Piezoelectric nanocomposite films based on anionic waterborne polyurethane and barium titanate nanoparticle: Fabrication, microstructure, and property characterization

Abstract

We report the fabrication, microstructure, thermal property, and piezoelectric performance of flexible waterborne polyurethane (WPU) nanocomposite films reinforced with barium titanate (BT) nanoparticles with ~50 nm diameter. An anionic segmented WPU was synthesized via bulk polymerization, and its nanocomposite films containing 10–40 wt% BT were fabricated via aqueous dispersion casting and hot pressing. Although the BT nanoparticles interacted with the urethane groups of the WPU hard segment by inducing the separation of the semicrystalline soft segment, they were aggregated in the WPU matrix. Accordingly, the glass transition temperature of the WPU matrix decreased with BT content, but the melting temperature increased. As the BT content increased in the nanocomposite films, the thermal decomposition temperature of the WPU soft segment showed a slight decrease, while the decomposition temperature of the hard segment increased. Additionally, the residue at 600°C increased significantly from 2.0% for neat WPU film to 36.3% for the nanocomposite film containing 40 wt% BT. The piezoelectric outputs attained by the nanocomposite films increased with BT content. Under compressive stress of 23 kPa, the nanocomposite film containing 40 wt% BT was able to achieve the highest piezoelectric voltage of ~0.51 V, a current of ~43.0 nA, and an electric power of ~21.9 nW. For the nanocomposite film, a linear relationship between the piezoelectric out voltage and the applied compressive stress with a slope of ~0.0253 was also observed.Highlights Anionic waterborne polyurethane (WPU) with hard/soft segments is synthesized. Barium titanate (BT) nanoparticles are adopted as a piezoelectric nanofiller. WPU/BT nanocomposites are manufactured by dispersion casting and hot pressing. Specific interactions between BT nanoparticles and WPU hard segments exist. Piezoelectric outputs of nanocomposites increase with BT content and stress.

Castor‐oil derived polyurethane/barium titanate piezoelectric smart composite coatings for energy harvesting applications: Prediction and experimental characterization of electro‐elastic properties

“…Due to the non‐availability of dielectric constant values for COPU/BTO composites, in our study we have compared experimentally evaluated results with piezoelectric polymer matrix composites, having BTO as inclusion and different non‐piezoelectric polymer as matrix phases. For example, Seo et al 70 also observed that the dielectric constant decreases with increasing frequency from 20 Hz to 2 MHz for neat water‐based polyurethane as well as polyurethane/BTO composites with BTO content in the range of 10 wt.% to 40 wt.%. This matches our experimental observation of monotonic decrease of dielectric constant as a function of frequency for all compositions of COPU/BTO composites studied in this work.…”

“…A direct comparison with existing literature is difficult because of the differences in experimental procedure as well as differences in the materials used and poling conditions used. For example, water‐soluble PU/40 wt.% BTO nanocomposite (with average BTO nanoparticle size of ~50 nm) has been reported to generate V OC and I SC values of ~0.51 V and ~ 43 nA under a compressive stress of 23 kPa 70 . The V OC reported by Seo et al 70 is close to the V OC value of 0.61 V obtained for CPBT‐5 (which has a comparable BTO microparticle content of ~38 wt.%) when it is subjected to a similar compressive stress of ~22 kPa; however, the I SC value of ~9 nA is significantly lower than that reported by Seo et al 70 …”

Deformation Mode-Sensitive Piezoelectric Hybrid Nanocomposite Films Based on Anionic Waterborne Polyurethane, Barium Titanate Nanoparticles, and Boron Nitride Nanosheets

“…To assess the dispersion states of BT nanoparticles and BN nanosheets within the WPU matrix, SEM images of cross sections of the nanocomposite films with 40 wt % filler contents of different BT/BN ratios were obtained, as represented in Figure . For the nanocomposite film (WPU-T40) with only 40 wt % BT nanoparticles (Figure A), BT nanoparticles were agglomerated in the WPU matrix, which may be caused by high filler content and high density (∼6.02 g/cm 3 ) of BT nanoparticles during the aqueous dispersion casting. ,, It has been reported that the aggregation of BT nanoparticles within polymer matrices can be advantageous for enhancing piezoelectric performance . The reason is that when a compressional force is applied, the aggregated BT nanoparticles, which are also aligned by electric poling, induce a substantial dipole moment and thus lead to a significant potential difference.…”

“…The synthesis of an anionic WPU and the fabrication of WPU aqueous dispersion were conducted through the procedure described in the previous article. , A series of WPU nanocomposite films, including BT and/or BT nanofillers, were manufactured via an efficient dispersion casting process, as schematically presented in Figure . An aqueous dispersion with 24 wt % WPU solid content was prepared by ultrasonication for 1 h. Predetermined amounts of BT nanoparticles and/or BN nanosheets were dispersed in DMF, which were then added into the WPU aqueous dispersion and ultrasonicated for 1 h. The mixed dispersion was applied onto a polypropylene plate and dried at 40 °C.…”