COPOLYMERS WITH SOFT AND HARD SEGMENTS BASED ON 2,2-DIMETHYLTRIMETHYLENE CARBONATE AND EPSILON-CAPROLACTONE

Thermoplastic elastomers with ABA-block structure, A representing the hard segment and B the soft segment, were prepared by ring-opening pol ymerization from 2,2-dimethyltrimethylene carbonate (DTC, 1) and epsil on-caprolactone (ECL, 2) as monomers. Typical anionic initiators, viz. the dilithium salt of hydroxytelechelic poly(ethylene oxide) 200 (4) and of polytetrahydrofuran 1 000 (5) and as an insertion initiator the bis(diethylaluminium) salt of triethylene glycol were used. The soft block is formed by a sequence of random (or tapered) structure compris ing equimolar amounts of the two monomers and obtained by simultaneous polymerization of DTC and ECL. The hard blocks consist of highly crys talline poly(2,2-dimethyltrimethylene carbonate) sequences. The therma l properties of the polymers depend on the sequence length, the conten t of heterodiads in the soft block and the thermal history of the samp les. Copolymer films with short end blocks and high content of heterod iads show rubber-elastic properties at normal conditions.