Flow-orientation of internal structure and anisotropic properties on hydrogels consisted of imogolite hollow nanofibers

Abstract

A thixotropic gel consisted of the mixture of imogolite (IG) and maleic acid could be liquefied and resolidified reversibly by shaking and standing, respectively, within subseconds (K. Shikinaka et al., Small, 10(9), 1813 (2014)). After flow-orienting and subsequent standing the sol-state mixture, the uniaxial alignments of IG hollow nanofibers with centimeter scale were realized in the recovered gel. The degree of orientation of IG was noticed to be dependent on the flow velocity of the sol-state mixture. The self-standing interpenetrated network gels with the desired shapes were prepared by the in situ polymerization of the uniaxially oriented gels that were pre-impregnated by 2-hydroxyethyl acrylate and a cross-linker. The confinement of the IG hollow nanofibers with the uniaxial orientation induced some anisotropic physical properties to the gels such as anisotropic proton conductivity and mechanical strength.