CONTROLLED COPOLYMER STRUCTURES VIA ANIONIC INSERTION POLYMERIZATION OF CYCLIC CARBONATES

Cyclic carbonates are polymerized in a ring-opening fashion by means o f anionic and insertion type initiators. Different hexacyclic carbonat es are copolymerized in a random way when both monomers are added to t he initiator simultaneously. Block copolymers are obtained when the mo nomers are added in sequential way. With anionic initiators cyclic car bonates are polymerized preferentially as compared with lactones while insertion initiators are less selective. A special case is the prepar ation of copolymers of carbonates with lactams. When the polycarbonate is formed first the lactam unit is inserted into carbonate bond to fo rm urethane and ester bonds. Thus, eventually an alternating polyester urethane is formed with negligible amount of carbonate, amide, and ure a units. Moreover, the anionic ring-opening polymerization of cyclic c arbonates may be combined with vinyl polymerization. In the case of gr oup transfer polymerization a transformation of the active site to the non-metallic anionic initiation of the cyclic carbonate occurs.