Towards sustainable food packaging: Optimization of suitable sorbitan surfactant for the development of PLA-based antifog film

The demand for sustainable and biodegradable materials for food packaging applications is on the rise due to the environmental issues caused by plastic pollution. Sustainability and compostability, coupled with transparency and film-forming ability, make polylactic acid (PLA) a suitable material for antifog film applications. However, large-scale use of PLA as antifog film remains a challenge due to its inability to prevent the formation of water droplets on its surface. Here, we attempt to overcome this issue by blending PLA with a suitable sorbitan-based non-ionic surfactant, which increases its surface-free energy and wettability. Among various sorbitan-based surfactants, sorbitan monopalmitate (Span 40) was found to be more efficient in promoting good wetting and, thereby, preventing the formation of foggy droplets. The additive concentration and extrusion film-blowing parameters for PLA were optimized. The increase in surface free energy of these films was confirmed by measuring contact angle and fog testing. The results revealed that the incorporation of Span 40 significantly improved the antifogging performance of PLA films without affecting transparency, making them suitable for environmentally friendly antifog film applications. The findings presented here could pave the way for developing and commercializing PLA-based antifog films without any additional coating or surface modification requirements.