Microspheres by dispersion polymerization of lactides and ϵ‐caprolactone

Abstract

Polyester 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.

Synthesis of poly(ε-caprolactone)–silica nanocomposites: from hairy colloids to core–shell nanoparticles

“…To our knowledge, dispersion polymerization is the only way to obtain PCL latex particles by in situ heterophase polymerization. Dispersion polymerization of e-caprolactone has been extensively studied by Slomkowski et al 34,40,41 in a 4 : 1 (v/v) mixture of heptane and 1,4-dioxane using a graft copolymer, poly(dodecyl acrylate)-g-poly(e-caprolactone), as steric stabilizer. According to this author, polymerization is initiated in solution until the formation of stable primary particles.…”

Electrical coupling, receptive fields, and relative rod/cone inputs of horizontal cells in the tiger salamander retina

“…In this publication, we report the design and synthesis of a series of novel diblock copolymer stabilizers based on PCL, a polymer‐philic material found to be successful in previous stabilizer design,43, 45–47 and Krytox 157FSL, a commercially available carboxylic acid terminated perfluoropolyether (PFPE). This particular PFPE has been used previously as a stabilizer for free‐radical polymerization,48, 49 and the carboxylic acid head group has been shown to be sufficiently reactive to allow modification by conventional wet chemistry techniques 9, 50.…”

Novel Macromolecular Architectures Based on Aliphatic Polyesters: Relevance of the “Coordination-Insertion” Ring-Opening Polymerization

“…For instance, Slomkowski et al have prepared microspheres by the straightforward dispersion polymerization of L-LA and εCL in a solvent mixture in which the generated polyesters are poorly soluble. The polymerizations were carried out in a 1,4-diox-ane/heptane solvent mixture and were promoted by either Sn(C 1 Ct) 2 catalyst or aluminum alkoxide initiators [115]. The dispersion of the growing polyester particles was actually stabilized by poly(dodecylacrylate-g-caprolactone) graft copolymers.…”