Electromechanical sensors based on carbon nanotube networks and their polymer composites

Abstract

A network of entangled multiwall carbon nanotubes and the composite consisting of filter-supported multiwall carbon nanotube network are conductors whose conductivity is sensitive to compressive stress both in the course of monotonic stress growth and when loading/unloading cycles are imposed. The testing has shown as much as 100% network conductivity increase at the maximum applied stress. The entangled carbon nanotube networks are prepared by vacuum filtration method and peeled off from the filter. The carbon nanotubes are used in pristine condition or chemically functionalized. The filter-supported entangled networks are prepared by the nanotube dispersion filtration through a non-woven flexible polystyrene filter. The nanotubes infiltrate partly into the filter surface pores and link the accumulated filtrate layer with the filtering mat. The filter-support increases nanotube network mechanical integrity, the composite tensile ultimate strength and affects favorably the composite electrical resistance. Other obvious effect of the supporting polymer is reduction of the resistance temperature dependence. Moreover, the conductivity of carbon nanotube networks manifests also organic vapor dependence. The dependence is reversible, reproducible, selective as well as influenced by nanotube oxidation. © 2011 Springer-Verlag Berlin Heidelberg.