In this review, functional materials that are prepared from the rigid cylindrical inorganic polymer ‘imogolite’ and constructed in accordance with its structural characteristics are described. The combination of imogolite and dicarboxylic acids yields hydrogels that show a thixotropic response to mechanical shocks. The composition of the imogolite thixotropic gel and an ionic liquid gives a quasi-solid electrolyte that is moldable, thermally stable, and shows high ionic conductivity. The imogolite thixotropic gel shows physical anisotropy in respect to the orientation of the imogolite during flowing and subsequent standing. Macroscopic continuous helical ordering of imogolite achiral nanotubes is also achieved by thixotropic gelation of imogolite with a chiral hydroxy acid and their flow-orienting/subsequent standing for uniaxial alignment of imogolite. Furthermore, robust hydrogels are obtained by replacement of the dicarboxylic acid by polycarboxylic acids that show reversible isotropic–anisotropic structural transitions in response to strain.

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Beautiful patterns exist in natural materials, e.g., snow crystals, turbo spirals, and spatial partitions in plants such as fruits, flowers, and leaves (phyllotaxis) are well known. Here we ask the questions: How are they created? Why are they created? And, for what purpose are they created? These geometric patterns are formed through self-organization in natural environments. On the other hand, it is possible to artificially create spatial patterns as dissipative structures by using synthetic molecules in physicochemically controlled environments. In this study, several macropatterns of biopolymers in physicochemically controlled environments, i.e., in vitro, are introduced: teardrop patterns of microtubules, macrospace partitioning of microtubules, and that of polysaccharides from aqueous liquid crystalline states. These patterns result from the interfacial instability caused by the oriented states of the self-assembled microfibers at the air-liquid interface. By applying stress to the interface or drying the liquid from a limited space, the microfibers in the bundle states can be converted into patterns similar to those seen in living organisms, “from one space into multiple spaces”.

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The development of valuable functional materials using abundant and renewable resources has been recognized as one of the most important aspects to break out of the over-dependence on exhaustible fossil fuels. In nature, we can find a variety of organic compounds with unique molecular structures. The incorporation of interesting structural features of natural products into molecular designs is highly attractive for material development because it provides a new avenue for creating innovative functional materials that would be otherwise unimaginable. This review summarizes our latest studies on the synthesis of novel optically active polymers containing a structural element of naturally-occurring compounds, particularly (poly)saccharides, and their application to chiral functional materials.

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For preparating organic-inorganic or mesoporous inorganic materials via sol-gel condensation of a metal alkoxide, the combination of lyotropic liquid crystals (LLCs) and sol-gel chemistry is a versatile tool to fabricate various nanostructures. Despite the large number of accumulated investigations, no attempt has been made to use dynamic switching functions of such nanostructures via phase transition of the LLCs in a film. Recently, a polysiloxane containing an amine-hydrochloride group and a vinyl group was synthesized. By controlling the relative humidity, we achieve a phase transition of the LLCs and on-demand UV-curing of the LLC phases in the polysiloxane film. We further achieved vertical orientation of organic-inorganic nanochannels by using ππ interaction between a discotic molecule and the substrate surface or spontaneous vertical alignment of the LLC containing azobenzene unit.

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Induction of cancer-specific cellular immunity is necessary for establishment of cancer immunotherapy. For induction of cellular immunity, antigen delivery to immunocompetent cells such as dendritic cells and activation of these cells into a suitable state for immunity-induction are required. Here, intracellular antigen delivery systems have been developed using antigen-loaded liposomes modified with pH-responsive fusogenic polymers. Furthermore, polysaccharide-based pH-responsive polymers have been synthesized by introduction of carboxylated moieties to utilize polysaccharide-derived immunity-activation functions. Polysaccharide derivative-modified liposomes were taken up by dendritic cells efficiently and achieved cytoplasmic delivery of antigenic proteins via membrane fusion with endosomal membranes responding to weakly acidic pH in endosomes. After subcutaneous administration of these liposomes to mice, antigen-specific cellular immunity was induced by cytoplasmic delivery of antigen and activation property of immune cells derived from the polysaccharide backbone. In addition, combination of polysaccharide derivative-modified liposomes and TGF-β signaling inhibitor-embedded PEG-modified liposomes induced strong antitumor effects in tumor-bearing mice through induction of cellular immunity and cancelling of immunosuppression by the tumor.

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The termination reaction mechanism of radical polymerization and the control of the reaction for synthetic applications are studied by the reactions of structurally well-defined polymer end radicals prepared by living radical polymerization. The termination mechanism, namely the selectivity of disproportionation and combination of radicals, of representative monomers was determined unambiguously, and the effects of the reaction temperature, the molecular weight, and the solvent viscosity were clarified. In addition, the selective combination termination as a useful inter-polymer radical coupling reaction was developed.

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One capturing material can be used for various purposes. For example, the material for capturing analytes, harmful elements, and biomarkers can be used for pretreatment, decontamination, and diagnosis, respectively. The only difference is the target-capture molecules. A large part of the material design strategy can be common. To effectively and quickly develop novel capturing materials, we utilized radiation-induced graft polymerization by selecting the substrate for grafting from the point of view of chemical engineering, applying the desired graft polymerization, and performing subsequent chemical reactions. In this paper, a novel method for determining the mole percentage of an as-formed polymer brush and root is introduced as a new technique for evaluating grafted materials. In addition, according to the above determination technique, an extractant-impregnated porous sheet for rapid analysis and extractant-impregnated non-porous particle for high-resolution separation of rare earth elements were developed. We also developed metal ferrocyanide-impregnated fibers for radioactive cesium removal and a surface-functionalized power-free microfluidic chip for biomarker detection.

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Over-1000 nm near-infrared (OTN-NIR) fluorescent probes have recently attracted significant attention as in vivo fluorescence bioimaging agent, due to the high permeability of NIR light in this wavelength region for living tissue. In the past decade, I designed and reported various polymer conjugated OTN-NIR fluorescent probes such as rare-earth doped ceramic nanoparticles and organic dyes for deep tissue in vivo fluorescence bioimaging. This paper describes recent progress in research into the use of polymer conjugated fluorescent probes for OTN-NIR fluorescence in vivo bioimaging, most of which has been performed by our group.

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