Azim Himanshu, Dekhterman Alex, Jiang Zhaozhong, Gross Richard A
NSF I/UCRC for Biocatalysis and Bioprocessing of Macromolecules, Department of Chemical and Biological Sciences, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201, USA.
Biomacromolecules. 2006 Nov;7(11):3093-7. doi: 10.1021/bm060574h.
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.
脂肪酶催化已成功用于合成高分子量聚丁二酸丁二醇酯（PBS）。由于反应物的相分离，将琥珀酸与1,4 - 丁二醇共聚的尝试未成功。为解决此问题，由琥珀酸二乙酯和1,4 - 丁二醇制备单相反应混合物。对反应进行了本体和溶液研究。在所评估的有机溶剂中，二苯醚是优选的，可得到更高分子量的产物。在二苯醚中反应24小时后，60、70、80和90℃下的聚合反应分别得到Mn为2000、4000、8000和7000的PBS。将反应时间进一步延长至72小时，Mn几乎不再增加或没有进一步增加。然而，由于低分子量低聚物与链之间的扩散和反应比链间酯交换更频繁地发生，延长反应时间会产生Mw/Mn极低的PBS。80℃下聚合反应的时间进程研究和可视化观察表明，PBS在5至10小时沉淀，限制了链的生长。为保持单相反应混合物，21小时后将聚合温度从80℃提高到95℃。结果是PBS分子量增加到Mw = 38000（Mw/Mn = 1.39）。这项工作为合成含有可变数量具有化学敏感基团（如硅氧烷、环氧、乙烯基）单体的PBS大分子单体和聚合物铺平了道路。此外，本研究确定了使用脂肪酶催化由碳数少于六个的α,ω - 线性脂肪族二乙酯/二醇单体制备聚酯的可行性。
