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Polyrotaxane (PRx) has a necklace-like structure, which exhibits many features (e.g., cyclic molecule slippage) that are not found in other supramolecular structures. In this review, we report that the number of cyclic molecules, the length (molecular weight) of the linear molecules, and the combination of the cyclic molecules and linear molecules in PRx can be precisely controlled to maximize cyclic molecule slippage. In addition, we created a material that quickly recovers its material strength because of the cyclic molecule slippage of PRx.
The role of alcohol in the Yb(OTf)3- and Y(OTf)3-catalyzed stereoselective radical polymerization of acrylamides is clarified. The coordination of two equivalents of alcohol to the metal triflate generates a complex, which increases both the polymerization rate and stereocontrol compared to those without an alcohol. The importance of hydroxyl groups of the alcohol is suggested by the observed secondary isotope effect for the rate enhancement. The conditions are highly compatible with those for organotellurium-mediated radical polymerization, and the dual control of molecular weight and tacticity is successfully achieved.
Poly(methacrylated vanillin) (PMV) was investigated for its reactivity in multicomponent reactions as a reactive polymer that can be sourced from lignin-based components. The Passerini three-component reaction (Passerini-3CR) of the PMV in solution phases revealed that the PMV pendant aldehydes can be converted into the corresponding α-acyloxy amides with >90% conversions under the optimized conditions. Taking advantage of this high reactivity of PMV in solution phase, its immobilized cellulose fabric (Cell-g-PMV), a wood biomass-sourced organic hybrid, was subjected to the Passerini-3CR, enabling an engraftment of carboxylic acid and isocyanide components on the cellulose-based fabrics.
Isotactic poly(N,N-diethyl acrylamide) (i-PDEAA) was prepared by ytterbium triflate/H2O-catalyzed radical polymerization in the presence of an organotellurium chain transfer agent. i-PDEAA single crystals were successfully grown from solution using a mixture of methanol and diethyl ether as the solvent. Selected-area electron diffraction patterns obtained by transmission electron microscopy provided clear information about the unit cell and suggested polymorphisms of the i-PDEAA crystals. Lattice constants of the two crystal forms were reported.
In this study, high birefringent acetylene group containing azobenzene-based polymers were synthesized as materials for rewritable green-laser holograms, and their properties were evaluated. Birefringence change of polymer, which has an absorption wavelength suitable for green laser (532 nm), is 0.018. The diffraction efficiency of polymer was 72% under low-energy irradiation (7 J/cm2). These results show that the hologram recording material made in this study with high birefringent azobenzene are stable, without undergoing decomposition even when repeated recording and rewriting were performed.
A facile modification method for a commercial polyethylene membrane separator using a cross-linked single-ion conducting polymer network with a highly delocalized anionic group was developed. A cross-linker, poly(ethylene glycol) diacrylate, and a delocalized anionic monomer, lithium (4-styrenesulfonyl)(trifluoromethanesulfonyl)imide, were used to modify the surface of the polyethylene separator via UV-initiated polymerization. The resulting polymer coating improves the electrolyte wettability and suppresses the diffusion of anionic species across the separator. The effect of the polymer modification of the separator on the electrochemical properties of nonaqueous Li-O2 cells was investigated.
The salt addition affects the structure and properties of poly(vinyl alcohol) films as it reduces the hydrogen bonding in PVA chains and decreases the crystallinity. Consequently, the Tg shifts to low temperatures, and the modulus beyond Tg decreases markedly. This study confirmed that the impact of bromine salts on the structure and properties followed the order of Hofmeister series, i.e., Li+ > Na+ > K+. Although cations play an important role, the data obtained also demonstrated that the strong ion–dipole interactions between anions and PVA chains have a significant impact on the crystallinity and Tg.
A dinuclear Pd(II) complex possessing a cyclic ligand was applied as a coordinative cross-linker of acrylonitrile–butadiene rubber (NBR). Tensile tests revealed that the mechanical properties of the coordinatively cross-linked NBRs were improved compared with those of the original NBR. Increasing the loading amount of the complex enhanced Young’s modulus, tensile strength, tensile strain, and toughness. The cross-linked NBR could be reused with a simple dissolution and drying process, which featured coordinative cross-linking.
We report a novel approach of siloxane bond splitting in organosiloxane using mixture of tris(pentafluorophenyl)borane and dimethyl carbonate. In the first part of this note, depolymerization of polydimethylsiloxane by dimethyl carbonate and with the addition of tris(pentafluorophenyl)borane is studied. Reactions are studied at different concentrations of above-mentioned reagents and temperature while the second part of this note represents theoretical calculation results which explain the mechanism of the depolymerization reaction.
