Microspheres by dispersion polymerization of lactides and ϵ‐caprolactone

Abstract

AbstractPolyester microspheres were synthesized by the ring‐opening polymerization of lactides (racemate or optically active L,L‐isomer) and ϵ‐caprolactone. Polymerizations were carried out in the 1,4‐dioxane‐heptane mixed solvents in the presence of poly(dodecyl acrylate)‐g‐poly(ϵ‐caprolactone) (poly(DA‐CL)) used as surface‐active agent. Polymerizations were initiated with tin(II) 2‐ethylhexanoate (lactides), diethylaluminum ethoxide or sodium trimethylsilanolate (ϵ‐caprolactone). In the studies of the polymerization of lactides, relations were determined between diameters, the distribution of diameters of synthesized microspheres, and the structure of poly(DA‐CL). It was found that it is possible, depending on thermal treatment of microspheres after synthesis, to obtain polylactide microspheres differing in the degree of crystallinity. Kinetics of the dispersion pseudoanionic and anionic polymerizations of ϵ‐caprolactone were also investigated and the results of these studies were compared with the data for the corresponding polymerizations of ϵ‐caprolactone in solution.