Enhanced hydrophobicity and reduced water transport properties in alkylalkoxysilane modified Poly(butylene terephthalate) using reactive extrusion

A versatile approach for the modification of polybutylene terephthalate (PBT) surface properties without using solvent, through molten chemical modification of PBT hydroxyl end groups, with n-octyltriethoxysilane is reported. After optimization of the reactional conditions, thermally stable hydrophobic modified PBT was successfully synthesized at 240 °C with 0.3 and 1 wt. % of reagent by reactive extrusion. With the addition of 1 wt. % of n-octyltriethoxysilane, the water contact angle value increased from 80 ± 2° for raw PBT to 115 ± 4° for the modified one. Furthermore, water transport behaviors were also investigated. The modified PBT with 1 wt. % of reagent depicted a decrease of water diffusion coefficients from 1.58 × 10−10 for reference PBT to 0.64 × 10−10 cm2.s−1 for the modified one. The water permeability coefficients reduced also from 8.3 for reference PBT to 1.5 barrer for the modified PBT. [Display omitted] •PBT hydroxyl end-groups were modified with alkylalkoxysilane by reactive extrusion.•Modified PBT is hydrophobic with a water contact angle over 110°.•Surface free energy decreased from 38.7 to 24.0 mN/m (with 1 wt% of alkoxysilane).•Water permeability coefficients reduced from 8.3 to 1.5 barrer for the modified PBT.