Copolymerization (Sch. 1) of VAC and the halogen ring-substituted HECP resulted in formation of copolymers (Table ) with weight-average molecular masses 5.2 to 9.2 kD. According to the nitrogen elemental analysis, between 45.2 and 49.4 mol% of TSE monomer is present in the copolymers prepared at VAC/HECP = 3 (mol), which is indicative of relatively high reactivity of the monomers towards VAC.