Facile Preparation of TPU/PCL/Carbon Nanotubes Double-Percolation Conductive Nanocomposite and Evaluation for Rapid and Selective Response in Volatile Organic Compounds Applications

Severe environmental pollution due to improper emissions of volatile organic gases (VOCs) has brought a serious threat to human health, safety, the environment and socially sustainable development. Here, we report a convenient method for the preparation of conductive gas-sensitive nanocomposites by using thermoplastic polyurethane (TPU)/polycaprolactone (PCL) blends as polymer matrix and multi-walled carbon nanotubes (MWCNTs) as functional nanofiller through direct solution blending method. The experimental results indicated that the TPU phase has preferentially dispersed MWCNTs. The two-phase continuity structure of the matrix could be achieved by adjusting the ratio of TPU to PCL, and the electrical conductivity increased with the increase of the two-phase continuity. When the mass ratio of TPU and PCL was fixed at 50:50, the lowest resistivity of 2.57×10 5 Ω·m for the TPU/PCL/MWCNTs nanocomposite was obtained when MWCNTs were blended with TPU first and then with PCL. The TPU/PCL/MWCNTs nanocomposite gas-sensitive tests indicated the best gas-sensitive selectivity, responsiveness and recovery to formaldehyde compared with another target VOCs (benzene, xylene, ammonia, and ethanol). TPU/PCL/MWCNTs nanocomposites exhibited 74% gas responsiveness to formaldehyde gas at 25 o C and 500 ppm. Moreover, the responsiveness of the TPU/PCL/MWCNTs nanocomposites indicated a doughty variation linearly with the increase in formaldehyde concentration.