Polyglycerol, polymerized glycerol, is a highly viscous and hygroscopic liquid. It can be utilized as cosmetics, food additive, and raw material for various derivatives. We developed novel polyglycerol-based monomers which consist of polyglycerol skeleton with or without polyethylene oxide chain, and reactive end groups such as epoxy, acrylate, methacrylate, and alkoxysilane. The polyglycerol backbone and its EO adduct act as soft segments in cross-linked network.Due to their flexibility, high curing rate, and stress relaxation effect, we successfully applied these materials to the flexible coating. Moreover, our research results indicated that the hydrophilic nature of the polyglycerol-EO structure enables the moisture to be absorbed/released repeatedly. By applying these properties, we offer the wide potentials of polyglycerol-based soft materials including novel hydrogel and anti-fogging coating.

Meta-xylylenediamine (MXDA) can absorb carbon dioxide in air, and its amine carbonate salt contains no water.This MXDA carbonate salt has the advantage of eliminating the possibility of the side reactions caused by water in the use of MXDA carbonate salt as a CO₂ source. In this paper, we report epoxy foam and polyurea foam prepared by heating resins containing dispersed MXDA carbonate salt. The epoxy foam made by MXDA amine carbonate salt foaming shows storage ability of carbon dioxide in the product and high adhesiveness for iron and FRP. Use of mixed hardener of MXDA carbonate salt and free MXDA made the cell size of the epoxy foam uniform. The epoxy form consisted of closed cells as confirmed by SEM. Polyurea foam with uniform cell size could be prepared by using a mixed hardener of MXDA carbonate salt and a polymeric aromatic amine, while that with non-uniform cell size was obtained by using only MXDA carbonate salt as the hardener.

Self-repairing gels utilize reversible bonds at cross-linking points, which are repaired by the reformation of these bonds. On the other hand, such reversible bonds can be dissociated by exchange reactions with competing agents under the presence of contaminants. In this study, hydrogels with stable self-healing properties in the presence of various metal ions were prepared by using metal coordination bonds between sugars and monovalent metal ions as cross-linking points. Water-insoluble polymer complexes were formed by mixing polymers possessing a sugar side chain with poly(sodium 4-styrenesulfonate) (PSS) in water. This result indicates that the hydroxyl group of the sugar chain interacted with sodium ions, which are the counter ions of PSS. The hydrogels prepared by utilizing the complex formation exhibited self-healing ability and good stability in the presence of mono- and multivalent metal ions.

Thermosetting reaction of epoxy resin with ε-caprolactam (ε-CL) and lactide (LAC) proceeded above 170°C in the presence of DBU, yielding the cured materials quantitatively. As a model reaction of this thermosetting reaction, the reaction behavior of ring-opening copolymerization of glycidyl phenyl ether (GPE) with ε-CL and LAC was investigated using the Fineman-Ross method and the Kelen-Tüdös method. In the case of GPE and ε-CL, the monomer reactivity ratio r₁ of ε-CL and r₂ of GPE were 0.58 and 5.52, respectively. This indicated that the copolymer of GPE and ε-CL was a blocktype copolymer. In the case of GPE and LAC, the r₁ of ε-CL and r₂ of LAC were 0.85 and 1.26, respectively. This indicated that the copolymer of GPE and LAC was a gradient type copolymer. When the thermosetting reaction of epoxy resins was perfomed by adding ε-CL and LAC, the thermal stability of the cured material could be improved.

The recycling of epoxy resins and their composites has become a serious issue due to their limited degradability. In this comprehensive review, we propose an environmentally friendly recycling system for thermosetting resins that utilizes dynamic covalent disulfide bonds in the presence of a cysteine-containing tripeptide, known as glutathione. Glutathione effectively breaks down the network structure of the epoxy resin through a thiol-disulfide exchange reaction with the incorporated disulfide bonds. The resulting recycled epoxy resin retains approximately 90 % of its initial mechanical strength. Furthermore, we explore the potential applications of disulfide-including epoxy resins as reworkable adhesives and indicators of adhesion strength. By incorporating disulfide bonds into epoxy resins, we enable their efficient recycling and offer a more sustainable solution to address the growing concern of epoxy resin waste. This innovative approach promotes the circular economy and contributes to the reduction of environmental impact associated with thermoset epoxy resin disposal.