私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

當前位置: 首頁 >> 產業發展 >> 正文

Enzyme-catalyzed preparation of aliphatic polythioester and its transformation into cyclic oligomers

時間:2004-12-07
關鍵詞:Enzyme catalyzed preparation aliphatic polythioester its transformation cyclic oligomers 來源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004

 

M. Kato, K. Toshima, and S. Matsumura1,*

 Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, JAPAN

 

Keywords: Enzyme-catalyzed polymerization, polythioesters, lipase, mercaptoalkanoic acid, degradation

Microbial polyesters containing thioester linkages in their backbone were recently reported by Lüke-Eversloh and Steinbüchel et al. for the first time and comprise a novel class of biopolymer. Microbial homopolymers of polythioester show some unique characteristics such as high melting point and poor solubility against various solvents. The synthetic polythioester has been reported fifty years ago, but commercial production of the polythioester has not been established partially due to the complex preparation methods. In this report, a more straightforward method, the novel lipase-catalyzed preparation of polythioester by the polymerization of 11-mercaptoundecanoic acid (11MU) and its transformation into cyclic oligomers is described.

 

          

11MU was polymerized by using immobilized lipase from Candida antarctica (lipase CA) to afford poly(11MU). As a typical example, poly(11MU) having an Mw of 31,000 was obtained quantitatively by lipase CA at 110 °C in bulk for 3 days under the existence of molecular sieves 4Å as a water absorbent. This is the first example to obtain a relatively high molecular weight homopolythioester using an enzyme. The thermal properties of poly(11MU) have been compared with those of poly(11-hydroxyundecanoic acid) to evaluate the effect of the thioester linkages in the polymer backbone.

The obtained poly(11MU) was readily degraded by lipase CA at 110 °C in n-octane to produce the corresponding cyclic oligomers having a molecular weight of few hundreds. The degradation was mainly dependent on reaction conditions such as polymer concentration, organic solvent, and reaction temperature. The repolymerization of these oligomers was also studied. Based on these results, it is highly expected that this type of novel polymer can be chemically recycled by using the reversible reaction of the enzyme.

 

論文來源:International Symposium on Biological Polyesters ,Auguest 22-27, 2004

主站蜘蛛池模板: 博野县| 海安县| 台中市| 和硕县| 濮阳市| 陆良县| 蒙自县| 祁东县| 库伦旗| 府谷县| 凉城县| 凤阳县| 吴桥县| 龙海市| 谷城县| 信宜市| 城口县| 秭归县| 金堂县| 惠州市| 志丹县| 昌吉市| 威海市| 盐津县| 巴塘县| 福贡县| 陕西省| 马尔康县| 高邑县| 西青区| 哈尔滨市| 泰州市| 亚东县| 吉木乃县| 谷城县| 韶山市| 镶黄旗| 松阳县| 惠来县| 方城县| 宣城市|