Polylactid-based (PLA) copolymer foams show a high potential for tissue engineering applications. However, tailored foam properties are required for these applications. As medical authorization is challenging for foams containing chemical modifiers or nucleating agents, tailored foam properties must be achieved by varying process parameters. Employing mixtures of supercritical CO2 and supercritical N2 as blowing agents is a promising approach to achieve tailored properties. In this study, the influence of CO2:N2 blowing agent mixtures on density, average cell size, open cell content, and storage stability is evaluated for PLA-based copolymer foams suitable for tissue engineering applications. Porosities higher than 90%, which are essential for sufficient cell ingrowth, could be achieved for all blowing agent mixtures. A decreasing average cell size was found for mixtures with low CO2 content. Improved storage stability and increased open cell contents were achieved for a CO2 to N2 volume ratio of 80:20.
Pongratz et al. (2025) studied this question.