@article{3cbbb821849e496689e7937c26ffa9da,
title = "Integration of polypyrrole electrode into piezoelectric PVDF energy harvester with improved adhesion and over-oxidation resistance",
abstract = "Smart textiles for wearable devices require flexibility and a lightweight, so in this study, a soft polypyrrole (PPy) electrode system was integrated into a piezoelectric polyvinylidenefluoride (PVDF) energy harvester. The PVDF energy harvester integrated with a PPy electrode had the piezoelectric output voltage of 4.24-4.56 V, while the PVDF energy harvester with an additional aluminum-foil electrode exhibited 2.57 V. Alkaline treatment and chemical vapor deposition with n-dodecyltrimethoxysilane (DTMS) were employed to improve the adhesion between the PVDF and PPy and the resistance to over-oxidation in aqueous solutions. The PVDF film modified by an alkaline treatment could have the improved adhesion via the introduction of polar functional groups to its surface, which was confirmed by the ultrasonication. The surface hydrophobicity of the PPy electrode was enhanced by the DTMS coating, resulting in the improvement of the resistance to over-oxidation with a water contact angle of 111°. Even with the hydrophobic coating, the electrodes remained electroconductive and continued to transfer an electric charge, maintaining the piezoelectricity of the PVDF film. The developed electrode-integrated energy harvester is expected to be applied to smart textiles because it offers the advantages of efficient piezoelectric generation, flexibility, and durability.",
keywords = "Durability, Electroconductivity, Electrode, Energy harvester, Flexibility, Piezoelectricity, Poly(vinylidene fluoride), Polypyrrole",
author = "Kyungha Baik and Sohyun Park and Changsang Yun and Park, {Chung Hee}",
note = "Funding Information: This work was supported by a grant fromthe National Research Foundation (NRF) of Korea funded by the Korean government (Ministry of Science and ICT) (no. NRF-2018R1A2B6003526, and NRF-2016M3A7B4910940). Funding Information: In this study, PPy electrodes were combined with PVDF films for use in a flexible and practical piezoelectric energy harvester. The PVDF energy harvester integrated with PPy electrode had the piezoelectric energy harvester. The PVDF energy harvester integrated with PPy electrode had the piezoelectric output voltage of 4.24–4.56 V, while the PVDF energy harvester with an additional piezoelectric output voltage of 4.24–4.56 V, while the PVDF energy harvester with an additional aluminum-foil electrode exhibited 2.57 V. The adhesion between the PVDF and PPy was modified aluminum-foil electrode exhibited 2.57 V. The adhesion between the PVDF and PPy was modified by by alkaline treatment, and enhancements in the resistance to over-oxidation by the application of a alkaline treatment, and enhancements in the resistance to over-oxidation by the application of a hydrophobic DTMS coating were evaluated. The morphology of PPy without alkaline treatment was a hydrophobic DTMS coating were evaluated. The morphology of PPy without alkaline treatment was continuous granular matte structure, while a semi-discrete structure was observed on the PVDF films a continuous granular matte structure, while a semi-discrete structure was observed on the PVDF treated with the alkaline solution. Improved adhesion between the alkaline-treated PVDF and PPy films treated with the alkaline solution. Improved adhesion between the alkaline-treated PVDF and was verified through ultrasonication tests. The PPy electrode polymerized on the alkaline-treated PPy was verified through ultrasonication tests. The PPy electrode polymerized on the alkaline-PVDF was not removed or damaged, and the surface resistivity was increased by 5.34%. Although the treated PVDF was not removed or damaged, and the surface resistivity was increased by 5.34%. surface resistivity of the PPy electrode became higher with a hydrophobic coating, its piezoelectric Although the surface resistivity of the PPy electrode became higher with a hydrophobic coating, its output voltage and current were reduced by 6.92% and 4.17%, respectively. The electron transfer was piezoelectric output voltage and current were reduced by 6.92% and 4.17%, respectively. The electron not adversely affected by the increased hydrophobicity, while the hydrophobic coating enhanced the transfer was not adversely affected by the increased hydrophobicity, while the hydrophobic coating over-oxidation resistance of the PPy electrode. enhanced the over-oxidation resistance of the PPy electrode. Alkaline treatment and the DTMS coating via CVD reinforced the adhesion between PVDF and Alkaline treatment and the DTMS coating via CVD reinforced the adhesion between PVDF and PPy and improved the resistance to over-oxidation of PPy electrodes. Furthermore, the low cost of PPy, PPy and improved the resistance to over-oxidation of PPy electrodes. Furthermore, the low cost of its simple polymerization process, and the potential for large-scale manufacture make PPy a promising PPy, its simple polymerization process, and the potential for large-scale manufacture make PPy a electrode material. Since the PPy electrode was applied to PVDF films without any adhesive paste, their promising electrode material. Since the PPy electrode was applied to PVDF films without any flexible and stretchable properties were not significantly affected. The feasibility of PVDF as an energy adhesive paste, their flexible and stretchable properties were not significantly affected. The feasibility harvester in wearable devices was reinforced by the strong connection between the PPy electrode and of PVDF as an energy harvester in wearable devices was reinforced by the strong connection between the PVDF film. More precise control of the PPy structure is suggested to achieve the superhydrophobic the PPy electrode and the PVDF film. More precise control of the PPy structure is suggested to achieve or self-cleaning properties, and such improvements would prevent degradation of the electrode upon the superhydrophobic or self-cleaning properties, and such improvements would prevent exposure to rain or pollutants. Based on the results of this research, we expect further development degradation of the electrode upon exposure to rain or pollutants. Based on the results of this research, of the flexible and stretchable properties of piezoelectric energy harvesters, weight-reduction, and we expect further development of the flexible and stretchable properties of piezoelectric energy advances in wearable device technology. harvesters, weight-reduction, and advances in wearable device technology. Author Contributions: Conceptualization, K.B. and C.H.P.; methodology, K.B.; formal analysis, K.B., S.P., C.Y. AanudthCo.rHC.Po.;nwtrribituintgio—nso:r Cigoinnaclepdtruaaftlipzraetipoanr,a Ktio.Bn., aKn.dB .C, S.H.P..P, a.;nmdeCth.Yo.d; owlorigtiyn,gK—.Br.e; vfoierwmaaln adneadlyitsiinsg, K, K.B.B., .Sa.nPd., CC..YY..; and C.H.P.; writing—original draft preparation, K.B., S.P., and C.Y.; writing—review and editing, K.B. and C.Y.; Funding: This work was supported by a grant from the National Research Foundation (NRF) of Korea funded by the Korean government (Ministry of Science and ICT) (no. NRF-2018R1A2B6003526, and NRF-2016M3A7B4910940). Funding: This work was supported by a grant from the National Research Foundation (NRF) of Korea funded by the Korean government (Ministry of Science and ICT) (no. NRF-2018R1A2B6003526, and NRF-2016M3A7B4910940). Publisher Copyright: {\textcopyright} 2018 by the authors.",
year = "2019",
doi = "10.3390/POLYM11061071",
language = "English",
volume = "11",
journal = "Polymers",
issn = "2073-4360",
publisher = "MDPI AG",
number = "6",
}