Controlling the Organization of PEDOT:PSS on Cellulose Structures

Composites of biopolymers and conducting polymers are emerging as promising candidates for a green technological future and are actively being explored in various applications, such as in energy storage, bioelectronics, and thermoelectrics. While the device characteristics of these composites have been actively investigated, there is limited knowledge concerning the fundamental intra-component interactions and the modes of molecular structuring. Here, using cellulose and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) it is shown that the chemical and structural make-up of the surfaces of the composite components are critical factors that determine the materials organization at relevant dimensions. AFM, TEM and GIWAXS measurements show that when mixed with cellulose nano-fibrils, PEDOT:PSS organizes into continuous nano-sized bead-like structures with an average diameter of 13 nm on the nano-fibrils. In contrast, when PEDOT:PSS is blended with molecular cellulose, a phase-segregated conducting network morphology is reached, with a distinctly relatively lower electric conductivity. These results provide insight into the mechanisms of PEDOT:PSS crystallization and may have significant implications for the design of conducting-biopolymer composites for a vast array of applications.