Porous carbon nanotube/PMMA conductive composites as a sensitive layer in vapor sensors

A novel vapor sensor was fabricated by multi-walled carbon nanotube (MWCNT) porous composite. Poly(methyl methacrylate) (PMMA) was used as a matrix. Porous sensing films were obtained by the dry-cast non-solvent-induced phase separation (NIPS) method. The experimental results showed a remarkable improvement in sensitivity and response time of conductive porous composite vapor sensors in comparison with dense composites. The response of porous films was about five times greater than dense ones with comparable thicknesses. In addition, the effect of surface modification of nanotubes on sensitivity of porous sensors was evaluated. It was observed that functionalized CNT/PMMA porous composite sensors show higher responsiveness towards a series of organic vapors. Their response was approximately ten times greater than the response of similar sensors without functionalization of CNTs, which was explained on the basis of polar interactions of vapors on the surface of CNTs and better dispersion of nanotubes in the polymer matrix.