Nature-inspired thermo-responsive multifunctional membrane adaptively hybridized with PNIPAm and PPy

Specialized plant tissues, such as the epidermis of a leaf covered with stomata, consist of soft materials with deformability and electrochemical properties to achieve specific functions in response to various environmental stimuli. Stimulus-responsive hydrogels with electrochemical properties are good candidates for imitating such special functionalities in nature and thus have great potential in a wide range of academic and industrial applications. However, hydrogel-incorporated conductive materials are usually mechanically rigid, which limits their application in other fields. In addition, the fabrication technology of structured functional hydrogels has low reproducibility due to the required multistep processing. Here, inspired by nature, specifically the stimulus-responsive functionalities of plants, a new thermo-responsive multifunctional hybrid membrane (HM) is synthesized through the in situ hybridization of conductive poly(pyrrole) (PPy) on a photopolymerized poly(N-isopropylacrylamide) (PNIPAm) matrix. The morphological and electrical properties of the fabricated HM are investigated to characterize various aspects of its multiple functions. In terms of morphology, the HM can be easily fabricated into various structures by smartly utilizing photopolymerization patterning, and it exhibits thermo-responsive deformability. In terms of functionality, it exhibits various electrical and charge responses to thermal stimuli. This simple and efficient fabrication method can be used as a promising platform for fabricating a variety of functional devices. The mechanical response of a leaf to its environment has been replicated in a material synthesized by researchers in Korea. Materials developed to mimic solutions found in nature can enable novel functionalities. But most conventional bio-inspired systems recreate only simple structural changes using nonconductive hydrogels, while conductive materials are usually mechanically rigid. Inspired by the functional features of plants, Sang Joon Lee and co-workers from the Pohang University of Science and Technology have created a thermally responsive electrical membrane by combining two polymers – the organic polymer poly(pyrrole) and a photopolymerized poly(N-isopropylacrylamide) matrix. The membrane deforms when heated and its electrical properties and surface charge vary with temperature. The team considers that their simple and efficient fabrication method is a promising platform for fabricating various functional devices. Nature-inspired from the stimuli-responsive soft material in plants, multifunctional hybrid membrane with thermo-responsiveness and conductivity is synthesized by in situ formation of conductive PPy on a PNIPAm matrix. The hybrid membrane exhibits thermo-responsive electrical properties, thermo-responsive deformability, and a thermo-responsive charge effect. This simple yet efficient platform may open a new era of stimuli-responsive hydrogels to fabricate a variety of high performance electrical, electrochemical and biomedical devices