Elaboration and characterisation of PDMS-HTiNbO5 nanocomposite membranes

Poly(dimethylsiloxane) (PDMS)-HTiNbO5 nanocomposite membranes with various HTiNbO5 nanofiller content were prepared by melt intercalation. WAXS diffraction measurements and TEM observations have suggested that the HTiNbO5 mineral was exfoliated in the PDMS matrix. The influence of the filler in the membrane was evaluated by water diffusion, gas permeation (CO2, N2, O2, ethane and ethylene), toluene pervaporation and by CO2 sorption measurements. A filler content of only 2 wt.% in PDMS-HTiNbO5 nanocomposite membranes slows down the water diffusion significantly, and a filler content of 5 wt.% reduces also the permeability of the films for toluene. The addition of a filler content up to 10 wt.% do not significantly influences the gas permeability (P) except for CO2. The PDMS matrix appears to be highly permeable and, therefore, a decreasing effect on P is only marked for a very high HTiNbO5 content. This effect is more pronounced for CO2, the P value of which decreases by 80% when the amount of nanofiller is 40 wt.%. The sorption measurements show that the interaction between CO2 and PDMS is weak (isotherms agree with Henry’s law). The filler decreases the solubility of CO2 in the films (S = 7.94 × 10−3 and S = 5.44 × 10−3 cm3 STPcm−3 film cmHg−1 for PDMS and PDMS-HTiNbO5 40 wt.%, respectively).