Dispersion polymerization of L-lactide/ε-caprolactone in supercritical carbon dioxide

The dispersion polymerization of L-lactide(LA) /ε-caprolactone(CL) with stannous octoate (Sn(Oct) 2 ) as a catalyst and n-butanol as an initiator in supercritical carbon dioxide (ScCO 2 ) was studied. The effects of operating parameters, such as pressure, temperature, stirring rate and monomer rate of LA/CL, on the characteristics of L-lactide and ε- caprolactone copolymer (PCLA) were investigated. The experimental results show that the pressure has the greatest effect on the morphology of the copolymer, and the temperature is the most decisive factor in the conversion ratio of the monomer. The changes of the conversion rate of the monomer were observed when the temperature risen from 90 to 110 °C. At the pressure of 18 MPa, the best morphology of the product can be got. Under the optimum reaction condition, PCLA with various ratio of LA/CL were obtained. Finally, fine powder particles of L-lactide and ε-caprolactone copolymer (PCLA) with high molecular weight were obtained.