Benzene → Isoprene

Participants

Reaction Steps

Styrene-isoprene block copolymers were synthesized by a two-stage process. In the first stage, living poly(styrene) was synthesized to initiation with sec-butyl lithium in benzene at an initiator level calculated to yield a 50,000, Mn, "living" polystyryl anion. The polymerization was carried out at 0° C. for 30 minutes after which time the reaction mixture was held at ambient temperature for 1 hour. The solution of living polymer was then split and isoprene was added to each fraction. In the first instance, an amount of isoprene sufficient to yield an isoprene block segment Mn, about 70,000, was added; in the second a larger amount of isoprene sufficient to yield an isoprene block segment of 100,000 Mn was added. In each instance the polymerization was carried out for about 2 hours at 0° C. followed by 19 hours at ambient temperature.

Provenance & Evidence