Synthesis and characterisation of silica hybrids based on poly(ε-caprolactone-b-perfluoropolyether-b-ε-caprolactone)

Poly(ε-caprolactone-b-perfluoropolyether-b-ε-caprolactone) (PCL-PFPE-PCL) triblock copolymers having hydroxy end groups were readily functionalised with triethoxysilane end groups by reactions with 3-isocyanatopropyltriethoxysilane. Organic-inorganic hybrids were prepared by using the sol-gel process in the presence of tetraethoxysilane and hydroxy or triethoxysilane terminated PCL-PFPE-PCL. Fully transparent hybrid materials with high content of organic matter were obtained only in the case of alkoxysilane functionalised copolymers. For such systems the PCL-PFPE-PCL copolymer was so intimately mixed with the inorganic network to prevent crystallisation of the PCL segments. The progress of the sol-gel reaction was limited by the early vetrification of the reactive system, while the interpenetration of the organic phase was enhanced by curing the samples at 100 °C.