Interfacial materials such as particles, films, and self-assemblies are useful for medical, environmental, and energy applications due to their large specific surface areas and unique surface/interfacial properties. We have designed a variety of responsive interfacial materials with dynamic structures such as molecular complex cross-links, photodimerizable groups, and liquid crystalline phases to develop drug delivery systems, sensors, separation systems, etc. For example, polymer particles with molecular complex and disulfide crosslinks underwent size changes in response to a target molecule and a reducing environment. Stimuli-responsive gel films with molecular binding sites were formed on surface plasmon resonance and quartz microbalance sensor chips by molecular imprinting. An interpenetrating polymer network（IPN）consisting of temperatureresponsive poly （N-isopropyl acrylamide） and hydrophilic sodium alginate networks absorbed considerable moisture from the air at temperatures below its LCST and oozes the absorbed moisture as liquid water above its LCST. These phenomena allow us to harvest liquid water from the air. Temperature-responsive polymeric membranes and micelles were also designed using dynamic structures of liquid crystalline polymers（LCPs）．Amphiphilic LCPs, which undergo a liquid crystalline–isotropic phase transition at body temperature, formed temperature-responsive micelles that reversibly regulated drug release in response to temperature, without undergoing dissociation. This paper highlights our recent results on interfacial materials designed with dynamic structures and their applications.

The bond strength of metal/resin bonds under a wide range of strain rate was evaluated to investigate the strain rate dependence on the bond strength. This study conducted quasi-static tensile test, Split Hopkinson bar（SHB） test, and Laser shock-wave adhesion test（LaSAT）whose strain rate ranges from 10-3 to 107 s-1. It is found significant increase in bond strength with increasing strain rate. The fracture surface was mainly cohesive fractures, but the fracture initiation was observed at the interface near the edge. In order to investigate the surface modification effect for the adherend, anodic oxidation and silane coupling treatments were employed. From the above results, it is revealed that the increase in adhesive strength with strain rate is mainly dependent on the strength properties of the adhesive itself. To elucidate this mechanism, the relaxation due to the molecular chains deformation in the adhesive was theoretically investigated. The primary relaxation mechanism at low strain rate is dominated by the bending deformation of the molecular chains, while the secondary relaxation mechanism at high strain rate is dominated by the torsional deformation of the molecular chains. Therefore, we conducted tensile deformation simulation of bulk epoxy resin at high strain rate using molecular dynamics（MD）simulation, and found that the torsional deformation of molecular chains becomes significant in the secondary relaxation mechanism. Such a bifurcation of deformation of molecular chains leads a significant increase in bonding strength at high strain rate.

We have developed a simple and useful process for fabricating functional polymer and carbon materials modified with a variety of functionalities by surface photochemical modifications. The introduction of the functional moieties on the surface of these materials showed an improvement of their original properties while maintaining the bulk properties of polymer and carbon materials. We will also report on the nanocoating technology for the control of surface and interface functionality and for an application to joining of dissimilar materials with high joint strength for flexible printed circuits（FPC）in 5G networks.

Photoprocessable polymer network materials undergo changes in their shape and stiffness via the cleavage of covalent bonds in the polymer chains or cross-linkers under light irradiation. Owing to their high spatiotemporal resolution, they are used in various applications, including photolithography, drug delivery, and adhesives. Recently, various types of photoreactive moieties in the polymer networks have been developed, allowing low-energy, rapid, and reversible photoprocessing. Moreover, a new class of photoreactivity enables higher-order material control by utilizing multiple stimuli, in addition to light. The reactivity of materials to light can be tuned and switched by sequential or simultaneous treatments with chemical reagents. This sophisticated photoreactivity would expand the applications of photoprocessable materials because these materials can be used even in a lit environment without undesired photoreactions. In this review, we summarize the recent progress in photoprocessable polymer network materials based on the chemical cleavage of polymer chains under light, focusing on the molecular design of the photoreactive moieties.