Composites of Kaolin and Polydimethylsiloxane

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• 作者：Yan Zhang ; David I. Gittins ; David Skuse ; Terence Cosgrove ; Jeroen S. van Duijneveldt
• 刊名：Langmuir
• 出版年：2008
• 出版时间：October 21, 2008
• 年：2008
• 卷：24
• 期：20
• 页码：12032-12039
• 全文大小：284K
• 年卷期：v.24,no.20(October 21, 2008)
• ISSN：1520-5827

文摘

Kaolin particles were surface-treated with isobutyltrimethoxysilane (IBTMS), hydrogenated tallow (HT), and a polyisobutyl chain-based stabilizer (SAP) to make composites with polydimethylsiloxane (PDMS). IBTMS did not cover the strong acid sites on the kaolin surface and as a result a cross-linking reaction occurred for silanol-terminated PDMS. The polyisobutyl chain of SAP was found to be incompatible with PDMS and this caused aggregation of the kaolin particles. HT was the most effective at dispersing the particles into silanol-terminated PDMS. The aggregation state of the composites was characterized using rheology and microscopy. Both showed the HT-treated particles were well-dispersed in low molecular weight silanol-terminated PDMS, and they were weakly flocculated in higher molecular weight silanol-terminated PDMS. However, the same particles aggregated when dispersed in methyl-terminated PDMS. It appears the silanol-terminated PDMS acted as costabilizer through interaction with the kaolin surface. Transverse relaxation NMR was used to probe mobility of the PDMS chains in the composites. This showed little dependence on surface treatment, aggregation state, or polymer end groups. For all samples, chain mobility decreased with increasing kaolin concentration.