筒場 豊和

Incorporation of rotaxane scaffolds into the crosslinking points of polymer networks significantly affects their rheological and mechanical properties. The present study involves the synthesis of a new rotaxane-type crosslinker containing nitrile N-oxide functional groups on both the axle and wheel components. The prepared crosslinker is highly reactive; however, it can be isolated and applied in the crosslinking reaction of a commercially important polymer, namely ethylene-propylene-butadiene monomer rubber (EPDM), in the absence of additives and catalysts. Tensile tests reveal that compared to a network containing conventional crosslinking points, both breaking strength and strain of the network structure prepared herein are improved due to the incorporation of movable crosslinking points. The synthesized network structure also exhibits five times higher fracture energy. The developed post-crosslinking methodology for the direct introduction of movable crosslinking points into pre-formed polymers will be valuable in the production of rotaxane materials for various applications.

<p>Polyesters that have a nitrile <italic>N</italic>-oxide function at the initiation end were prepared and applied to a catalyst-free click reaction for star polymer synthesis.</p>

<p>A new synthetic route for obtaining polyfunctional nitrile <italic>N</italic>-oxides from OH-tethering nitrile <italic>N</italic>-oxide is reported.</p>

The polymer nitrile N-oxide containing poly(ethylene glycol) (PEG) skeleton PEG-CNO was synthesized via a stepwise reaction. The catalyst-free click reaction of PEG-CNO with terminal CvC bond-tethering compounds afforded the corresponding diblock and multi-arm star polymers in high yields. The click reactions under solvent-free conditions resulted in significant rate acceleration and high yields of the polymers.

Mono-, di-, and trifunctional kinetically stabilized aliphatic nitrile N-oxides were synthesized via a two-step process comprising an initial nucleophilic addition of a heteroatomtethering and a carbon-centered nucleophile to a nitroethene and subsequent dehydration of the resultant nitroalkane. We further present the first X-ray crystal structure investigation of an aliphatic nitrile N-oxide. The kinetics of the products' click reactions and DFT calculations confirmed that the obtained nitrile N-oxides had high reactivities.

It has been achieved to obtain flexible self-supporting supramolecular polymeric membranes consisting of only 1,3,5-trisubstituted benzene derivatives prepared by highly selective photocyclic aromatization of the corresponding poly (substituted phenylacetylene)s having a columnar structure. The flexibilities of the self-supporting supramolecular polymeric membranes were enhanced by introducing hydroxyl groups or phenylene groups to the starting polymers (monomers). There were two reasons for the enhanced strength: 1) introduction of intercolumnar hydrogen bonds and 2) enhancement of the degree of intracolumnar stackings. This strength depended on the structure of the starting polymers which functioned as a template. (c) 2013 Elsevier Ltd. All rights reserved.

By using a new achiral phenylacetylene having bulky substituents as a monomer, living-like helix-sense-selective polymerization (HSSP) has been achieved. This is the first example of the HSSP of substituted acetylenes where the degree of polymerization was controlled. The resulting one-handed helical living polymer initiated polymerization of a second monomer to successfully yield a block copolymer. (C) 2013 Elsevier Ltd. All rights reserved.