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ABSTRACT:Polyesters containing aromatic moiety in the main chain have been synthesized by enzymatic polymerization of dicarboxylic acid divinyl esters and glycols under mild reaction conditions. Divinyl esters of isophthalic acid, terephthalic acid, and p-phenylene diacetic acid, were used as new monomer for the enzymatic polymerization. Effects of the polymerization conditions were systematically investigated in the polymerization of divinyl isophthalatc and 1,6-hcxancdiol. Candida antarctica lipase afforded the polymer of the highest molecular weight. Methylene chain length of the glycol affected the polymer yield and molecular weight. Divinyl terephthalate was enzymatically polymerized under the similar reaction conditions, yielding the polymer of lower molecular weight. Enzymatic polymerization of divinyl sebacate and p-xylylene glycol also afforded the aromatic polyester.KEY WORDS Enzymatic Polymerization I Lipase I Aromatic Polyester I Divinyl Ester I Polycondensation I Aromatic polyesters, typically poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), are widely used in various fields since they have excellent properties, e.g., high thermal and chemical stabilities.1.2 These polymers are industrially produced at high temperature under reduced pressure. Since PET and PBT are not environmentally benign due to their low biodegradability, aliphatic and aromatic ester copolymers have been developed as new biodegradable engineering plastics. However, their synthesis also involved severe reaction conditions (high temperature and/or reduced pressure).Recently, hydrolase-catalyzed polymerizations have received much attention as environmentally friendly methodology of polyester syntheses owing to non-toxic enzyme catalyst and mild reaction conditions. 3 -7 In some cases, lipase showed unique catalytic behaviors for the polyester syntheses in comparison with those of conventional chemical catalysts. Lipase induced the ring-opening polymerization of small-and medium-size lactones as well as macrolides (12-, 13-, 16-, and 17-membered lactones). 8 -17 Using traditional chemical catalysts, the macrolides showed much lower reactivity and polymerizability than e-caprolactone (7-membered lactone, e-CL) due to their lower ring strain. 18 • 19 However, they were enzymatically polymerized much faster than e-CL, probably due to the stronger recognition of the macrolide by lipase. 13 -17 In lipase-catalyzed acylation for synthesis of functional organic products, vinyl esters have been often used as acylating agents because the irreversible tautomerization of the leaving vinyl alcohol group to acetaldehyde afforded the desired product in high yields. 20 • 21 We reported that divinyl adipate was superior to the corresponding diacid or dialkyl ester for the enzymatic synthesis of polyester. 22 Afterwards, several examples of the enzymatic polymerizations using divinyl esters were t To whom correspondence should be addressed. 380reported. 23 -25 Very recently, we have found that the lipase-catalyzed pol...

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