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In this paper, we have prepared shape memory reduced graphene oxide-vitrimer composites via in situ reduction of graphene oxide (GO) during the curing reaction. Because of good compatibility between GO and epoxy resin, reduced graphene oxide (rGO) has a good dispersion in the epoxy matrix. Conventional thermoset shape memory polymers can only maintain one permanent shape, while these obtained composites can be randomly reconfigured into other shapes via dynamic covalent transesterification reaction at 200 °C above transesterification temperature (TV). They can recover quickly from fixed shapes to their initial shapes with shape fixity ratio higher than 95% and shape recovery ratio higher than 97%. Besides, the rGO-vitrimers show good mechanical properties and thermal stabilities. In addition, sequent near-infrared (NIR) irradiation can control the shape recovery, because rGO can serve as an energy convertor to convert NIR irradiation into thermal energy. [ABSTRACT FROM AUTHOR]

The designed polyurethane surfactant (PUS) was used as a macromolecular surfactant for the preparation of polyacrylate emulsion without any other surfactants and stabilizers. The resultant polymer emulsion and film properties were compared with those of the emulsion prepared with sodium dodecyl sulfate (SDS). Long shelf-life of the polymer emulsion can be achieved at proper composition. Polymer particles show core-shell and nano-scale structure with narrow distribution. Thermoanalysis results show phase separation in the polymer film, which leads to gloss decrease with the PUS content increase. Such polymer films show good water resistance and mechanical strength. [ABSTRACT FROM AUTHOR]

The objective of this study is using 2,4,6-trimethylolphenate (TMP) as modifier to prepare stable TMP-Urea-Formaldehyde resins (TMPUF) with low formaldehyde emission and using TMPUF to improve mechanical properties and water resistance of the common filter paper. The prepared TMPUF was characterized by IR, DSC and POM. The results indicated that as the mass ratio of TMP/U was increased, the free formaldehyde concentration of the TMP modified UF resins was decreased. Curing temperature of TMPUF was increasing with the decreasing of free low formaldehyde and POM analysis showed that the crystalline structure of TMPUF is destroyed with the adding of TMP. In addition, mechanical properties, thermal stability and water absorption of TMUF impregnated papers have been studied. The results showed that both mechanical properties and water absorption of TMPUF impregnated papers can be improved in the experimental range. However, all TMPUF impregnated paper shows little difference in thermal stability. These results indicated that TMP as a kind of phenol-formaldehyde intermediate is a useful alternative to formaldehyde and phenol to reduce environmental pollution. This work provides a method of preparing stable TMPUF adhesives with low formaldehyde emission used for wood adhesives and paper impregnating applications. [ABSTRACT FROM AUTHOR]

Modified micro-emulsion polymerization was successfully used to synthesize a kind of ambient temperature self-crosslinking core-shell emulsion, consisting of polyacrylate core and vinyltriethoxysilane (VTES) modified polyacrylate shell, by varying the ratio of soft monomer (BA) and hard monomer (MMA) which is different in the core and shell. The emulsion and its film formed at ambient temperature were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Core-shell structure was clearly shown in TEM micrographs, and two distinct glass transition temperatures ( T) were confirmed by DSC analysis. Lower T of core phase analyzed by DSC and self-crosslinking properties of VTES characterized by crosslinking degree cause latex particles form continuous film at ambient temperature. Thermal and mechanical properties and the surface properties of the latex films were also investigated. Results showed that the core-shell latex films containing 5 and 7.5 % VTES exhibited higher thermal stability, better mechanical properties, higher contact angle, and water resistance compared with pure polyacrylate film. [ABSTRACT FROM AUTHOR]

novel bipolar copolymer combining hole-transporting units, electron-transporting units and light-emitting units (Alq) had been synthesized via free radical copolymerization of N-vinylcarbazole and Alq monomer containing phenothiazine group. The chemical structure and composition of the copolymer were characterized by H NMR, C NMR, FT-IR spectroscopy, and elemental analysis as well as gel permeation chromatography (GPC). The number-average molecular weight ( M) and polydispersity of these copolymers with different Alq contents were around 20000 and 1.4, respectively. The DSC and TGA measurements indicated that the copolymer has excellent thermal stability and high glass transition temperatures ( T). The optical properties of the copolymer in solution and solid state were investigated by UV-vis and photoluminescence (PL) spectra. Additionally, the effects of Alq content, concentration, excitation wavelength and solvent on PL spectra were studied and the results indicated that there exists efficient energy transfer in the process of photoluminescence. The introduction of carbazole and phenothiazine, as hole-transporting groups and energy transfer stages, provides an effective way to improve carries transporting property and energy transfer efficiency, consequently improving luminescence properties of Alq-based copolymer. [ABSTRACT FROM AUTHOR]