Tuning piezoelectric properties in elastomeric polyurethane nanocomposites utilizing cellulose nanocrystals

Abstract

Flexible piezoelectric nanocomposites have been the subject of a lot of recent research due to the development and use of wearable electronic devices and the increasing need for new harvesting devices and sensors due to increasingly intelligent and interconnected cities. In this study, flexible piezoelectric nanocomposites using elastomeric polyurethane (PU) as matrix, and lead zirconate titanate (PZT) as active phase, were produced using cellulose nanocrystals (CNC) as the third phase. The study describes the effect of CNC insertion on the morphology, thermal, electrical, and piezoelectric properties of the nanocomposites. It points out that the CNCs not only act to cause greater dispersion of the ceramic grains in the matrix, but also to lead to greater polarization effectiveness of the ceramic grains, resulting in a longitudinal piezoelectric coefficient (d33) increase of more than 370%, as compared with biphasic composites dependent on the ceramic and nanocrystals content.

Dielectric, electric, and piezoelectric properties of three‐phase piezoelectric composite based on castor‐oil polyurethane, lead zirconate titanate particles and multiwall carbon nanotubes

“…It can be observed that PZT has little influence on the σ dc values of the PUR/PZT piezoelectric composite. This small increase in σ dc can be attributed to the ionic and electronic conduction processes that occur preferentially in PZT grains 42,43 . On the other hand, MWCNT impacted on the σ dc value of three‐phase PUR‐MWCNT/PZT piezoelectric composite.…”

“…The stronger decrease in σ dc value to piezoelectric composite containing 3 wt.% MWCNT (PUR‐MWCNT3/PZT), when PZT concentration increased, can be related to barrier effects that arise by breaking the connectivity of the percolative conduction pathway formed by MWCNT 44 . For high PZT fractions, free volume is reduced in the matrix, therefore constraining MWCNT to minute polymeric regions and facilitating their interaction through van der Waals bonds, which results in aggregation 43 . The increase in PZT concentration also increases the energy barrier that charge carriers must overcome to flow through a material when an electric field is imposed.…”

“…On the other hand, samples with 1 wt.% of MWCNT (PUR‐MWCNT1/PZT) showed an opposite behavior with respect to the PUR‐MWCNT3/PZT samples, that is, when the PZT concentration increased by 10 vol.% there was an increase in the σ dc value of the PUR‐MWCNT1/PZT three‐phase composite. Below the percolation, for lower PZT concentrations, the reduction in free volume of dispersion caused by piezoelectric particles acts to bringing the nanotubes closer together, thus improving the formation of conduction pathways and facilitating the hopping processes 43 …”

“…This small increase in σ dc can be attributed to the ionic and electronic conduction processes that occur preferentially in PZT grains. 42,43 On the other hand, MWCNT impacted on the σ dc value of three-phase PUR-MWCNT/PZT piezoelectric composite. For instance, in samples containing 10 vol.% PZT, there was a 5 and 7-fold increase in σ dc values for samples with 1 and 3 wt.% of MWCNT, respectively, when compared to the PUR/PZT two-phase composite sample with 10 vol.% PZT.…”

Piezoelectric Materials: Properties, Advancements, and Design Strategies for High-Temperature Applications

“…It is widely acknowledged that to boost the piezoelectric performance of pure piezoelectric materials, incorporating other components to construct hybrid systems demonstrates a powerful approach to make up for the shortcomings of each component and to exploit synergy effects [ 109 , 110 , 111 , 112 , 113 , 114 ]. Baur et al [ 109 ] enhanced the piezoelectric performance of PVDF with carbon fluoropolymer nanocomposites.…”