Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
See the article by Shengang Xu, Hiroto Kudo, Tadatomi Nishikubo, Shinya Nakamura and Shunichi Numata, Model reactions of calixarenes and their esterified derivatives with glycidyl phenyl ether for thermal curing reactions of epoxy resins on page 456.
At present, the lithium ion secondary battery is necessary as an energy storage device for cellular phones, notebook computers and so on. The key to even further disseminate LIB was to add a safety function to prevent thermal abuse; therefore, the separator was required to have the safety function. The Asahi Kasei Corporation has carried out the development of the safety function of the separator and succeeded in controlling the pore size of the separator for improving the performance of LIBs.
Phosphorus-containing fire retardants and inert polymers inhibit the hydrolysis of polycarbonate (PC), resulting in an increased reaction time. However, even in the presence of these materials, high yields of bisphenol-A and other phenols can be obtained from waste PC dependent on temperature. At 500 °C, polystyrene is also pyrolyzed.
We report the direct synthesis of new functional novolacs having allyl ether in the side chain by the addition-condensation of allyl phenyl ether (1). In polymerization of 1 with formaldehyde using hydrated sulfuric acid as a catalyst, Claisen condensation did not occur with the polymerization; therefore, pure allylated novolac (4) without a phenol moiety was obtained. The obtained polymer (4) can be applicable for a latent curing system.
A series of cyclic acetals were investigated with regard to their abilities to function as coinitiators in free-radical photopolymerization induced by camphorquinone (CQ). It was found that the polymerization efficiency of the coinitiators did not follow the efficiency of photoinduced formation of the initiating radicals.
Model reactions of calix[4]resorcinarene (CRA), p-tert-butylcalix[n]arene (BCA[n], n=4, 6, 8) and their esterified derivatives with glycidyl phenyl ether (GPE) were examined using tetraphenylphosphonium chloride (TPPC) as the catalyst in chlorobenzene at 120 °C for 6 h. It was found that the degree of introduction of GPE (D.I.) to CRA series was higher than 95%, whereas for BCA[n] (n=4, 6, 8) series, D.I.s were lower than 81%. Therefore, CRA and its derivatives are good potential curing agents for preparing cured epoxy resins with excellent thermal properties.
We succeeded in elongational crystallization of isotactic polypropylene (iPP) by compressing the supercooled melt. When the elongational strain rate () surpassed a critical value (*=2×102 s−1), crystallization behavior and structure discontinuously changed. The induction time decreased by 10−6 times (Figure), the crystal size decreased by 10−3 times and morphology changed from spherulites to ‘nano-oriented crystals (NOCs)’. It is concluded that large induced the ‘oriented melt’ and NOCs. The NOCs showed high crystallinity and ultra-high performances, such as high tensile stress (210 MPa).
Birefringence and tensile stress of vulcanized natural rubber samples were measured simultaneously. The effect of finite chain extensibility could be clearly detected. The increase in birefringence was related to the degree of orientation of amorphous chains to be incorporated into crystals. The normalized stress decreased in a manner that is almost independent of network-chain density. These experimental results could be successfully explained by assuming a certain fraction of network chains that behave in a manner similar to that of a fluid.
N-Acyl-3-aminopropyl silica gel fillers (1) are developed to reduce the interfacial adhesion energy (W) between fillers and polystyrene (PS). The effects of alkyl chains on the W interface force have been evaluated by surface tension of 1 and PS. Moreover, the adhesion of 1 toward PS was evaluated by glass transition temperature measured by DSC.
Two kinds of fluorinated co-oligomeric nanoparticles, RF-(IEM)x-(Ad-HAc)y-RF and RF-(AMPS)x-(Ad-HAc)y-RF, enabled a selective morphological control, which is divided into inclusion type and adsorption type, respectively, for the encapsulation of magnetic nanoparticles into each fluorinated particle core. More interestingly, RF-(AMPS)x-(Ad-HAc)y-RF co-oligomeric nanoparticles can decrease the LCST effectively in organic media such as t-butyl alcohol through the encapsulation of magnetic nanoparticles into these particle cores.
Effects of crosslinked nanoshells covering self-oscillating microgels on their oscillating behaviors were reported. We carried out seeded precipitation polymerization of N-substituted acrylamide derivatives using preformed, self-oscillating microgels as cores. The obtained core/shell microgels were characterized by dynamic light scattering. Thereafter, their oscillating behaviors were characterized by changes in optical transmittance. In this study, oscillating behaviors of core/shell microgels were compared with that of the parent core microgel to clarify the effect of nanoshell addition on the oscillating behaviors of microgels.
Porous rods of poly(tetrafluoroethylene) (PTFE) were fabricated by molding PTFE powder and fumaric acid (FA) at room temperature, and sintering at 400 °C. The microstructures of the molding mixtures were observed with a scanning electron microscope (SEM). High-resolution images of SEM revealed that the fibrous structure heated at 310 °C is composed of small particles of PTFE connected with fibrils, and these particles were sintered into grains after heating at 400 °C. Pore size could be controlled by changing the volume fraction of FA.
Effects of processing parameters, such as applied voltage, feed rate, viscosity of polymer solution, salt as additive and humidity in electrospinning, on morphologies such as diameter and uniformity of nanofibers were investigated, and preparation of bead-free ultrafine uniform nanofibers was carried out. Nanofibers fabricated from fluorinated polyimide indicated an ultrafine uniform diameter and, finally, we succeeded in preparing a uniform nonbeaded nanofiber with a diameter of less than 40 nm.
A new approach, vapor-phase-assisted surface photopolymerization (photo-VASP), was investigated to control the chemical and physical properties of complicated and delicate cellulose fabric surfaces. In this approach, a gaseous initiator was adsorbed on cellulose fibers, followed by photo-VASP of a fluoromonomer, 2,2,3,3,3-pentafluoropropylmethacrylate, under ultraviolet irradiation. Photo-VASP proceeded smoothly on the cellulose fiber surfaces to result in a thin coating showing a superior hydrophobic property.
