BLOCK AND RANDOM COPOLYMERS OF EPSILON-CAPROLACTONE

Conditions of the living homopolymerization of epsilon-caprolactone (C L), lactides (LA), and of the homo-oligomerization of gamma-butyrolact one (BL) are briefly described. Then block and random copolymerization s of CL with LA are shortly reviewed. The microstructure of the result ing copolyesters in relation to some peculiarities of these processes is discussed in more detail. It is also shown that the otherwise 'non- polymerizable' BL does form high molecular weight copolymers with CL, containing up to 50 mol% repeating units derived from BL. Their molecu lar weight is controlled by the concentrations of the consumed comonom ers and the starting concentration of the initiator. NMR and DSC data indicate the random structure of copolymers. TGA traces of the BL/CL c opolymers show that the presence of the gamma-oxybutyryl repeating uni ts randomly distributed within the poly(CL) chains improves the therma l stability of the latter. (C) 1998 Elsevier Science Limited. All righ ts reserved.