Thermal Degradation Behavior of Polystyrene/Magadiite Nanocomposites Prepared by Surface-initiated Nitroxide-Mediated Radical Polymerization

Abstract

Exfoliated polystyrene (PS)/magadiite nanocomposites with a high suppression effect on thermal degradation were successfully prepared by in situ nitroxide-mediated radical polymerization of styrene monomer from the magadiite interlayer surface. Surface-initiated polymerization of styrene was conducted from the radical initiators immobilized on magadiite at 398 K. The number-average molecular weight (M n ) of the grafting PS increased with monomer conversion keeping a relatively low polydispersity index. The initiator efficiency was estimated to be less than 10% by size exclusion chromatography analysis. The results of X-ray diffraction and transmission electron microscopy suggested that the nanocomposites provided exfoliated structures. The fine dispersion state of magadiite in PS matrices contributed to effective suppression of the thermal degradation of PS. In addition, an interesting difference in the shape of the final residues was observed. Thermal decomposition of exfoliated PS/magadiite nanocomposites gave a substantial rigid solid as a residue, the shape of which largely depended on the concentrations of magadiite in the PS matrices. For instance, the thermal decomposition of nanocomposites produced a seamless residue that can effectively retard the decomposition rate. In contrast, the simple mixture of PS and magadiite was thermally decomposed to be powdery ash in the final residues.

Application of Organo-Magadiites for the Removal of Eosin Dye from Aqueous Solutions: Thermal Treatment and Regeneration

“…The carbon, nitrogen and hydrogen analysis was used to quantify the organic contents in organo-clays and other organo-silicates [24,32,33,34]. The elemental analysis of the organo-magadiites is summarized in Table 1.…”

Influence of magadiite dispersion states on the flammability of polystyrene and polyphenylene ether-polystyrene alloy nanocomposites

“…Figure 1 shows the chemical structure of 1-(3¢-oxa-1¢-phenyl-9¢-trichlorosilylononyloxy)-4-methoxy-2,2,6,6-tetramethylpiperadine (OMTP), which was synthesized by a previously reported method. 22 n-Dodecyltrimethylammonium chloride (DTMA) and n-octyltrichlorosilane (OTS) were bought from Tokyo Chemical Industry Co. Ltd. (Tokyo, Japan) Wakogel C-200 (particle size 75-150 mm), which was used as a starting material for magadiite, was provided by Wako Pure Chemical Industries Ltd (Osaka, Japan), Na-magadiite was prepared by hydrothermal synthesis according to the method described in literature. 25,26 Magadiite modified with DTMA (DTMA-magadiite) was prepared according to the published methods.…”

“…Two different organosilanes were immobilized onto the magadiite interlayer surface by a previously reported method. 22 DTMA-magadiite (28 g) was introduced into a 500 ml four-necked flask and dried at 373 K under reduced pressure for 3 h, then cooled to room temperature under ambient pressure. OTS (280 mmol) and OMTP (28 mmol) dissolved in 400 ml of chloroform were added to the dried DTMA-magadiite, and the mixture was stirred at room temperature under N 2 for 100 h. The solid mass was dispersed in each solution, including n-hexane, acetone and distilled water, by ultrasonication for 3 min and centrifuged twice.…”

“…22 In this study, OMTP was diluted with OTS by less than 10 mol% to be immobilized onto the magadiite interlayer surface. We exfoliated magadiite into the PS matrix by surface-initiated polymerization of styrene from the small amounts of OMTP present on the magadiite interlayer surface.…”

“…We recently immobilized an initiator for nitroxide-mediated polymerization onto the magadiite interlayer surface through the formation of covalent bonds to successfully delaminate magadiite platelets into the PS matrix by surfaceinitiated radical polymerization of styrene. 22 Unfortunately, it was found that the resultant PS/magadiite nanocomposites exhibited a significant loss of fluidity. It is therefore important to improve the flow properties of PS/magadiite nanocomposites for processing.…”