セルロースは地球上で最も豊富に存在する再生可能なバイオマス資源である。しかし，その低い溶解性により，応用範囲は限定されている。本研究ではセルロースの溶媒としてtetra-n-butylphosphonium hydroxide溶液（［TBP］［OH］，40％水溶液） に着目し，セルロースのエポキシ化反応，および修飾したエポキシ基の架橋によるフィルム化を検討した。［TBP］［OH］水溶液中での反応により，置換度が0.15～1.67 の間で制御されたエポキシセルロースを調整することができた。修飾したエポキシ基の重合によりセルロース鎖間が架橋されたセルロースフィルムは比較的高い透過率を示し，その弾性率は7.7 GPa であった。この値は未架橋セルロースフィルムの弾性率の1.2 倍の値を示した。

Wood is attracting attention as an environmentally friendly material in terms of carbon fixation. Therefore, wood material market is also increasing and demands are higher. Especially, surficial uses are increasing, such as car interior, cell phone casing, lump shade and so on. In its application, appearance is particularly important property because it directly affects sales. Against this background, optical transparency wood has recently attracted a lot of attention. It is generally assumed that the denser the wood, the more it absorbs light and hence the less optical transparency it tends to be. However, this could not always be explained well by the density dependence of transparency of wood. Recently, it has become clear that the diffusion on the interface internally structure of material, taking into account not only the absorption of the cell wall but also the cell structure, is important for the transparency of wood. It is shown that the light diffusion can be described by a simple Fresnel’s equation.The transmission and reflection values on the interface are determined by the relationship between the refractive indexes of the cell wall and that of the air. Using this property, the authors have developed a processing technique for the wood that transmits light only in arbitrary areas. In this review, the hierarchical structure of wood required for the development of this processing technique is described, and the insights into the design of wood gained in the course of the development of this technique are also presented.

Reaction controls of silane coupling agent （SCA） for the increase of chemisorption and the formation of self-assembled monolayer （SAM） were reviewed. When the silica particles treated with SCA are heated to accelerate the chemisorption reaction, evaporation of monomer-like SCA and the chemisorption reaction take place simultaneously. The oligomer formation in the SCA-treated layer or using the oligomer-type SCA and the SCA with long organic chain was useful restrained the evaporation and increased the chemisorption effectively. The control of amount of moisture was most important for the formation of orderly SAM. Using the chlorosilane without hydrolysis was also useful. Usually, the reaction of SCA needs hydrolysis. However, the alkoxy group in SCA can reacts with the silanol group on silica surface without hydrolysis at higher temperature. The first principles calculation is useful for the analysis of the reaction of SCA by the comparison with experimental result.

This commentary deals with progress in polycondensation along with theories. Flory formulated a theory of irreversible polycondensations, in which the formation of cyclic polymer and the change of the reactivity of polymer were not considered. Enhancement of the reactivity of AB monomer connected to the polymer end enabled to change the polymerization mechanism from step-growth to chain-growth polymerization. Enhancement of the reactivity of AA monomer connected to BB monomer made it possible to undergo unstoichiometric polycondensation. Jacobson and Stockmayer developed a theory of reversible polycondensation, in which back-biting induced the formation of low-molecular-weight cyclic polymer and ring-chain, ring-ring, and chain-chain equilibration. However, Kricheldorf found that quantitative formation of cyclic polymer through intramolecular reaction of the polymer ends, not back-biting, and that intermolecular exchange reaction of the polymer backbone took place. Accordingly, selective synthesis of linear polymer is a recent project in polycondensation. Cyclic polyesters, obtained by conventional irreversible polycondensation, were converted into linear polymers by means of reversible exchange reaction of the cyclic polymer with a small molecule having the same linkage of the polymer. Furthermore, reversible unstoichiometric polycondensation afforded selectively linear polymer capped with excess monomer at both ends. These backbone exchange reactions were applicable for adhesion.