| This thesis is focused on reverse equilibrium polyester synthesis from multifunctional precursors using Candida antarctica lipase-B (CAL-B) as the catalyst.; In the first study, Lipase B from Candida antartica (CAL-B) immobilized on polyacrylate (lewatit) resin, catalyzed terpolymerizations of bis(hydroxymethyl)butyric acid, BHB (AB2) and 1,8-octanediol (B2) with adipic acid (A2). The copolymerizations of these AB2, B2, A2 monomers were conducted in bulk, at 80°C, without activation of the acid groups. Carbon ( 13C) NMR studies using a series of model BHB derivatives showed CAL-B was strictly selectivity for esterification of BHB hydroxyl groups while leaving the carboxylic acid unchanged. By varying the monomer feed ratio copolyesters with 9 to 45 mol % BHB-adipate units were formed with Mw values between 21,900 and 2,300 g/mol. Thermal and crystalline properties of the copolyesters were studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS).; In the second study, Immobilized Lipase B from Candida antartica (Novozyme 435) catalyzed bulk polycondensations at 70°C for 42 h that resulted in hyperbranched polyesters with octanediol-adipate and glycerol-adipate repeat units. Instead of using organic solvents, the monomers adipic acid (A2), 1,8-octanediol (B2), and glycerol (B'B2) were combined to form monophasic ternary mixtures. Variation of glycerol in the monomer feed gave copolymers with degree of branching (DB) from 9 to 58%.; Thirdly, hyperbranched aliphatic polyesters were synthesized by Novozyme 435 catalyzed terpolymerizations of Trimethylolpropane, (B3), and 1,8-octanediol, (B2) with adipic acid, (A2). The copolymerizations of these B3, B2, and A2 monomers were conducted in bulk, at 70°C, without activation of the acid groups. The degree of branching of the hyperbranched polyesters determined using inverse gated 13C NMR studies varied from 19% to 58%. |
