A novel resin, poly(dimethylsilylene-ethynylene-phenoxyphenoxyphenylene-ethynylene), was synthesized from 1,4-bis( p-ethynylphenoxy)benzene and dimethyldichlorosilane through Grignard reaction. The structures of the monomer and the resin were characterized by elemental analysis, Fourier transform infrared, proton nuclear magnetic resonance, electron ionization-mass spectrometry and gel permeation chromatography. The thermal behaviour of the resin was examined by differential scanning calorimetry. The cured resin exhibits excellent dielectric property, high glass transition temperature, good mechanical properties and high thermal stability. The flexural strength and impact strength of the cured resin were 55.0 MPa and 10.5 KJ m−2, respectively. The degradation temperature at 5% weight loss of the cured resin arrived at 549°C in nitrogen.
In this study, photoisomerizable polyacrylate containing spiropyran moieties was synthesized. By taking advantage of the photoinduced structural transformations of the spiropyran moieties, photoinduced microscopic ordering and eventually macroscopic patterns were formed in the polymer films consisting of spiropyran-containing polyacrylate (SPPA) and tetraoctylammonium bromide (TOAB). The patterns thus obtained are composed of concentric rings, which alternatively consist of macroscopic convex ridges and concave valleys, with the former being amphormous phases and the latter being ordered mesomorphous ones. It was found that the open-ring protonated merocyanine (MC) form of the spiropyran moieties, which is triggered by UV illumination, was crucial to the formation of mesomorphous structure and macroscopic patterns for this polymer−surfactant system. It is possible that the interaction between the MC form and TOAB leads to the formation of the microscopic ordering and macroscopic pattern in the polymer−TOAB films. This photoinduced macroscopic patterning in solid polymer−surfactant system could offer a new way for modulating and/or fabricating ordered supramolecular structure in macroscopic dimension by using light as a trigger.
Si‐B‐C ceramics with different elemental compositions and microstructures were prepared by the pyrolysis of an o‐carborane‐containing poly(silylene‐arylacetylene) (CB‐PSA) thermoset at 1000°C, 1200°C, 1300°C, and 1450°C. The thermo‐oxidative stability of the ceramics was investigated by tracing the weight loss of ceramics during the isothermal oxidation at 800°C, 1000°C, and 1200°C under dry oxygen. The chemical bonding states of the ceramics before oxidation and the elemental compositions of the ceramics after oxidation were analyzed by X‐ray photoelectron spectroscopy (XPS). The surface morphologies of the ceramics after oxidation were recorded using scanning electron microscopy (SEM). The results show that the Si‐B‐C ceramic prepared at 1450°C produces an integral borosilicate film on the surface of the ceramics when oxidized at both 1000°C and 1200°C and exhibits better oxidation resistance than the other Si‐B‐C ceramics prepared at 1000°C, 1200°C, and 1300°C. Oxidation temperatures, elemental compositions, and crystallites of the Si‐B‐C ceramics are found to influence the formation of the borosilicate films which plays an important role in the thermo‐oxidative stability of the ceramics.
Polymer composites with carbon-based nano-fillers have generated significant interest in industry and science because of their multifunctional and valuable properties. An APA-functionalized GO nanofiller (GO-APA) was prepared through the reaction between graphene oxide (GO) and 3-aminophenyl acetylene (APA) in dimethylformide (DMF) with ammonia hydroxide. Furthermore the PDSEPE/GO-APA composites were made from Poly(dimethysilyleneethynylenephenylene ethynylene) (PDSEPE) and GO-APA. FT-IR, XRD, XPS, SEM, DSC and TGA techniques were used to characterize the chemical compositions and physical and chemical properties of GO-APA and PDSEPE/GO-APA composites. As a result, the prepared PDSEPE/GO-APA composites show high thermal stabilities, excellent electrical conductivity and good flexural strength. When the weight percentage of GO-APA reaches 0.5%, the PDSEPE/GO-APA composite electrical conductivity increases by 6 orders of magnitude and the flexural strength improves by nearly 33% compared with that of cured PDSEPE resin.
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