Syntheses of poly(lactic acid)‐poly(ethylene glycol) serial biodegradable polymer materials via direct melt polycondensation and their characterization

Abstract

Directly starting from lactic acid (LA) and poly(ethylene glycol) (PEG), biodegradable material polylactic acid-polyethylene glycol (PLEG) was synthesized via melt copolycondensation. The optimal synthetic conditions, including prepolymerization method, catalyst kinds and quantity, copolymerization temperature and time, LA stereochemical configuration, feed weight ratio m LA /m PEG and M n of PEG, were all discussed in detail. 1 H NMR, GPC, DSC, XRD, and contact angle testing. d,l-PELG not only had higher MW than PDLLA, PLLA and l-PELG, but also better hydrophilicity than PDLLA. The novel one-step method could be an alternative route to the synthesis of hydrophilic drug delivery carrier PLEG instead of the traditional two-step method using lactide as intermediate.

Synthesis of poly(D,L‐lactic acid) modified by cholic acid via direct melt copolycondensation and its characterization

“…Its excellent biocompatibility and biological resorbability afford it extensive applications in biomedical fields, including sutures, bone fixation materials, drug-delivery microspheres, and tissue engineering. [1][2][3][4][5][6] To improve the performance of PLA, especially to promote its cell adhesion, many PLA copolymers, such as poly(lactic acidglycolic acid), 7 PLA-poly(ethylene glycol), 8 PLApoly(phosphate ester), 9 and poly(lactic acid-amino acid), 10 have been developed via the copolymerization of other functional molecules with lactic acid (LA) or lactide.…”

Synthesis of poly(D,L‐lactic acid) modified by triethanolamine by direct melt copolycondensation and its characterization

“…When the temperature was higher than 160 C, the side reactions such as oxidation and thermal degradation, especially the latter markedly took place. [13][14][15][16]23 So, the [g] decreased markedly…”

“…When the time was too shorter, polymerization was not sufficient. However, once the reaction time was longer than 8 h, the thermal degradation and/or oxidation of the polymer became serious, [13][14][15][16]23 which made the [g] dropped and the color of the purified product become yellow or brown. In these cases, 8 h was selected as the appropriate time in our experiments.…”

Preparation and characterization of poly(L‐lactide) membranes prepared by γ‐radiation‐induced grafting of N‐vinyl pyrrolidone

“…The contact angle decreased from 75.1 (graft ratio ¼ 0.0%) to 65. 3 (graft ratio ¼ 14.9%), which was attributed to the better hydrophilicity of the PVP chain.…”

“…1,2 However, the degradation rate of PLLA as an implantation material is comparatively low because of its high crystallinity percentage and poor hydrophilicity. 3,4 Conventionally, the copolymers of functionalized PLLA grafted by free-radical copolymerization with other monomers, such as N-vinyl pyrrolidone (NVP) and tert-butyl acrylate, have been prepared under a variety of conditions. [5][6][7] The degradation behavior of poly(lactic acid) grafted with methacrylate and oligo(D,L-lactide) grafted with dextrans has been tentatively investigated.…”