Remarkable self-organization and unusual conductivity behavior in cellulose nanocrystal-PEDOT: PSS nanocomposites

Aqueous suspensions of cellulose nanocrystals were blended with Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) [PEDOT:PSS], and cast into thin films. The morphology, structure and electrical properties of the resulting nanocomposite thin films were thoroughly characterized. We found that the CNC-PEDOT:PSS blends self-organize into a layered vertical stack with a pitch of 100-200nm while retaining a continuous percolation network for PEDOT. Atomic force microscopy, dynamic light scattering and multi-angle light scattering measurements confirmed the wrapping of polymer chains around the rod-like CNCs. The blended films exhibited improved molecular ordering of the PEDOT chains with concomitant improvement in the carrier mobility. The remarkable self-organization and enhanced structural order enabled the CNC-PEDOT:PSS blends to exhibit a high conductivity typical of PEDOT:PSS even when the content of the insulating CNCs in the nanocomposite was as high as 50wt%.