Preparation And Performance Of Self-oscillating Gel With Different Ruthenium(â…¡)Catalysts Grafted By Acrylamide Groups

Self-oscillating gel, as an intelligent soft material, which is composed of a macromolecule chain with the catalyst of BZ oscillating reaction, Ru(bpy)32+ moieties, covalently bonded, can exhibit swelling and shrinking oscillations without any external stimulation. It has created a great potential in many research fields such as biomedical, tissue engineering and biomimetic materials.In order to build the novel self-oscillating gel, from the perspective of the selfoscillating catalysts, six kinds of Ru(bpy)32+ with different numbers from one to six of acrylamide substituents as polymerizable double bond groups were designed and synthesized. Furthermore, the performance of the catalysts series and its selfoscillating gel were researched and analyzed.Based on the idea of creating active cross-linker through the catalysts with more double bond group, we design and synthesized two kinds of bipyridine moieties with different numbers of double bond substituents: bipyridine with one acrylamide substituent and bipyridine with two acrylamide substituents. Then by combining the different kinds of bipydine, six types of Ru(bpy)32+ with the different numbers of acrylamide substituents were synthesized using a modular synthesis method. By the electrochemical cyclic voltamogram and the homogeneous BZ reaction dynamic measurement, the redox ability and catalytic performance of different kinds of catalysts were analyzed. It was found that those six kinds of catalysts with different numbers of double bond groups was able to catalyze the BZ reaction for a long time. However, the catalysts with one, two and four double bond groups performed the remarkable redox peaks and the larger amplitudes of BZ oscillating reaction, the catalysts with three, five and six double bond groups are less effective in those two area.The corresponding self-oscillating gel systems with above six kinds of synthetic catalysts were built. The gel were prepared by controlling the type and the content of above catalysts. It is demonstrated that the catalysts would be as the active crosslinkers when the number of double bond grafted group are no less than three. Then the self-oscillating gel with different types and contents of catalysts grafted different number of groups were characterized by means from redox behaviors and the degree of crosslinking. The larger density of volume gel present unapparent redox-responsive behaviors. The number of grafted group in the catalysts can control the crosslinking density of gel effectively. Finally, the thermosenstive performance of gel was measured and present the novel phenomena which is difference with the conventional gel: volume difference between oxidized state and reduced state is small in lower temperature but increase in higher temperature. In the meanwhile, the gel with one acrylamide group present 30% equilibrium swelling ratio in 24 oC and with the temperature increased, the gel with the catalysts grafted by three amide groups bear two times volumetric reversal between oxidized state and reduced state.