Copolymers of the ST and the IPCA monomers were prepared (Scheme 2) in 25-mL glass screw cap vials at ST/IPCA = 3 (mol) the monomer feed using 0.12 mol/L of ABCN at an overall monomer concentration 2.44 mol/L in 10 mL of toluene. The copolymerization was conducted at 70ºC. After a predetermined time, the mixture was cooled to room temperature, and precipitated dropwise in methanol. The conversion of the copolymers was kept between 10 and 20% to minimize compositional drift (Table ). The composition of the copolymers was determined based on the nitrogen content. Since IPCA monomers do not homopolymerize, the most likely structure of the copolymers would be isolated IPCA monomer units alternating with short ST sequences (Scheme 2). Copolymerization of ST and the phenoxy ring-substituted IPCA resulted in formation of copolymers (Table ) with weight-average molecular masses 17 to 35 kD. According to the nitrogen elemental analysis, between 25.9 and 33.4 mol% of TSE monomer is present in the copolymers prepared at ST/IPCA = 3 (mol), which is indicative of relatively high reactivity of the monomers towards ST. a Polymerization time was 5 h