Candida antarctica Lipase B-Catalyzed Synthesis of Poly(butylene succinate):  Shorter Chain Building Blocks Also Work

Abstract

Lipase catalysis was successfully employed to synthesize high molecular weight poly(butylene succinate) (PBS). Attempts to copolymerize succinic acid with 1,4-butanediol were unsuccessful due to phase separation of the reactants. To circumvent this problem, monophasic reaction mixtures were prepared from diethyl succinate and 1,4-butanediol. The reactions were studied in bulk as well as in solution. Of the organic solvents evaluated, diphenyl ether was preferred, giving higher molecular weight products. After 24 h in diphenyl ether, polymerizations at 60, 70, 80, and 90 degrees C yielded PBS with M(n) of 2000, 4000, 8000, and 7000, respectively. Further increase in reaction time to 72 h resulted in little or no further increase in M(n). However, increasing the reaction time produced PBS with extraordinarily low M(w)/M(n) due to the diffusion and reaction between low-molecular weight oligomers and chains that occurs at a greater frequency than interchain transesterification. Time-course studies and visual observation of polymerizations at 80 degrees C revealed PBS precipitates at 5 to 10 h, limiting the growth of chains. To maintain a monophasic reaction mixture, the polymerization temperature was increased from 80 to 95 degrees C after 21 h. The result was an increase in the PBS molecular weight to M(w) = 38 000 (M(w)/M(n) = 1.39). This work paves the way for the synthesis of PBS macromers and polymers that contain variable quantities of monomers with chemically sensitive moieties (e.g., silicone, epoxy, vinyl). Furthermore, this study established the feasibility of using lipase catalysis to prepare polyesters from alpha,omega-linear aliphatic diethyl ester/diol monomers with less than six carbons.

Chemoenzymatic synthesis of oleic acid‐based polyesters for use as highly stable biomaterials

“…It has been reported that Novozyme 435 could catalyze reactions at higher temperatures up to 90 8C. 24 However, the epoxide product is not stable at higher temperatures. As shown by the HPLC chromatograms in Figure 1, 100% conversion of oleic acid can be achieved within 5 h at 40 8C.…”

Enzymatic synthesis and preliminary evaluation as coating of sorbitol-based, hydroxy-functional polyesters with controlled molecular weights

“…To ensure that the reaction times required to prepare these polymers were not excessively long, all subsequent polymerizations were performed using 10 wt% Novozyme 435 Ò . Since the loading of CALB in the Novozyme 435 Ò preparation is only 10 wt%, the actual amount of CALB used in the reactions is 1 wt% [27].…”

A biocatalytic approach towards sustainable furanic–aliphatic polyesters

“…[33][34][35][36][37] In recent years, enzymatic synthesis of sustainable polyesters from biobased monomers has attracted much attention. 5,32 Plenty of biobased polyesters have been readily prepared via enzymatic polymerization, e.g., succinate-based aliphatic polyesters, [38][39][40] 1,4 : 3,6-dianhydrohexitol-based polyesters, 41,42 vegetal oilbased polyesters, 43 sugar derived diol-based polyesters, 44,45 etc. Recently we successfully synthesized a series of renewable 2,5-bis(hydroxymethyl)furan-based polyesters by two-stage enzymatic polycondensation in diphenyl ether.…”