This paper describes a new synthetic approach to networked polyamines based on a reductive coupling system of imines that proceeds under irradiation of visible light. The monomer used herein was a triamine synthesized by condensation of benzaldehyde and tris(2-aminoethyl)amine. As a photoredox catalyst, perylene, a simple aromatic hydrocarbon, was used. Upon irradiation of visible light using a white LED, perylene was excited and then was reduced by N,N-diisopropylethylamine added as an electron donor, and the resulting anion radical of perylene reduced the imino functions of the triamine. The reduced imino functions efficiently underwent the radical coupling to form the carbon－carbon bond, leading to the formation of the corresponding networked polymer under mild conditions.

Networked polymers were synthesized by crosslinking a polycarbosilane having acetylglucosamine-derived groups (AGA) on the side chains (polyBMSB-AGA) with hexamethylenediisocyanate (HMDI) and their chemical and physical properties were investigated. Two networked polymer films (polyBMSB-AGA-HMDI-1.0 and polyBMSB-AGA-HMDI-0.5) were prepared by adding HMDI to polyBMSB-AGA in molar ratios of [AGA] / [HMDI] = 1.0 and 0.5 respectively, and their N,N-dimethylformamide (DMF) solutions were cast on the Teflon mold followed by heating up to 120℃. Existence of urethane structures in the materials was confirmed by IR spectroscopy. Differential scanning calorimetry analysis (DSC) indicated that the crystallization of AGA groups was inhibited in the crosslinked polymer. Thermal gravimetric analysis (TGA) suggested that the networked polymers were thermally stable below 140℃. In addition, tensile strength analysis showed that the polyBMSB-AGA-HMDI-0.5 film had breaking strength of 155MPa and breaking elongation of 0.16, which indicated that the networked polymer was significantly tough material, compared to the previously reported analogous networked materials (polyBMSB-Glucose-HMDI-0.5) composed of polycarbosilane having glucose-derived groups crosslinked with HMDI.

Erasable holographic materials were fabricated using reworkable photocuring resins. The reworkable photocuring resins were prepared from a mixture of an alicyclic epoxy-containing methacrylate having a tertiary ester linkage, a multifunctional acrylate, a photoradical initiator sensitive to 532-nm light, and a photoacid generator sensitive to 365- nm light. A transmission hologram was recorded on the reworkable photocuing resins with a thickness of 100 μm by a two-beam interferometry using an Nd-YAG laser as the light source of 532 nm. The hologram recording was due to the increased refractive index caused by the crosslinking reaction of the reworkable photocuing resins by irradiation at 532 nm. The recorded hologram could be erased after irradiation at 365 nm and subsequent heating at 80 °C for 1 minute. The information of the hologram was completely disappeared by the degradation of the polymer networks in the reworkable photocuring resin due to the photoinduced acid-catalyzed decomposition of the tertiary ester linkages. The findings suggest that the reworkable photocuring resins are applicable to erasable recording materials.

There is an epoxy resin having an aromatic diketone structure as one measure for improving heat resistance of epoxy cured product. After obtaining bisphenol compound (BHBB) by Fries rearrangement reaction of diphenyl isophthalate, epoxy resin having aromatic diketone structure (BGBB) was synthesized by epoxidation reaction. As a result of evaluating the physical properties of the cured product obtained from BGBB and phenol novolac, the glass transition temperature was 159℃, which was 32℃ higher than that of bisphenol A type epoxy resin, and 13℃ higher than that of phenol aralkyl type epoxy resin. In addition, the char yield at 700℃ is 35.7 wt%, which is significantly higher than 25.9 wt% of GPAR, and the 10 wt% weight loss temperature is 410℃, which indicates a high thermal decomposition stability of the BGBB cured product.

The maleimide structure is highly reactive, exemplified by thiol-ene click reactions with thiols and Diels－Alder reactions with furans. Although post-polymerization modifications and macromolecular conjugations involving maleimide units have been widely studied, mostly due to their selectivity and high reactivity, little has been reported on the one-pot post-polymerization introduction of maleimides in polymer chains. Herein, we introduce p-maleimidophenyl isocyanate(PMPI) and its derivatives as modification agents to introduce maleimide moieties by reaction with hydroxy groups into polymer chains. The high reactivity of the resulting modification agents and of the corresponding maleimide structures once inserted in the polymer chains was examined by studying their reaction kinetics. Furthermore, the applications of the polymers functionalized by these modification agents were also introduced.