Electromechanical properties characterization of chitosan-based bionanocomposites through piezoelectric force microscopy

The electromechanical response of biopolymer-based composites constitutes an important field of research for flexible and sustainable materials in electronics. Piezoactive properties of polysaccharides, such as chitosan, have been reported[1]. Nevertheless, it is still challenging to identify the origin of its electromechanical performance which is different depending on the fabrication factors and measurement methodologies. In this work, a set of chitosan-based bionanocomposite films were fabricated without and with barium titanate and different carbon structures (carbon nanotubes, carbon nanofibers, graphite powder). The films were dried under corona poling to promote the orientation of the nanostructures inside the material[2]. A systematic characterisation of the films was done through the piezoelectric force microscopy (PFM) technique including the analysis of the second harmonic generation, and Kelvin Probe Force Microscopy (KPFM)[3]. The analysis of the second harmonic generation response was done to identify the contribution of distinct electromechanical mechanisms at the microscale. In most cases, the second harmonic signal is higher than the first harmonic signal which suggests that the measured response in chitosan-based films is dominated by electrostriction, electrostatics, or charge injection phenomena. This work allows us to elucidate and clarify the performance of polysaccharides-based bionanocomposites for their future implementation in flexible electronic applications.

[1] A. Hänninen, E. Sarlin, I. Lyyra, T. Salpavaara, M. Kellomäki, S. Tuukkanen, Carbohydr. Polym. 2018, 202, 418.

[2] H. Cui, R. Hensleigh, D. Yao, D. Maurya, P. Kumar, M. G. Kang, S. Priya, X. (Rayne) Zheng, Nat. Mater. 2019, 18, 234.

[3] B. J. Rodriguez, S. V. Kalinin, J. Shin, S. Jesse, V. Grichko, T. Thundat, A. P. Baddorf, A. Gruverman, J. Struct. Biol. 2006, 153, 151.