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Synthesis and characterization of the biomaterial poly(lactic acid‐ co ‐ N ε ‐carbobenzoyloxy‐ L ‐lysine) via direct melt copolymerization
Author(s) -
Ye Ruirong,
Wang Zhaoyang,
Luo Shihe,
Yang Liting,
Xiao Xin
Publication year - 2011
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.33621
Subject(s) - dispersity , copolymer , polymer chemistry , gel permeation chromatography , differential scanning calorimetry , condensation polymer , intrinsic viscosity , polymerization , monomer , molar mass distribution , materials science , glass transition , ring opening polymerization , lactic acid , chemistry , polymer , organic chemistry , physics , genetics , biology , bacteria , thermodynamics
With D,L ‐lactic acid and N ϵ ‐carbobenzoyloxy‐ L ‐lysine [Lys(Z)] as the starting monomer material and tin dichloride as the catalyst, the drug carrier material poly(lactic acid‐ co ‐ N ϵ ‐carbobenzoyloxy‐ L ‐lysine) was synthesized via direct melt polycondensation. The copolymer was systematically characterized with intrinsic viscosity testing, Fourier transform infrared spectroscopy, 1 H‐NMR, gel permeation chromatography, differential scanning calorimetry, and X‐ray diffraction. The influences of different feed molar ratios were examined. With increasing molar feed content of Lys(Z), the intrinsic viscosity, weight‐average molecular weight, and polydispersity index (weight‐average molecular weight/number‐average molecular weight) gradually decreased. Because of the introduction of Lys(Z) with a big aromatic ring into the copolymer, the glass‐transition temperature gradually increased with increasing feed charge of Lys(Z), and all of the copolymers were amorphous. The copolymers, with weight‐average molecular weights from 10,500 to 6900 Da, were obtained and could reach the molecular weight level of poly(lactic acid) modified by Lys(Z) via the ring‐opening polymerization of the cyclic intermediates, such as lactide and morpholine‐2,5‐dione. However, a few terminal carboxyl groups might have been deprotected during the polymerization reaction under high temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011