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Thermal stability and flame retardancy of poly(methyl methacrylate)-clay nanocomposites

Abstract Three ammonium salts, hexadecylallyldimethyl ammonium chloride (Allyl16), hexadecylvinylbenzyldimethyl ammonium chloride (VB16) and hexadecylvinylbenzyldimethyl ammonium chloride (Bz16) were synthesized and ion exchanged onto montmorillonite. Poly(methyl methacrylate)–clay nanocomposites of all three clays were prepared by bulk polymerization and the resulting nanocomposites were characterized by X-ray diffraction and transmission electron microscopy. The clays which contain a pendant double bond are more likely to give an exfoliated material while that which contains no double bond is intercalated. The thermal stability and flame retardancy were measured by thermogravimetric analysis (TGA) and Cone Calorimetry respectively.

Surlyn®/silicate hybrid materials. I. Polymer in situ sol-gel process and structure characterization

We report the creation of a new organic/inorganic hybrid material that results from sol–gel reactions for tetraethylorthosilicate (TEOS) within poly[ethylene-co-methacrylic acid], as well as within a Zn+2 partially neutralized form of this copolymer (Surlyn®). FTIR and 29Si solid-state NMR spectroscopic probes yield information regarding molecular connectivity within the in situ grown silicate structures. FTIR analyses of Surlyn® matrix bands suggest that strong molecular level interactions between the organic and inorganic phases are not present, although there is other evidence that these phases are mechanically coupled on a larger dimensional scale. The 29Si solid-state NMR analyses indicate mainly Q3 and Q4 coordination states about the SiO4 substructures, regardless of silicate content, which is in general agreement with the interpretation of the FTIR results that show incomplete condensation. Environmental scanning electron microscopy and energy dispersive X-ray analysis results reinforce the conclusion that a significant silicate component is incorporated deep within TEOS-treated films. Differential scanning calorimetry studies of Surlyn®-Zn+2/silicate hybrids suggest that silicate incorporation essentially does not disrupt crystallinity. Thermogravimetric analyses show practically no change in the degradation onset temperature, which is consistent with organic/inorganic phase separation. The general conclusion is that a silicate phase can indeed be incorporated within this acid copolymer, as well as its Zn+2 ionomeric form, via in situ sol–gel processes.

Effect of sol-gel polymerization of tetraethylorthosilicate on internal aggregate structure in zinc-neutralized ethylene-methacrylic acid ionomers.

Sol-gel reactions of tetraethylorthosilicate have been performed in three different zinc-neutralized ethylene-methacrylic acid copolymer ionomers for the purpose of creating nanostructured organic-inorganic materials with enhanced properties. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to understand the effect of this in situ reaction on ionic aggregate morphology. EXAFS spectra showed that no large changes occurred in the aggregate structure, indicating that the internal environment of the aggregates did not nucleate the reaction, at least to the extent that the ionic domains were significantly undisrupted. However, small changes in EXAFS patterns were evident. These changes could be a result of nucleation of the reaction at the edges of the aggregates, or aggregate size rearrangement caused by the insertion of inorganic moieties into the polymer. However, the results indicate that the latter cannot include significant amounts of unaggregated zinc ions.