Block copolymers from iniferters

The polymeric disulfide iniferter consisting of poly(DMS) 33 was also similarly prepared (Eq. 31) [ 143,151 ]. Block copolymers of poly(DMS) with MMA or St were synthesized with from two to eight blocks of both sequences per chain. 

The synthesis of some multiblock copolymers was attempted by successive polymerization using this iniferter technique. However, pure tri- or tetrablock copolymers free from homopolymers were not isolated by solvent extraction because no suitable solvent was found for the separation. In 1963, Merrifield reported a brilliant solid-phase peptide synthesis using a reagent attached to the polymer support. If a similar idea can be applied to the iniferter technique, pure block copolymer could be synthesized by radical polymerization. The DC group attached to a polystyrene gel (PSG) through a hydrolyzable ester spacer was prepared and used as a PSG photoiniferter (Eq. 53) [186] ... 

As stated previously, the iniferter method is not suitable for aU monomers. Therefore, the application of a single mode polymerization technique for the synthesis of block copolymers is severely limited, and suffers from the requirement for care in the order of monomer addition. In order to extend the range of monomers for the synthesis of block copolymers, a mechanistic transformation approach was proposed, by which the polymerization... 

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