Multiresponsive Bilayer Hydrogel Actuator with Switchable Shape Morphing Capability and Visible Color/Fluorescence...

Area of Science:

• Materials Science
• Polymer Chemistry
• Bioinspired Materials

Background:

• Bilayer hydrogels with multiresponsive and color-changing properties are crucial for bioinspired artificial intelligent materials.
• Mimicking the simultaneous adaptation of live organisms (shape, fluorescence, color) remains a significant challenge.

Purpose of the Study:

• To fabricate a multiresponsive and multiadaptive hydrogel capable of simultaneous changes in shape, fluorescent color, and visible color.
• To utilize specific monomers for pH-responsive fluorescence and switchable color change.

Main Methods:

• Fabricated a bilayer hydrogel using pH-responsive fluorescent monomer 4-(2-(4-(dimethylamino) phenyl)-1-isocyanovinyl) phenol (DP) and switchable color-changing monomer 4-(2-sulfethyl) -1-(4-vinylbenzyl) pyridinium betaine (VPES).
• Comprised two layers: a temperature- and pH-responsive poly(N-isopropylacrylamide-co-2-(dimethylamino) ethyl methacrylate) layer and a pH-, temperature-, and salt-responsive poly(acrylamide-co-2-(dimethylamino)ethyl methacrylate-co-VPES)@DP layer.
• Exploited opposite swelling/shrinking behaviors between layers for stimuli-induced shape changes.

Main Results:

• The hydrogel exhibited shape changes in response to temperature, salt, and pH stimuli.
• Achieved switchable fluorescent color changes originating from DP and visible color changes from polyVPES.
• Demonstrated excellent antifatigue properties and high sensitivity.

Conclusions:

• The developed bilayer hydrogel successfully mimics live organism adaptation through multiresponsive and multiadaptive behaviors.
• The fabrication strategy offers inspiration for designing advanced biomimetic smart materials.
• The hydrogel holds significant potential for diverse applications requiring smart material responses.