Water responsive biopolymers are gaining enormous attention in the different areas of research and applications related to self-folding. In this work, we report that cross-linking is an efficient means of modifying a single layer biopolymer film for a controlled and predictable pathway of folding. The initiation of the folding of a film is caused by the diffusion of water molecules along the film thickness. However, this folding is observed to take place in an unpredictable and random fashion with a pristine biopolymer film and a nano-particle reinforced film. The mechanical properties and the diffusion characteristics of the film are strongly interrelated and affect the overall folding behavior. The underlying mechanism behind this relation is appropriately substantiated by an in depth molecular dynamic study. The detailed characterization of the folding shape and material behavior is performed applying suitable experimental techniques. The potential application of the controlled folding of the cross-linked film as a sensor and as a soft crane is demonstrated in this report.

Nanostructures play a significant role in introducing distinctive functionality to materials. A synergistic combination of nanofabrication techniques with material properties holds great promise in creating smart biomimetic structures. An advanced preparation technique to fabricate complex and sophisticated hierarchical polymeric nanostructure templates via anodized alumina oxide membranes is highlighted. Moreover, nanostructures made of responsive polymers activated by environmental stimuli offer a huge potential in a wide range of applications by enhancing their responsiveness. The current state of research on novel nanostructures fabrication by integrating anodic aluminum oxide with stimuli‐responsive polymers is presented, with an emphasis on the underlying actuation mechanism in terms of application. Furthermore, the potential direction for future research is discussed.

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We report the controlled reversible and irreversible folding behavior of a biopolymer film simply by tuning the solvent characteristics. Generally, solvent triggered folding of soft membranes or film is achieved by unfolding. Here, we show that this unfolding behavior can be suppressed/delayed or even completely eliminated by altering the intrinsic nature of the solvent. A reversible folding of biopolymer film is observed in response to water, whereas, an irreversible folding is observed in the presence of an aromatic alcohol (AA) solution of different molar concentrations. The folding and unfolding behavior originates from the coupled deformation-diffusion phenomena. Our study indicates that the presence of an AA influences the relaxation behavior of polymer chains, which in turn affects the release of stored strain energy during folding. Controlling the reversibility as well as the actuation time of the biopolymer film by tuning the solvent is explained in detail at the bulk scale by applying appropriate experimental techniques. The underlying mechanism for the observed phenomena is complemented by performing a simulation study for a single polymer chain at the molecular length scale. Due to the solvent-triggered hygromorphic response, biopolymer films exhibit huge potential as sensors, soft robots, drug delivery agents, morphing medical devices and in biomedical applications. We provide experimental evidence for the weight lifting capacity of permanently folded membranes, amounting to ∼200 times their own weight.