Yoshifumi Amamoto

Self-healing of covalently cross-linked polymers under an ambient visible light in the bulk state, in air, at room temperature using radical exchange of thiuram disulfide units is reported. The successful attachment of surfaces of cut pieces proceeded under ambient conditions under exposure to visible light from a commercial tabletop lamp, as confirmed by bending and tensile tests.

Well-healed: Polymers cross-linked with trithiocarbonate (TTC) units were prepared by a RAFT polymerization. The repeatable self-healing systems or macroscopic fusions were accomplished by UV irradiation of the cross-linked polymer in solution and in the bulk state. The macroscopic fusion of completely separated parts was successful (see pictures, BA=n-butyl acrylate).

Gut geheilt: Mit Trithiocarbonat(TTC)-Einheiten vernetzte Polymere wurden durch RAFT-Polymerisation hergestellt. Die selbstheilenden Systeme oder makroskopischen Zusammenschlüsse entstanden bei UV-Bestrahlung des vernetzten Polymers in Lösung und im Festkörper. Es gelang sogar der Zusammenschluss vollständig getrennter Teile (siehe Bilder, BA=n-Butylacrylat).

Programmed thermodynamic formation of star-like nanogels from designed diblock copolymers with thermally exchangeable dynamic covalent bonds in their side chains and structure analysis of the nanogels were performed. Linear diblock copolymers that consist of poly(methyl methacrylate) block and random copolymer block of methyl methacrylate (MMA) and methacrylic esters with alkoxyamine moiety were prepared by atom transfer radical polymerization (ATRP). By heating the diblock copolymers in anisole

Changes in the structure of networks of chemical gels cross-linked by covalent bonds have been investigated using reshuffling (i.e., degenerative exchange) reactions of the covalent bonds. These reactions can be applied to form functional materials including self-healing polymers, plasticity in cross-linked polymers, and shape-memory polymers. Herein, network structures of chemical gels were changed through radical reshuffling reactions of trithiocarbonate (TTC) units, and swelling degrees or ne

Posttranslational modifications (PTMs) of histones play an important role in the complex regulatory mechanisms governing gene transcription, and their dysregulation can cause diseases such as cancer. The lack of methods for site-selectively modifying native chromatin, however, limits our understanding of the functional roles of a specific histone PTM, not as a single mark, but in the intertwined PTM network. Here, we report a synthetic catalyst DMAP-SH (DSH), which activates chemically stable th

Covalently networked polymer gels were developed with two notable functionalities: de-cross-linking by dynamic covalent exchange based on a radical crossover reaction and insertion of a monomer into the cross-linkers. The network polymer gels were synthesized by free-radical copolymerization of styrene and a bifunctional monomer with an alkoxyamine linker that has two capabilities to exchange with other alkoxyamine derivatives in the radical process and to polymerize styrene in a controlled mann

The formation of symmetrical and asymmetrical (miktoarm) star-like nanogels by the cross-linking reaction of complementarily reactive diblock copolymers via a radical crossover reaction of alkoxyamine units was successfully accomplished. Four types of diblock copolymers with alkoxyamine units connected at different positions and different chemical compositions were prepared by random copolymerization of methyl methacrylate and methacrylic esters with alkoxyamine from poly(methyl methacrylate) or

The formation of star-like nanogels with different arm lengths via a radical crossover reaction of alkoxyamine units in diblock copolymers and direct observation of the star-like nanogels by scanning force microscopy were successfully accomplished.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSolvent-Controlled Formation of Star-like Nanogels via Dynamic Covalent Exchange of PSt-b-PMMA Diblock Copolymers with Alkoxyamine Units in the Side ChainYoshifumi Amamoto†, Moriya Kikuchi‡, Hideyuki Otsuka*†‡, and Atsushi Takahara*†‡View Author Information† Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan‡ Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka

Mesh-size control of network structures of chemical gels, i.e. mesh expansion by insertion of styrene derivatives and mesh shrinking by insertion of divinylbenzene in the gels, was carried out. Chemical gels with alkoxyamine at their cross-linking points were synthesized by radical copolymerization of methyl methacrylate and divinyl monomer with alkoxyamine units. The monomers were inserted by heating the gels with each monomer separately, and the network size was evaluated by small-angle X-ray

Abstract By heating two types of diblock copolymers with complementarily reactive alkoxyamine units in the side chains, nanogels were formed as a result of a radical crossover reaction of the alkoxyamine units. The transformation from the diblock copolymers to nanogels and their absolute molecular weight were obviously dependent on reaction concentrations and the mixing ratio of two types of diblock copolymers.

The complicated structure-property relationships of materials have recently been described using a methodology of data science that is recognized as the fourth paradigm in materials science. In network polymers or elastomers, the manner of connection of the polymer chains among the crosslinking points has a significant effect on the material properties. In this study, we quantitatively evaluate the structural heterogeneity of elastomers at the mesoscopic scale based on complex network, one of th