In this proposal, we present a concept common to all materials based on the mechanical properties of materials that exceeds existing frameworks for present structural materials, functional materials, organic materials, inorganic materials, metallic materials, and semiconductor materials. We propose research and development strategies aiming at establishing novel guidelines for materials design and innovation by elucidating the macroscopic mechanical properties through an understanding of diverse phenomena at the nanoscale.

The top export items in Japan are occupied by materials, devices and related products such as automobiles, electronic components including semiconductors, steel, motors, plastics, organic compounds, and optical equipment for scientific research. It is the present status of Japan that the materials industries, electrical/electronical industries, and the machinery industries sustain economy of this country.

In recent years, demands for realizing a sustainable society through reducing CO₂ emissions and saving energies are increasing, and extracting the potential of materials and devices to the utmost is being highly required. In fact, in the transportation equipment, such as automobiles and airplane, higher fuel-efficiency, i.e. lower CO₂ emission is highly demanded by introducing lighter-weight and higher-strength materials for their bodies. In the electronic devices, although the limitation of Moore's law has become apparent, global demand for semiconductors has been also increasing due to the appearance of IoT and artificial intelligence (AI), and accelerating development of self-driving, etc. In these movements, it is strongly desired to realize higher integration, higher performance and higher function of semiconductor chips.

In addition, social infrastructure such as bridges and expressways constructed intensively during the period of high economic growth in Japan has already been 50 years since the construction, and its safety has become a serious social issue.

In order to satisfy such social demands, we should return to the nanoscale structure of materials to clarify the mechanism of complex phenomena appearing in the materials including non-equilibrium, dissipative, and unsteady state ones, which had been difficult to handle so far. Furthermore, it becomes necessary to establish a comprehensive analytical method based on a trans-scale approach that enables the understanding of mesoscale and macroscale phenomena from the nanoscale mechanisms. These approaches will make it possible to establish new materials design guidelines, by which development of innovative materials with high and novel functionalities that may not be realized with existing materials will become possible through the development of controlling technology for macroscopic material properties, and evaluation technology related to lifetime, reliability, and durability.

In this proposal, we take up "adhesion / bonding / removing", "friction / fatigue", and "self-repairing" as strong social demands from a wide range of technology fields concerning macroscopic mechanical properties.

Improvement of fuel efficiency in transportation equipment, automobiles in particular, is strongly demanded to reduce CO₂ emission. From such a standpoint, "light weight", "high strength" and "multi-materialization" are important technical elements to be developed. For example, carbon fiber reinforced plastic (CFRP), which is representative of lightweight and high strength material, is used only partially in the transportation equipment due to a high manufacturing cost, difficulty in forming, difficulty in securing reliability quantitatively. In order to overcome such a situation, it is important to understand the material properties from the nanoscale. For further reduction of the weight of the car body, multi-materialization where different materials are adhered and bonded is required. For this purpose, it is indispensable to elucidate the intrinsic adhesion mechanism at bonding interface.

Bonding technology is also important in semiconductor devices, including solar cells and three dimensional integrated circuits. As expectations for solar cells, which is an effective renewable energy source as a measure to mitigate global warming, are rising, low cost and high efficiency of solar cells are strongly desired. In order to meet the needs, multijunction systems that laminate in three-dimensional direction are attracting attention. In addition, three-dimensional stacking of semiconductor integrated circuits is expected to execute an information processing of large amount of data with high speed and low power consumption, since it becomes physically difficult to increase the integration density in the 2-dimensional plane due to the limits of Moore's law for semiconductor devices. In these applications, sophistication of bonding technology for three-dimensional integration of plural semiconductor elements is required in order to realize higher integration and higher performance of semiconductor devices, and to enhance their function.

Another important element to improve fuel efficiency in transportation and mechanical equipment is "friction / fatigue", and it is expected that elucidation of the mechanisms in these phenomena leads to reduction of energy loss of various mechanical devices and decrease of their failure frequency.

"Self-repairing" attracts interest as a main research subject for special applications such as instruments used in space that are difficult to repair artificially and equipment used in advanced fields such as turbine engines in the aircraft. Recently, the target has been expanding to repair scratches and dents of the equipment familiarly used in our daily life, such as car painting, smartphone housing, and the display screen. In addition, it is expected to add self-restoring capability to social infrastructures such as aging bridges as a way to extend their lifetime. Basic understanding of the mechanism of self-repairing function is needed as a common issue to these cases, even though the reaction rate and the condition to arise the repairing process differ depending on the application as described above.

Under such background, it is important not only to overcome individual problems concerning "adhesion/bonding/removing", "friction/fatigue", and "self-repairing", but also to establish a new theoretical framework and simulation technology that enables understanding of these phenomena from the nanoscale considering the physics of nonequilibrium, dissipation, and non-steady state, and leads to the understanding of the dynamic characteristics on the macroscale. In order to provide technical solutions to these requirements, it is necessary to make clear various research and development tasks centering on "construction of the theoretical principle for trans-scale mechanics", "construction of trans-scale mechanical simulation technology" and "development of operando measurement/ evaluation technology of nanostructure and macrostructure", and to establish a trans-scale approach to analyze comprehensively what is going on at the nanoscale and how it is connected to the mesoscale and macroscale phenomena, by getting over the scale barriers.

In conducting research and development of this proposal, scientists and engineers of relevant industry, academia, and government on the nanoscale side and the macroscale side should share the issues to be tackled collaboratively and goals to be realized toward building a sustainable society, and construct a forum where those scientists and engineers gather and discuss them, and establish a network environment that enables information sharing among those scientists and engineers.

Traditionally, scientists who have a mission of elucidating the origin of material properties at the nanoscale, such as chemists and physicists, have a tendency to pursue the ultimate performance of the materials even though it is realized only under special conditions, and to conduct research and development without full consideration of other requirements such as their reliability, durability, and mass productivity. On the other hand, researchers in the field such as mechanical engineering and fluid engineering who deal with macroscale mechanical characteristics put stress on achieving the best performance in a given environment under the condition of required reliability and durability, rather than pursuing the ultimate performance of the materials. As described above, since the direction and the way of conducting research differs basically in those fields, almost all of trans-scale collaboration and integration connecting these different fields have not advanced. In order to overcome this situation, it is necessary to construct a scheme politically to intentionally match the academic curiosity of researchers with the direction toward practical application.