CONTROLLED COPOLYMER STRUCTURES VIA ANIONIC INSERTION POLYMERIZATION OF CYCLIC CARBONATES

Cyclic carbonates are polymerized in a ring-opening fashion by means of anionic and insertion type initiators. Different hexacyclic carbonates are copolymerized in a random way when both monomers are added to the initiator simultaneously. Block copolymers are obtained when the monomers are added in sequential way. With anionic initiators cyclic carbonates are polymerized preferentially as compared with lactones while insertion initiators are less selective. A special case is the preparation of copolymers of carbonates with lactams. When the polycarbonate is formed first the lactam unit is inserted into carbonate bond to form urethane and ester bonds. Thus, eventually an alternating polyesterurethane is formed with negligible amount of carbonate, amide, and urea units. Moreover, the anionic ring-opening polymerization of cyclic carbonates may be combined with vinyl polymerization. In the case of group transfer polymerization a transformation of the active site to the non-metallic anionic initiation of the cyclic carbonate occurs.