Controlled thin layer coating of carbon nanotube-polymer composites for UV-visible light protection

A highly dispersed solution of multi-wall carbon nanotubes (MWCNT) and counterpart polymers was prepared in aqueous solution. A thin layer coating was deposited on glass substrates by using the layer-by-layer (LBL) method. A negative charged dispersion solution of MWCNT was obtained by oxidizing the MWCNT by immersion in nitric acid. Counterpart polymers, poly(diallydimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA), were used as base materials. The zeta potential measurements of the MWCNT solution showed the strongest potential at pH 4 and strong polyanionic surfaces at pH 5. A home-made automatic LBL machine was used to coat the polycationic/anionic materials on glass substrates. The substrate was coated homogeneously by the LBL method and the transmittance from the range of ultraviolet (UV) to visible light was manipulated in the coating process. This simple technique might be effectively utilized for fabrication of micro-sensing and energy harvesting devices, and UV light protection.