Temperature-responsive bending of a bilayer gel

Trends in polymeric shape memory hydrogels and hydrogel actuators

“…"Smart" hydrogels with controllable volume/shape changes in response to external physical or chemical/biochemical stimuli have become promising stars in developing mimetic actuators for controllably triggered manipulation. [68][69][70][71][72][73] In general, physical stimuli, including temperature, 74 electrical signals, 75 magnetic fields, 17 or mechanical stress, 76 alter molecular interactions at critical onset points. However, chemical stimuli, such as pH, 77 ionic factors, 78 and chemical agents, will change the interactions between polymer chains or between polymer chains and solvent at the molecular level.…”

Transformer Hydrogels: A Review

“…Upon activation, the soft swelling hydrogel starts to undergo isotropic volumetric expansion or contraction while the stiff hydrogel acts as a structural constraint opposing the active hydrogel layer. This mismatch between the hydrogel layers leads to a stress gradient through their thickness resulting in a bending deformation . The deformation mechanism and the degree of deformation depend on the shape, geometric parameters, and material properties of the hydrogel layers .…”

Quantifying the bending of bilayer temperature-sensitive hydrogels

“…In Cai's approach, the gel did not contribute to the bending stiffness of the beam [40]. Morimoto & Ashida [41] investigated the bending of a bilayer hydrogel consisting of a non-swellable layer and a temperature-sensitive hydrogel layer, and found that the predicted bending of the bilayer based on a finite-deformation theory was stronger than that based on a linear theory. Different from these previous works, here we consider a bilayer with both layers being temperature responsive and swellable.…”