Study Of The Environment-sensitivity Of Macroscopically Self-assembly Hydrogel Through Molecular Recognition

In this study, a novel macroscopically self-assembly hydrogel was prepared through molecular recognition. Directly combination of two individual hydrogel with different environment sensitivity was proposed. The obtained bigel possessed a macroscopically heterogeneous structure and could perform a tunable bending behavior in response to a stimulus.Firstly, temperature-sensitive self-assembly bigel was synthesized. N-isopropyl acrylamide and6-acrylamide-β-cyclodextrin were copolymerized to be a host gel. Acrylamide and acrylamide-amantadine were copolymerized to be a guest gel. Based on the macroscopically host-guest complexation between (3-cyclodextrin and amantadine moiety, these two gels would form a self-assembly bigel. When the ambient temperature was higher than lower critical solution temperature (LCST), the obtained bigel could perform a bending behavior, because of the different temperature sensitivity between host gel and guest gel. The bending behavior was tunable by the ambient temperature, the molar ratio of6-acrylamide-p-cyclodextrin comonomer and the addition of PVA.Secondly, a kind of pH-sensitive self-assembly bigel was synthesized. The guest gel was prepared as the former. The host gel was prepared via copolymerization of acrylamide,6-acrylamide-β-cyclodextrin and methacrylic acid (MAA). These two gels with different pH sensitivity would form a self-assembly bigel through molecular recognition. The resulted bigel was immersed in buffer solution of different pH value. When the pH value was low, the bigel could bend; When the pH value was raised, the bigel would recover its’original shape. Similarly, the bending behavior of the pH-sensitive self-assembly bigel could be tuned by adjusting the pH value and the content of methacrylic acid monomer.The method we proposed to construct a smart bigel through macroscopically self-assemble possesses many advantages such as simple process of the sample preparation, arbitrarily combination of gels with different shapes, possibility to perform more complicated shape changes, reversible transition between adherence and separation, and so on. On the other hand, hydrogels of various functions or structures, ether porous or dense, with different kinds of sensitivities could be combined, and this might bring great opportunities to broaden and expand the application of hydrogels.