(357b) Cellulose Nanocrystal Templates for Transparent Conductive Films

There is great interest in using biorenewable materials for sustainable, next generation technologies. Here we present the use of cellulose nanocrystals (CNCs), derived from wood pulp, as a unique template for growing conductive silver nanoparticles (Ag NPs) as a potentai replacement for indium tin oxide and related transparent conductive materials. We demonstrate the potential to successfully nucleate and grow AgNPs on CNC templates in the form of a stable, optically clear and transparent aqueous colloid. Our approach to generating the Ag/CNC templated nanoparticles is unique compared to traditional metallic NP colloid growth schemes, in that we take advantage of starving the particle nucleation and growth processes to control NP size and resultant nanocomposite morphology. The co-integrated CNC templates serve as nucleation sites for NP growth. The CNC templating agent facilitates systematic alignment of conductive nanoparticles along its rigid backbone. Our results show the impact of CNC surface chemistry and functional group density on the CNC/Ag nanocomposite morphology, including Ag particle size/shape and population density on the CNC template.

We further present preliminary results to generate robust 3D percolating networks of CNC/Ag particles in the form of homogenous, optically transparent nanocomposite films and conformal coatings. Traditionally, electrical percolation requires exceeding a critical loading level with which particles are sufficiently close in a 3-D network to enable interparticle charge mobility for a conductive pathway. Our results demonstrate that the CNC/Ag colloids can be processed under ambient conditions into optically transparent and electically conductive films. Further, we shed light on the relationship of nanocomposite film structure/morphology, film formation approach, and measured electrical conductivity/optical transparency.