Naturally occurring spider silks are known to possess a remarkable mechanical strength, where oligo-alanine sequences and glycine-rich sequence plays important roles as hard segment associated by hydrogen bonding, and flexible soft segment, respectively. We describe the facile preparation of multi-block copolymer, composed of oligo(L-alanine) segment, acting as an effective hard segment by intermolecular hydrogen bonding (physical cross-linking), and the poly(butadiene) of soft segment, respectively, by two step reaction (chain-growth polycondensation of Nα－phenoxycarbonyl derivative of alanine along with the elimination of phenol and CO₂ and subsequent treatment with hexamethylene diisocyanate. These multi-block copolymers formed a flexible and transparent films and their mechanical properties are investigated. The modulus and tensile strength becomes higher as increasing the degree of polymerization of oligo(L-alanine), on the other hand, the elongation at break decreased significantly with increasing it. In addition, the increasing the length of poly(butadiene) as well as the utilization of racemic alanine in the hard segment were effective way to reduce the modulus, suggesting the possible tuning of mechanical properties (tensile strength: 4.7－9.8MPa, elongation at break: 200－500%).

Cresol formaldehyde novolac resins (Cre/Form) are used as photo-resist materials because they can be applied minutely onto hard silicon wafers, which are used in the process of making integrated semiconductor circuits. Resins with high hardness cannot be applied minutely onto flexible bases, such as polyimide films. To develop novolac resins for photo-resists having flexibility beyond that of Cre/Glu novolac resin using glutaraldehyde (Glu) as a crosslinking agent,5-hydroxymethylfurfural (HMF) derived from fructose (Fru) one of a monosaccharide was used as a crosslinking agent.Synthesis of m-cresol 5-hydroxymethylfurfural novolac resins (m-Cre/HMF) was carried out in a stepwise reaction of m-Cre and HMF obtained at the first step. The obtained m-Cre/HMF novolac resin had M_w from 1200 to 2900, and the dissolving rate for alkaline aq. solution (DR) decreased with increasing M_w. To prepare cast films, resins meeting the condition of DR below 500Å/s were chosen. Cast films of thickness 5 μm onto the polyimides were prepared by spin-coating, heatsetting and then exposing to developer solution. The flexibility of the obtained resins was evaluated by observation with a microscope for their bent parts. The m-Cre/HMF novolac resin showed higher flexibility than that of Cre/Glu novolac resin. The lithography performance of the m-Cre/HMF novolac resin coated onto the silicon wafers in 1.5 μm thickness was examined. The residual membrane thickness was high (99%) and the resist pattern could be drawn up in 5 μm width clearly.

Phenolic resin modified with lignocellulose nanofiber (LCNF) was developed utilizing pulverized wood flour. Subsequently, application of the LCNF modifiedphenolic resin to brake friction materials was examined. It was shown that flexural strength of the friction materials was improved by using the LCNF modified phenolic resin as a binding material. Stick－slip phenomenon is known as cause of brake noise or vibration and is evaluated by amplitude of friction coefficient (Δμ). Measurement of Δμ showed that the LCNF modified phenolic resin decreased Δμ compared with that of unmodified phenolic resin. Also, it was found that Δμ depended on the LCNF content of resin, and 3 mass% LCNF showed the lowest Δμ.

Epoxy resins are used in the fields of paints, adhesives, composites and electronics. Epoxy resins are composed of multifunctional epoxy compounds, curing agents, diluents, modifiers, and fillers. Many multifunctional epoxy compounds have high viscosity. Therefore, a diluent is an essential raw material in the design of epoxy resin. Low viscosity liquid epoxy compounds at room temperature tend to be packaged with reactive diluents. In particular, mono epoxides tend to focus only on their ability to reduce viscosity, and tend to be overlooked as a modifier. We studied the influence of the molecular structure of the reactive diluent on the thermal and mechanical properties of bisphenol A type epoxy resin. It has been found that the aromatic mono epoxide has the effect of toughening epoxy resins. In this paper, we explain the types, preparation methods, and functions of glycidyl types reactive diluents.

Cyanate ester polymer has been put to practical use as heat-set resin in some fields. Especially BT resin, blend of cyanate ester resin and bismaleimide, bearing improved moisture absorption has a superior characteristic for a high frequency use. The homopolymer of the cyanate ester has high T_g about 300℃, but high cure temperature, high heat of polymerization and brittleness are unsolved problems. However, the fault is made up by modification with other monomers and the filler addition. Improvement of the operating temperature of the power electronics inverter devices gives new development target of the encapsulate and thermally-conductive seat. In addition to epoxy, benzoxazine, maleimide and cyanate ester are expected in the range of T_g ≥ 200℃. An application of cyanate ester toward the next generation is expected because of high T_g at low cure temperature.