A Tokyo Institute of Technology (Tokyo Tech) research team led by Professor Takeshi Serizawa and Assistant Professor Toshiki Sawada have discovered a heat dissipating film created by assembling a nontoxic Filamentous virus. The material can be prepared simply by drying the virus aqueous solution at room temperature, and it is expected to elucidate the mechanism of new heat transport in electronics.
Since organic polymeric materials have low thermal conductivity, they are generally not suitable for rapid heat dissipations of electric and electronic equipment. To improve the thermal conductivity, it has been considered effective to heat transfer though a covalent bond by a process called “orientation processing” where molecules are aligned in the same direction, or to composite with an inorganic material.
The team at Tokyo Tech focused their efforts on forming regularly assembled structure in a wide scale from nano to macro (hierarchical assembly) that is observed in natural systems. Structures prepared in this way, where the molecules accumulate around the perimeter as an aqueous solution in which molecules are dissolved/evaporated, are utilized to assemble a filamentous virus for film preparation.
As a result, it was found that the thermal diffusivity at the edge of the film enhanced to a value comparable to that of inorganic glass, and that facilitates the utilization of the hierarchically assembled biomacromolecule. This will help in the future development of electronics composed of not old viruses, but also various naturally derived molecules.
Why? Because in the past orientation processing and composting with inorganic materials has been considered effective for high thermal conductivity or organic polymeric materials. However, since this virus film can be prepared by evaporating an aqueous solution of a filamentous virus at room temperature, materials under mild conditions do not require any special operations.
The results? The thermal diffusivity value of the outside of the firm was approximately seven times greater than those at the other points on the film, and 10 times greater than that of a non-oriented cast film. An extremely high thermal diffusivity was also observed on the outside of the film, even though the assemblies were based on the thermally-insulating non-covalent bonds.
The SAXS analysis to quantitatively characterize the orientation of phages using various phage films indicated that assemblies with highly oriented structures resulted in a high thermal diffusivity in the perpendicular direction of the filamentous phages, which may be due to a small number of structural defects. The great applicability of non-covalent bond-based assemblies will unlock novel and interesting opportunities for exploitation of next-generation thermally conductive soft materials composed of regularly assembled organic polymers such as proteins.
For more information on this project, please visit https://www.nature.com/articles/s41598-018-23102-1