Carbon Nanotube Copolymer Composites for use in Conductive and Semi-Conductor Applications
Summary
Carbon nanotubes (CNT’s) are finding varied uses as fillers for composite materials for use in electrically conductive films, electrostatic coatings and enhancements to physical strength. The price of CNT’s has fallen over the last few years and the price varies with quality, purity, quantity, size, functionalization and presentation. For MWCNT’s the price varies from $5 to $25 per gram, for SWCNT’s $45 to $300 per gram. Although costs are expected to reduce further in future, there is a huge financial incentive to reduce CNT loadings for conductive materials. Carbon nanotubes are sold either as masterbatch solutions or as bundled dried tubes for health and safety reasons. One of the greatest problems with these materials is ensuring that the CNT’s are exfoliated and that they connect within the polymer matrix (percolate). The less CNT’s required for percolation (electrical conductivity), the lower the costs will be and the better the optical properties of the polymeric materials should be.
The block copolymers developed within FYSC (Department of Physical Chemistry and Polymer Science) are produced using aqueous emulsion and dispersion techniques offering a controlled and facile route to polymer synthesis and composite materials. Composites are prepared by either mixing preexfoliated CNT solutions (current technology) or by directly dispersing/exfoliating CNT’s into the concentrated aqueous polymer solutions (improved methodology.)
Application of Technology
1) Exfoliation of CNT’s into dilute polymer solutions to create masterbatches
2) Direct dispersion of CNT’s into concentrated polymer batches
3) Polymer dispersions can be used for conductive coatings
4) Flexible methods of application and wide range of substrates
5) Use in conductive inks
6) Easy preparation of conductive thin films (40 μm to 500 μm)
7) Co-polymers can be tailored to contain a wide variety of polymers with interesting properties
8) Materials are easy to modify
9) Future uses in solar cell applications, plastic wires, synthetic tissue engineering, sheet printed circuit boards and flexible electrodes
10) A future beyond CNT’s – systems can be used for preparation and dispersion of graphene, or metallic nanowires