Supercritical carbon dioxide (scCO₂) is a widely applied solvent utilized in many physical–chemical processes, including the foaming or structuring of polymers. Here, we demonstrate that the last two can be combined in one process step applying an incomplete saturation strategy, resulting in foamed and structured polymer sheets with multi-functionality. Caused by the nano- and micropores, the polymer sheets scatter light, leading to a white color impression. Due to the imprinted nano- and microstructures, the polymer surfaces feature an increased water contact angle and reduced optical reflection due to the moth-eye effect.
Borgmann et al. (2026) studied this question.