Polymerization of (L,L)‐lactide and copolymerization with ϵ‐caprolactone initiated by dibutyltin dimethoxide in supercritical carbon dioxide

Abstract

Ring-opening polymerization (ROP) of (L,L)-lactide (LA) has been initiated by dibutyltin dimethoxide in supercritical carbon dioxide (sc CO 2 ). Polymerization is controlled and proceeds at quasi the same rate as in toluene, which indicates that the reactivity of the propagating species is not impaired by parasitic carbonation reaction. Random copolymerization of LA with e-caprolactone (CL) has also been studied in sc CO 2 , and the reactivity ratios have been determined as 5.8 6 0.5 for LA and 0.7 6 0.25 for CL. These values have to be compared to 0.7 6 0.25 for LA and 0.15 6 0.05 for CL in toluene. Good control on ROP of CL and LA in sc CO 2 has been confirmed by the successful synthesis of diblock copolymers by sequential polymerization of CL and LA.

Controlled polymerisation and purification of branched poly(lactic acid) surfactants in supercritical carbon dioxide

“…ScCO 2 has been reported to strongly depress the melt temperature of L-lactide from ∼95°C to ∼50°C, 31,33,37 and through view cell studies we were able to visualise a similar trend for D,L-lactide, which has a higher T m (∼130°C). D-Sorbitol has an ambient T m of 95°C.…”

Copolymerization of D,L‐lactide and glycolide in supercritical carbon dioxide with zinc octoate as catalyst

“…There are few studies about the solubility of D,L ‐lactide and glycolide in scCO 2 . Qualitatively, it can be expected that the monomers are only slightly soluble in the scCO 2 and a great part of the initial 30 g of monomers will be nonsolubilized in CO 2 36, 38. Anyway it would be expected that the solubility of the monomers and low‐molecular‐weight compounds increases with pressure.…”

Ring-opening copolymerization of L-lactide and ɛ-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

“…Although PDMS-b-poly(methacrylic acid) and PDMS-b-poly(acrylic acid) formed discrete (PLLA) microparticles, acetylated PDMS-based copolymers could not stabilize the polymerization and produced hard agglomerates. Stassin and Jerome 24 reported the homopolymerization of LLA and copolymerization with e-CL in the presence of dibutyltin dimethoxide as an initiator. Random copolymers were synthesized, and the reactivity of monomers in scCO 2 was compared with that of monomers in toluene.…”