COPOLYMERS WITH PERIODIC COMONOMER SEQUENCES

The free radical copolymerization and multipolymerization of olefins with acrylic monomers in the presence of acids has been studied. It was found that Bronsted acids are as suitable complexing agents for the acrylic comonomer as the up to now exclusively used Lewis acids. The effectiveness of the Bronsted acids, e.g. carboxylic acids, for obtaining alternating copolymers increased with the pKs value, and trifluoroacetic acid turned out to be the acid of choice. The variation of the Lewis acid-type complexation agents was extended by the zinc chloride diethylether complex which is advantageous over ZnCl2 or other Lewis acids because of its good solubility and recycling practicability, which is also a feature of the Bronsted acids. The versatility of the new complexing agent systems was demonstrated in a series of co- and multipolymerizations, and ethyl cyanoacrylate was employed for the first time as electron acceptor comonomer. The properties of the copolymers with periodic comonomer sequences varied systematically with their composition, e.g. the glass transition temperature and the degree of crystallinity.