Multifunctional NIPU films with intrinsic fluorescence

Conventional humidity sensors require complex processes and costly additives, and they cannot monitor how polymers change when exposed to water. Designing materials capable of detecting humidity while also providing information about their own structural state remains a major challenge.

To address this, Christophe Detrembleur (WEL Research Institute – ULiège) and his team developed non-isocyanate polyhydroxyurethane (NIPU) films with intrinsic fluorescence arising from clusteroluminescence, removing the need for any added fluorophores. The light intensity decreases linearly with relative humidity, directly correlating with polymer plasticization and the decrease in glass transition temperature. 

This work demonstrates the potential of NIPU films as stable, additive-free bifunctional sensors, capable of simultaneously detecting humidity and monitoring polymer softening in real time.

Reference: Mahapatra et al., Non-isocyanate polyurethane (NIPU) films for dual-function humidity sensing and hydroplasticization monitoring by harnessing clusteroluminescence, Adv Funct Mater (2025) e23095