| Popis: |
Controlling the shape change in responsive materials to external stimuli such as temperature, light, and pH attracts the attention of many fields including biomedical, tissue engineering, drug delivery, and soft robotics. Poly(N-isopropylacrylamide)P(NIPAm), a derivative of acrylamide, is one of the most widely used temperature responsive polymers. P(NIPAm) has hydrophobic and hydrophilic groups, so changes occur in its structure depending on the temperature. Aqueous solutions of P(NIPAm) swell by taking more water under the phase transition temperature (~32 °C), which is called lower critical solution temperature (LCST), and shrink by releasing the absorbed water above that temperature.By inspiring unique features of stimuli-responsive materials, we design a thermo-responsive trilayer hydrogel platform with different patterns and pattern colors. These hydrogel platforms are fabricated through crosslinking a non-responsive passive layer and two thermo-responsive active layers together in a 3D-printed mold. The difference in shrinkage between layers above the lower critical solution temperature (LCST) generates stress that results in the bending of the material. This bending is controlled by the external light stimulation of the responsive layer made in various patterns and colors. The colored upper layer absorbs the light in different degrees depending on the wavelength of light. This absorbance primarily provides the heating of the patterns and determines the folding direction. As proof of concept, the application of a design that gripes the target is also demonstrated. The results show that our approach might open up promising possibilities in the production of soft foldable materials. |
