Abstract
Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.
Highlights
We showed that with the increase in the content of mineral nanofiller in the polysiloxane matrix, the rate and efficiency of the hydrosilylation reaction decreased [27]
Our research has shown that the presence of a mineral nanofiller reduces the efficiency of the hydrosilylation reaction and the degree of cross-linking of the entire polysiloxane matrix
The study investigated the effect of montmorillonite modified with various quaternary ammonium salts on the cross-linking efficiency of polysiloxanes
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Montmorillonite (Mt) is the best-known member of a smectite group of clay minerals and the most commonly used layered aluminosilicate for the preparation of clay–polymer nanocomposites. This is due to its high availability, low cost, capacity for swelling, and ion exchange properties. Mt has a large surface area and high average aspect ratio (length-to-diameter ratio), good mechanical strength, and can undergo delamination [1,2,3]
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