Poligromorph materials: Shape Morphing Functional Polyvinyl Alcohol/Maleic Anhydride Ethylene-Propylene/Carbon Composites in Aqueous and Hydrocarbon-Based Media

Hygromorphic materials and composites adjust their shape and curvature in response to changes in relative humidity, similar to the pinecone scales existing in nature. This work introduces a new class of poligromorphic materials - composites that adapt across various environments, including water, humidity, and hydrocarbons. Composed of carbon fibres (CF), polyvinyl alcohol (PVA), and maleic anhydride ethylene-propylene (MA-EPR) matrices, these materials are sensitive to fluctuations in fluids like water, isooctane and toluene. Their bioinspired internal architecture mimics the asymmetric stacking of pinecone scales. MA-EPR/CF composites show limited actuation in water but strong responsiveness in isooctane and toluene. PVA/CF materials are more sensitive to water while retaining functionality in hydrocarbons. Importantly, their actuation is reversible and stable through multiple cycles of environmental ageing, and the carbon fibres provide significant load-bearing capabilities, with stiffening effects when passing from dry to wet and immersed states.