화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.122, No.11, 2957-2961, 2018
Anisotropic Self-Oscillating Reaction in Liquid Crystalline Nanosheet Hydrogels
Anisotropic chemical wave propagation of self-oscillating Belousov-Zhabotinsky (BZ) reaction was demonstrated in the poly(N-isopropylacrylamide) gel films embedded with macroscopically aligned liquid crystalline inorganic nanosheets. Although the average propagation rate of chemical wave (v) over bar was 3.56 mm min(-1) in the gels without nanosheets, the propagation was retarded in the gels with 1 wt % of nanosheets: (nu(parallel to)) over bar =1.89 mm min(-1) and (nu(perpendicular to)) over bar = 1.33 mm min(-1) along the direction parallel and perpendicular to the nanosheet planes, respectively. Thus, the wave propagation is anisotropic with the anisotropy ratio (nu(parallel to)/nu(perpendicular to)) over bar = 1.42 in these gels and the periodic patterns formed by the BZ reaction were concentric ellipses, different from circles seen in isotropic gels. Furthermore, the propagation rate and degree of anisotropy were controllable by nanosheet concentration. These phenomena can be explained that the diffusion of molecules inside the gel is effectively hindered along the direction perpendicular to the nanosheet planes due to the very large aspect ratio of the aligned nanosheets. The present systems will be applicable for anisotropic self-oscillating soft actuators with one-dimensional motions as well as for ideal model system of BZ reactions.