Lipase-Catalyzed Synthesis and Characterization of Poly(glycerol sebacate)

• Main Authors: Zhuoyuan Ning (9095587), Kening Lang (4335196), Ke Xia (303441), Robert J. Linhardt (710659), Richard A. Gross (1450531)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 1753
• Subjects: Biophysics; Biochemistry; Cell Biology; Genetics; Molecular Biology; Biotechnology; Inorganic Chemistry; Infectious Diseases; Computational Biology; Chemical Sciences not elsewhere classified; Physical Sciences not elsewhere classified; unique mechanical properties; revealed regular decreases; prepolymerization step conducted; narrower dispersity (<; homogeneous liquid substrate; 59 400 g; 13 800 g; 120 ° c; linked pgs matrices; catalyzed condensation polymerization; w </ sub; n </ sub; catalyzed pgs synthesis; 3 %; respectively; catalyzed synthesis; enrich pgs; >< sub; đ </; without formation; transition temperature; study demonstrated; solvent fractionation; sebacic acid; sebacate dimer; rubbery networks; reached 72; nonsolvent increased; nonfractionated product; molecular species; inversely dependent; gel fraction; enzyme addition; corresponding increases; chain lengths; chain ends; bulk leads; avoid gelation; also report; >) decreased; 67 h; 55 h; 24 h; Antarc*; Antarctica
• Online Access: https://doi.org/10.1021/acs.biomac.1c01351.s001

This study demonstrated that immobilized Candida antarctica lipase B (N435) catalysis in bulk leads to higher molecular weight poly­(glycerol sebacate), PGS, than self-catalyzed condensation polymerization. Since the glass-transition temperature, fragility, modulus, and strength for rubbery networks are inversely dependent on the concentration of chain ends, higher molecular weight PGS prepolymers will enable the preparation of cross-linked PGS matrices with unique mechanical properties. The evolution of molecular species during the prepolymerization step conducted at 120 °C for 24 h, prior to enzyme addition, revealed regular decreases in sebacic acid and glycerol-sebacate dimer with corresponding increases in oligomers with chain lengths from 3 to 7 units such that a homogeneous liquid substrate has resulted. At 67 h, for N435-catalyzed PGS synthesis, the carboxylic acid conversion reached 82% without formation of a gel fraction, and number-average molecular weight ( M n ) and weight-average molecular weight ( M w ) values reached 6000 and 59 400 g/mol, respectively. In contrast, self-catalyzed PGS condensation polymerizations required termination at 55 h to avoid gelation, reached 72% conversion, and M n and M w values of 2600 and 13 800 g/mol, respectively. We also report the extent that solvent fractionation can enrich PGS in higher molecular weight chains. The use of methanol as a nonsolvent increased M n and M w by 131.7 and 18.3%, respectively, and narrower dispersity ( Đ ) decreased by 47.7% relative to the nonfractionated product.