RING-OPENING POLYMERIZATION AND COPOLYMERIZATION OF CYCLIC CARBONATESWITH A VARIETY OF INITIATING SYSTEMS

The ring-opening polymerization of cyclic monomers is a field of long tradition. More recently, however, under the pressure to recycle polym ers the generally undesired capability of ring-closing depolymerizatio n has gained a new aspect. As an example, the anionic ring-opening pol ymerization of six-membered cyclic carbonates is discussed, the alcoho late being the active species. The latter is also able to initiate the ring-opening polymerization of lactones such as epsilon-caprolactone and pivalolactone. On the other hand, monofunctional and bifunctional alcoholates of polytetrahydrofuran can be used as initiators for the a nionic ring-opening polymerization of cyclic carbonates to produce AB- and ABA-block copolymers. The use of other initiators than alcoholate s on the basis of Al, Zn, and Sn is discussed for both the polymerizat ion and the depolymerization reaction.