Optimizing the bulk copolymerization of D, L-lactide and glycolide by response surface methodology

Poly(D, L-lactide-co-glycolide), PLGA, is a biodegradable polyester with high interest in medical industry, especially when zinc (II) 2-ethylhexanoate (ZnOct(2)) is used as catalyst substitute in polymerization processes as a substitute of the toxic tin (II) 2-ethylhexanoate (SnOct(2)) together an initiator such as methanol to improve the reaction rate. This article shows the optimization of the bulk copolymerization method by using a factorial design approach on three experimental parameters: temperature (T), molar ratio monomers/catalyst (MC ratio) and molar ratio initiator/catalyst (IC ratio). Their influence on mass conversion (X) and number-average molecular weight (M-n) was also discussed. Also it provides a useful tool to select in a fast way the proper experimental conditions for the obtaining of this polymer as a previous stage in the synthesis and impregnation of biodegradable scaffolds. This analysis revealed that the most relevant variable in the process is the temperature, being desirable to use the high value (160 degrees C) in order to obtain high values of conversion and molecular weight.