Cyclic ketones, copolymerization with

The above examples of free-radical ring-opening polymerization, which have been explored by Bailey and Endo, produce polymers containing ketonic carbonyl and/or ester groups in the main chain. In addition, these cyclic monomers can be copolymerized with vinyl monomers by free-radical mechanism. Thus, the variety of the polymers produced by radical polymerization has been enlarged. 

The radical copolymerization of cyclic ketene acetal with various vinyl monomers such as styrene, MMA, vinyl acetate, and methyl vinyl ketone could afford the copolymers with ester groups in the main chain (26-28). These copolymers showed enzymatic degradability and photodegradability and are applicable as environmentally degradable materials. 

The cyclic structure of the polymers [31] was substantiated by infrared and chemical evidence. The fact that they were soluble (acetone, methyl ethyl ketone, acetic acid, dioxane) confirms their linear character. The polymerizations were also initiated by other radical initiators [peroxides, azobis(iso-butyronitrile)]. Carbinols with aliphatic, cycloaliphatic, and aromatic substituents were polymerized (104,106,109, 111, 113,119-121). Cyclic polymers are also obtained from their acetates and ethers (107, 113). Nuclear magnetic resonance has been employed to study transitions in these polymers (75, 76). Polymers possessing molecular weights of over 1,000,000 resulted in some cases. The kinetics of polymerization (11-14) were studied (111, 112). Copolymerization with vinyl monomers (108, 145) yielded linear, soluble polymers that contained cyclic structures derived from the vinylethynyl carbinol. 

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