Random and block copolymerizations of L- or D-lactide with epsilon-caprolactone (CL) were performed with a novel anionic initiator, (C5Me5)(2)SmMe(THF), and they resulted in partial epimerization, generating D,L- or meso-lactide polymers with enhanced biodegradability. A blend of PLLA-r-PCL [82/18; PLLA = poly(L-LA) and PCL = poly(epsilon-caprolactone)] and PDLA-r-PCL [79/21; PDLA = poly(D-LA)] prepared by the solution-casting method generated a stereocomplex, the melting temperature of which was about 40degreesC higher than that of the nonblended copolymers. A blend of PLLA-b-PCL (85/15) and PDLA-b-PCL (82/18) showed a lower elongation at break and a remarkably higher tensile modulus than stereocomplexes of PLLA-r-PCL/PDLA-r-PCL and PLLA/PDLA. The biodegradability of a blend of PLLA-r-PCL (65/35) and PDLA-r-PCL (66/34) with proteinase K was higher than that of PLLA-b-PCL (47/53) and PDLA-b-PCL (45/55), the degradability of which was higher than that of a PLLA/PDLA blend. A blend film of PLLA-r-PDLLA (69/31)/PDLA-r-PDLLA (68/32) exhibited higher degradability than a film of PLLA/PDLLA [PDLLA = poly(D,L-LA)]. A stereocomplex of PLLA-r-PCL-r-PDMO [80/18/2; PDMO = poly(L-3,D,L-6-dimethyl-2,5-morpholinedion)] with PDLA-r-PCL-r-PDMO (81/17/2) showed higher degradability than PLLA-r-PDMO (98/2)/PDLA-r-PDMO (98/2) and PLLAr-PCL (82/18)/PDLA-r-PCL (79/21) blends. The tensile modulus of a blend of PLLA-r-PCLr-PDMO and PDLA-r-PCL-r-PDMO was much higher than that of a blend of PLLA-rPDMO and PDLA-r-PDMO. (C) 2004 Wiley Periodicals, Inc.