PMMA–mesocellular foam silica nanocomposites prepared through batch emulsion polymerization and compression molding

Bio-Based Polymer Developments from Tall Oil Fatty Acids by Exploiting Michael Addition

In this study, previously developed acetoacetates of two tall-oil-based and two commercial polyols were used to obtain polymers by the Michael reaction. The development of polymer formulations with varying cross-link density was enabled by different bio-based monomers in combination with different acrylates—bisphenol A ethoxylate diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate. New polymer materials are based on the same polyols that are suitable for polyurethanes. The new polymers have qualities comparable to polyurethanes and are obtained without the drawbacks that come with polyurethane extractions, such as the use of hazardous isocyanates or reactions under harsh conditions in the case of non-isocyanate polyurethanes. Dynamic mechanical analysis, differential scanning calorimetry, thermal gravimetric analysis, and universal strength testing equipment were used to investigate the physical and thermal characteristics of the created polymers. Polymers with a wide range of thermal and mechanical properties were obtained (glass transition temperature from 21 to 63 °C; tensile modulus (Young’s) from 8 MPa to 2710 MPa and tensile strength from 4 to 52 MPa). The synthesized polymers are thermally stable up to 300 °C. The suggested method may be used to make two-component polymer foams, coatings, resins, and composite matrices.

Bioinspired growth of iron derivatives on mesoporous silica: effect on thermal degradation and fire behavior of polystyrene

Aiming to investigate the influence of pore property of mesoporous material on thermal degradation and fire behavior of polystyrene (PS), the ultrafine iron derivatives were uniformly grown on the interior wall of SBA-15 via the coordination-induced assembly by bioinspired polydopamine (PDA). The resultant SBA-15@PDA@Fe was verified by various characterizations with the dominant component of FeOOH. Compared with PS composites with SBA-15, PS composites with SBA-15@PDA@Fe revealed the notably divergent alteration in thermal and thermal-oxidation degradation behavior, which was determined by the changed pore property. The iron derivatives in SBA-15 mesopores possessed the stronger affinity to aerobic volatiles than anaerobic volatiles (via π-π coordination), which inhibited the release of oxidatively decomposed products and enhanced thermal-oxidation stability. In addition, SBA-15@PDA@Fe was capable to preferentially improve limiting oxygen index, accompanied by the decrease of smoke production through suppressing smoke precursors. The glass transition temperature (T _g) of PS/SBA-15 was slightly increased via the bioinspired modification.

Facile fabrication of mesostructured natural rubber/silica nanocomposites with enhanced thermal stability and hydrophobicity

Natural rubber (NR)/hexagonal mesoporous silica (HMS) nanocomposites (NRHMS) with enhanced thermal and hydrophobic properties were facilely prepared via in situ sol-gel formation with pH adjustment using a low sulphuric acid (H2SO4) acid concentration. The effect of the amount of 0.5 M H2SO4 (2.5-10 g) added into the pre-synthesis mixture on the physicochemical properties of the obtained NRHMS nanocomposites was investigated. With a small addition of H2SO4 solution, the fabricated NRHMS nanocomposite possessed an improved wormhole-like mesostructure arrangement with a thicker silica wall, which retarded the thermal decomposition of the NR phase, as deduced from the auto-oxidation of NR by thermogravimetric analysis. The H2O adsorption-desorption measurement revealed an increased hydrophobicity of the NRHMS composites, explained by the acid-catalyzed bridging of free silanol groups to siloxane bonds, which was supported by the X-ray photoelectron spectroscopy analysis. Scanning transmission electron microscopy with energy dispersive X-ray spectroscopy elemental mapping revealed a good dispersion of the NR phase within the mesostructured silica. However, a high amount of added H2SO4 solution led to silica-NR phase separation due to the decreased hydrophobic interaction between the silica precursor and rubber chain, as well as an agglomeration of the NR phase itself. The mechanism of NRHMS nanocomposite formation under pH-controlled conditions was proposed to proceed via a cooperative self-assembly route.

The preparation of modified boehmite/PMMA nanocomposites by in situ polymerization and the assessment of their capability for Cu2+ ion removal

The addition of nanoboehmite as a nanofiller into the polymer matrix led to the improvement of the thermal properties and increased the active sites of nanocomposites for Cu(ii) removal.

Thin film nanocomposite embedded with polymethyl methacrylate modified multi-walled carbon nanotubes for CO2 removal

Thin film nanocomposite loaded with milled polymethyl methacrylate grafted multi-walled carbon nanotubes achieved 29%, 47% and 9% increment in CO₂ permeance, CO₂/N₂ and CO₂/CH₄ selectivity respectively compared to its thin film composite counterpart.

Effects of surface activation on the structural and catalytic properties of ruthenium nanoparticles supported on mesoporous silica

Using colloid-based methods to prepare supported catalytic metallic nanoparticles (NPs) often faces the challenge of removing the stabilizer used during synthesis and activating the catalyst without modifying the particles or the support. We explored three surface activation protocols (thermal oxidation at 150 °C, thermal reduction at 350 °C, and argon-protected calcination at 650 °C) to activate ruthenium NPs supported on mesoporous silica (MSU-F), and assessed their effects on the structural and catalytic properties of the catalysts, and their activity by the aqueous phase hydrogenation of pyruvic acid. The NPs were synthesized by polyol reduction using poly-N-vinyl-2-pyrrolidone (PVP) as a stabilizer, and supported on MSU-F by sonication-assisted deposition. The NPs maintained their original morphology on the support during activation. Ar-protected calcination was the most efficient of the three for completely removing PVP from particle surfaces, and provided the highest degree of particle crystallinity and a metal dispersion comparable to commercial Ru/SiO2. Its catalytic performance was significantly higher than the other two protocols, although all three thermally activated catalysts achieved higher activity than the commercial catalyst at the same Ru loading. Post-reaction analysis also showed that the supported catalyst activated at 650 °C retained its morphology during the reaction, which is an important requirement for recyclability.

Synthesis of Polymer-Mesoporous Silica Nanocomposites

Polymer nanocomposites show unique properties combining the advantages of the inorganic nanofillers and the organic polymers. The mesoporous silica nanofillers have received much attention due to their ordered structure, high surface area and ease for functionalization of the nanopores. To accommodate macromolecules, the nanopores lead to unusually intimate interactions between the polymer and the inorganic phase, and some unusual properties can be observed, when compared with nonporous fillers. Whereas many review articles have been devoted to polymer/nonporous nanofiller nanocomposites, few review articles focus on polymer/mesoporous silica nanocomposites. This review summarizes the recent development in the methods for synthesizing polymer/mesoporous silica nanocomposites based on the papers published from 1998 to 2009, and some unique properties of these composites are also described.