear polymers with pendant vinyl groups are formed as intermediates in the anionic polymerization of 1,4-DVB due to the different reactivities of monomers and pendant vinyl groups. 1,4-DVB microgels are formed towards the end of monomer conversion. In the anionic polymerization of EGDM or 1,3-DVB, reactive microgels are formed already at the beginning of the polymerization. 

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