writer：Shuhui Liu,a,b Guorong Gao,a,b Ying Xiao,a,b and Jun Fu*,a,b
keywords：hydrogel, responsive, actuator, polyelectrolyte
source：期刊
specific source：J Mater Chem B
Issue time：2016年

Responsive nanocomposite (NC) hydrogels are widely recognized as strong and tough soft

materials for smart devices, but yet with challenges in the synthesis of such

hydrogels and the fabrication of devices. This work reports on a versatile

synthesis of nanocomposite polyelectrolyte hydrogels with high strength and

toughness by using either cationic or anionic monomers, and demonstrates a simple

and versatile fabrication of bilayer actuators by assembling the oppositely

charged hydrogels through electrostatic attraction. Herein, exfoliated sodium montmorillonite

(NaMMT) nanosheets were used as crosslinkers through adsorption of monomers and

initiators prior to in situ free radical polymerization. NC hydrogels with

negative charges were obtained by copolymerization of acrylamide (AAm) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), while positively charged NC gels were

obtained by using AAm and dimethylaminoethyl methacrylate methylchloride (DMC).

These NC polyelectrolyte hydrogels were responsive to pH, and ion strength of buffer

solutions, and showed outstanding fatigue resistance against cyclic compression

loadings, and high tensile strength and toughness. After tensile tests, the

gels were able to recover at room temperature. Moreover, the oppositely charged

hydrogels were assembled with robust interface based on electrostatic

attractions between the opposite charges. These hydrogels were actuated under

electric field. Besides, the oppositely charged hydrogels were assembled into

bilayers, which were reversibly actuated due to the contrasting responsiveness

of each gel to ion strength .