Sorption and swelling of poly(DL-lactic acid) and poly(lactic-co-glycolic acid) in supercritical CO2:: An experimental and modeling study

Tissue engineering scaffolds require a controlled pore size and structure to host tissue formation from cell populations. Supercritical carbon dioxide (scCO(2)) processing can be used to form porous scaffolds in which the escape of CO2 from a plasticized polymer melt generates gas bubbles that shape the pores. The process is difficult to control with respect to changes in final pore size, porosity, and interconnectivity, while the solubility of CO2 in the polymers strongly affects the foaming process. An indepth understanding of polymer CO2 interaction will enable a successful scaffold processing. Amorphous poly(DL-lactic acid) (P(DL)LA) and poly(lactic acid-co-glycolic acid) (PLGA) polymers are attractive candidates for fabricating scaffolds. In this study, CO2 sorption and swelling isotherms at 35 degrees C and up to 200 bar on a variety of homo- and copolymers of lactic acid and glycolic acids are presented. Sorption is measured through a gravimetric technique using a suspension microbalance and swelling by visualization. The obtained results are modeled using the Sanchez-Lacombe equation of state. (C) 2008 Wiley Periodicals, Inc.