ENZYMATIC POLYESTERIFICATION IN ORGANIC MEDIA - ENZYME-CATALYZED SYNTHESIS OF LINEAR POLYESTERS .1. CONDENSATION POLYMERIZATION OF LINEAR HYDROXYESTERS .2. RING-OPENING POLYMERIZATION OF EPSILON-CAPROLACTONE

被引:221
作者
KNANI, D [1 ]
GUTMAN, AL [1 ]
KOHN, DH [1 ]
机构
[1] TECHNION ISRAEL INST TECHNOL,DEPT CHEM,IL-32000 HAIFA,ISRAEL
关键词
ENZYMATIC POLYMERIZATION; ORGANIC SOLVENTS; POLYESTERS; MACROLACTONES;
D O I
10.1002/pola.1993.080310518
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
With the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated: (1) the condensation polymerization of linear omega-hydroxyesters and (2) the ring-opening polymerization of lactones. The commercially-available crude porcine pancreatic lipase (PPL), suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6-hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzyme-catalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film-forming polyesters with a degree of polymerization (DP) up to about 100 were obtained from linear aliphatic hydroxyesters in n - hexane at reflux temperature (69-degrees-C). Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring-opening polymerization of lactones the reaction of epsilon-caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a DP of up to 35 were obtained in n-hexane at temperatures between 25 and 40-degrees-C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the H-1-NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity.
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页码:1221 / 1232
页数:12
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