Preparation of Long‐Chain‐Alkyl Siloxanes Bridged by Carbon‐Sulfur Bond via Thiol–Ene Reaction

ABSTRACT Long‐chain‐alkyl siloxanes were commonly used as hydrophobic treatment agents in cotton fabrics. In this work, long‐chain‐alkyl siloxanes (S‐Siloxanes) were prepared by thiol–ene reaction between polyvinylmethylsiloxanes (SiCC) and 1‐pentanethiol. Thermal behavior, glass transition temperature (Tg), crystallization property, and hydrophobic treatment performance were investigated and compared with those of commonly used long‐chain‐alkyl siloxanes (C‐Siloxanes) prepared via hydrosilylation reaction with platinum as a catalyst. The results showed that S‐Siloxanes were thermally stable up to 350°C and possessed similar Tg and crystallization performance as C‐Siloxanes. Water contact angles of glasses and cotton fabrics treated by S‐Siloxanes reached 87.67° and 96.33° respectively, which were significantly increased compared to untreated glasses and cotton fabrics of 36.27° and 0°. The results were similar for glasses and cotton fabrics treated by C‐Siloxanes. This work provides a milder and greener method to synthesize long‐chain‐alkyl siloxanes.