CHEMOENZYMATIC SYNTHESIS OF LINEAR POLY(SUCROSE ACRYLATE) - OPTIMIZATION OF ENZYME-ACTIVITY AND POLYMERIZATION CONDITIONS

We have achieved significant improvements in the synthesis of poly(suc rose acrylate). A screen of 15 commercial enzymes was carried out and Alcalase 2T was selected as the best enzyme because of its high activi ty and selectivity for acylation of sucrose at only one site. The rate of the enzyme catalyzed acylation of sucrose to form sucrose 1'-acryl ate was increased by a factor of ca. 100 compared to previous reports. This rate was increased 10-fold by treating the as received enzyme by adjusting the pH to the optimum value for the enzyme. An additional 1 0-fold increase was achieved by adding a lyoprotectant such as sucrose or poly(ethylene glycol) prior to lyophilizing the enzyme. Significan tly higher molecular weights obtained in aqueous polymerization system s than when N,N-dimethylformamide (DMF) was used as the solvent. Simil arly, higher molecular weights were observed for oxidation/reduction t han for azo-type free radical initiators. We have demonstrated that co polymers of sucrose acrylate and acrylic acid are readily prepared. Fi nally, by optimization of the polymerization system, we have increased the number-average molecular weight of the poly(sucrose acrylate) fro m MBAR(n) = 54000 to molecular weights MBAR(n) as high as 2400000.