Candida antarctica as catalyst for polycaprolactone synthesis: effect of temperature and solvents

The effects of temperature on ring-opening bulk polymerizations of epsilon-caprolactone were studied by using lipase Novozyme-435 (immobilized form of lipase B from Candida antarctica), as biocatalyst. The polymerization of e-caprolactone was carried out at 50, 60, 70, 80, 90, and 100 degrees C. For Novozyme-435 the results showed that increasing the reaction time of the polymerization system resulted in an increased rate of monomer consumption and hence increased molecular weight. For an increase in reaction time, the conversion increases steadily and after a gradual increase there is a decrease, which is found to be uniform for all the temperatures showing a uniform trend. For a temperature of 70 degrees C and 4 h, molecular weight was found to be 8.4 x 10(4) daltons, which was the highest of all the readings that were obtained. A series of solvents including isopropyl ether, isooctane, and toluene were evaluated at 50, 60, 70, 80, 90, and 100 degrees C. Subjecting the data to the bootstrap resampling neural network modeling technique, it is shown that the actual and predicted value is more or less the same or in good agreement. The performance of neural network modeling capability, which is generally assessed by r value for validation data, is found to be 0.996. (C) 2011 Curtin University of Technology and John Wiley & Sons, Ltd.