Low-density, stretchable, adhesive PVDF-polypyrrole reinforced gelatin based organohydrogel for UV photodetection, tactile and strain sensing applications

Veeralingam, S. and Badhulika, Sushmee (2022) Low-density, stretchable, adhesive PVDF-polypyrrole reinforced gelatin based organohydrogel for UV photodetection, tactile and strain sensing applications. Materials Research Bulletin, 150. pp. 1-12. ISSN 0025-5408

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Abstract

In this work, we report an adhesive, mechanically robust Polyvinylidene fluoride (PVDF)-polypyrrole reinforced gelatin organohydrogel as a multifunctional, and conductive platform for photodetector, highly sensitive tactile, and strain sensor applications. Morphological studies reveal the formation of PVDF/polypyrrole/gelatin microspheres enclosed with nanosheets like structure on the surface of the organohydrogel confirming the interaction of the primary amines of the cationic PVDF-polypyrrole nanocomposite with the anionic carboxylic chains of gelatin. Structural characterization confirms the characteristic scattering bands of β- phased PVDF and polypyrrole. The synthesized organohydrogel when used as a UV photodetector exhibits a rapid response time of 25 ms, excellent responsivity of 14 A/W and external quantum efficiency of 26%, caused due to the effective separation of photogenerated charge carriers at the polymer-hydrogel interface. The recoverable organohydrogel-based tactile sensor exhibited a sensitivity of 32.39 kPa−1 in the wide linear range of 0.1 – 55 kPa. Further, the strain sensor displayed a gage factor of 27.8 in the dynamic sensing range of 8.6% to 61% which is much higher than the existing class of similar reports. The sensing mechanism can be attributed to the piezo-electric polarizability of the β- phase PVDF and high conductivity of polypyrrole and gelatin in the flexible organohydrogel. The effective reinforcement of PVDF and polypyrrole in the gelatin matrix enhances the tensile strength, elastic properties, conductivity with least dependency on humidity and temperature. The polymer composite reinforced gelatin organohydrogel has a shelf-life of 30 days. © 2022

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