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In this work, we prepare cellulose nanopapers of high mechanical performance and with the electrical conductivity of a semiconductor. Cellulose nanofibers (CNF) from bleached softwood pulp were coated with polypyrrole (PPy) via in situ chemical polymerization, in presence of iron chloride (III) as oxidant agent. The structure and morphology of nanopapers were studied, as well as their thermal, mechanical and conductive properties. Nanopaper from pure CNF exhibited a very high tensile response (224MPa tensile strength and 14.5GPa elastic modulus). The addition of up to maximum 20% of polypyrrole gave CNF/PPy nanopapers of high flexibility and still good mechanical properties (94MPa strength and 8.8GPa modulus). The electrical conductivity of the resulting CNF/PPy nanopaper was of 5.2 10(-2)Scm(-1), with a specific capacitance of 7.4Fg(-1). The final materials are strong and conductive nanopapers that can find application as biodegradable flexible thin-film transistor (TFT) or as flexible biosensor., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This work demonstrates the significant interphase region of polyimide/titanium dioxide nanofiber nanocomposite. Interphase characteristics of nanocomposites were calculated using Interphase Power Model. It revealed that the interphase volume fraction and interphase dielectric constant were proportionately increased with filler loading at least up to 20%. The increasing trend of interphase dielectric constant signifies a loosely bounded polymeric chain onto the filler surfaces giving the interphase volume constant k as 2.05. However, the ratio of interphase volume to that of the filler volume progressively decreased which was attributed to the effect of agglomeration of filler and percolation of overlapping interphase region to yield an average interphase thickness of 81 ± 10 nm. By designing the complex function of interfacial interaction through the surface activity between the filler and matrix, the interphase region can be appropriately monitored in understanding its effects on glass transition and dielectric constant of the nanocomposites. [ABSTRACT FROM AUTHOR]

In the current work, flexible, lightweight, and strong conductive nanopapers based on cellulose nanofibers (CNFs) with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and/or polypyrrole (PPy) were prepared by following a mixing and in situ chemical polymerization method. A successful homogeneous coating of PEDOT:PSS on cellulose nanofibers occurred by means hydrogen-bonding interactions between the hydroxyl functionalized CNF and the electronically charged PEDOT:PSS, as shown by FTIR spectra. The electrical conductivity and the specific capacitance of CNF-PEDOT:PSS nanopapers were 2.58 S cm −1 and 6.21 F g −1 , respectively. Further coating of PPy produced a substantial improvement on the electrical conductivity (10.55 S cm −1 ) and the specific capacitance (315.5 F g −1 ) of the resulting CNF-PEDOT:PSS-PPy nanopaper. A synergistic phenomenon between both conductive polymers supported the high electrical conductivity and specific capacitance of the ternary formulation. Moreover, CNF-PEDOT:PSS-PPy nanopaper showed higher mechanical properties and it was more flexible than the nanopaper containing only polypyrrole conducting polymer (CNF-PPy). It is concluded that the good mechanical, electrical and electrochemical properties of the ternary formulation can apply for smart nanopaper in flexible electronics and energy storage devices. [ABSTRACT FROM AUTHOR]