Telechelics 6. Oligostyrenes by radical polymerization

Styrene polymerized by AIBN as initiator results in telechelic α,ω‐bis(1‐cyano‐1‐methylethyl)oligostyrenes ( 1 ). The functionality, f CN , was found to be 1,99 ± 0,05 in the molecular weight range up to 2000 and the M w / M n ‐values were found to be < 1,5 after complete consumption of the initiator. Using methyl 2,2′‐azoisobutyrate as initiator, oligostyrenes with two ester endgroups were obtained. The conversion of styrene was limited by “dead end” conditions as described by Tobolsky. The efficiency was 0,9 under the preparative conditions used. The cyano endgroups were converted into amino endgroups by hydrogenation and into carboxyl endgroups by hydrolysis. Telechelic α,ω‐bis(2‐isocyanato‐1,1‐dimethylethyl)‐ and α,ω‐bis(1‐isocyanato‐1‐methylethyl)oligostyrenes 4 and 6 were obtained from the amino product 2 by the phosgene method and from the carboxyl product 3 by the Weinstock/Curtius reaction, respectively. Connecting these telechelic styrene blocks by a polyreaction results in polymers in the 20 000 – 50 000 molecular weight range.