Synthesis,film morphology and performance of novel crosslinked polysiloxane with end-capped epoxy groups on cotton substrates

An epoxy group-terminated polyvinylmethylsiloxane (EPVMS) was firstly prepared via the cohydrolysis/condensation reaction of octamethylcyclotetrasiloxane (D₄), 2,4,6,8-Tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (D₄V), and epoxy group-terminated polydimethylsiloxane (ETP) under a base catalyst. Then, the EPVMS was reacted with polymethylhydrosiloxane oligomer (PHMS) by hydrosilylation to develop novel crosslinked polysiloxane with end-capped epoxy groups (CLPS). The chemical structure and the thermal property of the as-prepared products were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectra (¹H/¹³C NMR) and thermogravimetric analysis (TGA). Finally, the CLPS was applied as the finishing agent to treat the cotton fabrics. The film morphology and the surface properties were examined with scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), contact angle measurements, and other instruments. FT-IR and NMR results confirmed the structure of the resultants. The crosslinked polysiloxane CLPS showed better thermal stability than the uncrosslinked polysiloxane EPVMS. The CLPS film on cotton fabric surface seemed to be smooth compared to the control by SEM. However, owing to the crosslinked structure, the CLPS film on silicon-wafer was inhomogeneous and had a few weak or strong peaks. At 5 nm data scale and in 2×2 μm² scanning field, the root mean square roughness of CLPS film reached to 0.414 nm. XPS analysis further demonstrates that there was a CLPS film covered on the cotton surface. Hydrophobicity of the CLPS treated fabric was superior to that of the EPVMS treated one. Whiteness of the treated fabrics by CLPS and EPVMS did not change at all compared to the control. The softness of the two treated fabrics was both better than that of control and particularly the softness of the EPVMS treated fabrics was preferable. The CLPS treated fabric possessed good washing durability.