Polycondensation in a spray of aqueous-alcoholic solution of lactic acid

Abstract

The removal of low molecular weight products of the reaction and heat withdrawal is one of the problems of bulk polycondensation. Polycondensation under spray conditions is an effective way to solve these problems. Based on the example of the reversible reaction of lactic acid polycondensation, it was shown that size effects can significantly affect the conversion rate, the degree of polymerization, and the rate of processes. Chemical thermodynamics suggests that chemical equilibrium in a spray shifts towards the formation of polylactide. In addition, the recondensation of volatile components (water, lactic acid, solvent) stabilizes the concentration of reagents and the temperature in the spray drops throughout the entire process. Model experiments confirming the obtained regularities are presented. Microscopic observation of sessile drops of aqueous and aqueous-alcoholic lactic acid solutions demonstrated the formation of polylactide under normal conditions (without heating, catalyst, evacuation).

Keywords

• polycondensation
• spray
• polylactide
• microencapsulation
• phase transitions