Styrene/4-vinylbenzoic acid copolymer

For example, the single-stage preparation of the polymers and copolymers of styrene with LM of the 9-anthrylmethyloxycarbonyl structure (Table 1 LMi) by copolymerization is accompanied by homolytic side reactions (Scheme 1). However, such labeled polymers can be obtained in two stages by copolymerization of the main monomer with the labeling amount of acrylic, methacrylic or vinylbenzoic acids and subsequent anthrylmethylation of the carboxylic groups of the polymer using 9-anthryldiazomethane. 

Mahadevan employs an insoluble copolymer of styrene (88%) -vinylbenzoic acid (12%) and -divinylbenzene (0.2% or 0.02 %>). The carboxyl groups on the polymer were converted into acid chlorides with thionyl chloride and allowed to react with 5 -O-trityl-2 -deoxycytidine (VIII) to yield IX. Condensation of IX with cyanoethylphosphate and mesitylenesulfonyl chlorixfe or DCC gave X. When X was activated with mesitylenesulfonyl chloride and... 

More recently controlled free radical polymerization methodologies have been employed for the preparation of novel smart AB diblock copolsrmers. Nitroxide-mediated polymerization was utilized for the synthesis of sodiiun 4-styrenesulfonate-block-sodium 4-vinylbenzoate block copolymer (133). These strong acid/weak acid species exhibit reversible pH-induced self-assembly, with the sodium 4-styrenesulfonate residues remaining ionized and thns permanently hydrophilic over the useful pH range whereas the sodium 4-vinylbenzoate block can be reversible protonated (the carboxylate residue has a pa s 4.0). The same block polymers can also be prepared via RAFT, albeit with somewhat more control. Other workers reported the preparation of such AB diblock copolymers as well as some analogous amine-based styrenic diblock copolymers, (48) shown in Figure 54. 

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