Tough and Responsive Oppositely Charged Nanocomposite Hydrogels for Assembled Bilayer Actuators Through Interfacial Electrostatic Attractions
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 .