Flexible Composites with Variable Conductivity and Memory of Deformation Obtained by Polymerization of Polyaniline in PVA Hydrogel

Abstract

Flexible materials that provide an electric, magnetic, or optic response upon deformation or tactile pressure could be important for the development of smart monitors, intelligent textiles, or in the development of robotic skins. In this work we demonstrate the capabilities of a flexible and electrically conductive polymer material that produces an electrical response with any deformation, namely the electrical resistance of the material changes proportionally with the deformation pressure. Furthermore, the material exhibits a memory effect. When compressed beyond the elastic regime, it retains the memory of the plastic deformation by increasing its resistance. The material was obtained by in situ polymerization of semiconducting polyaniline (PANi) in a polyvinyl alcohol/glycerol (PVA/Gly) hydrogel matrix at −17 °C. Upon drying of the hydrogel, an elastomer composite is obtained, with rubber-like characteristics. When compressed/decompressed, the electrical resistance of the material exhibits an unusually long equilibration/relaxation time, proportional with the load applied. These phenomena indicate a complex relaxation and reconfiguration process of the PANi/PVA elastomer matrix, with the shape change of the material due to mechanical stress.

Unidirectional Nanopore Dehydration Induces an Anisotropic Polyvinyl Alcohol Hydrogel Membrane with Enhanced Mechanical Properties

“…The temperature affects the velocity at which the water molecules flow unidirectionally through the nanopores, and could, thus, alter the overall transformation of the PVA chains into a physically crosslinked three-dimensional network. From a physicomechanical point of view, the influence of the preparation temperature on the tensile strength, elongation at break, and modulus of elasticity of the tested PVAHMs seems to mirror a behavior specific to a rubber-like state or simply a rubbery state [ 37 ]. Thus, in such a state, the PVA chain segments between the crosslinking points (well-aligned microcrystalline regions) undergo a micro-Brownian motion with larger and larger intensity as the temperature increases [ 38 ].…”

Nanofibrous electroconductive scaffolds composed of poly(vinyl alcohol) and modified polyaniline for skin tissue engineering application

“…In addition, blending or grafting of PANI onto this polymer lead to a biocompatible polymeric material with proper mechanical properties. [32][33][34] Some electrically conductive nanofibrous scaffolds have developed for STE based on PANI. A series of PANI/ chitosan nanofibers with different PANI content (1:3, 3:5, and 1:1) were fabricated by Moutsatsou et al, using electrospinning method for STE.…”

“…In this assay, poly(vinyl alcohol) (PVA) was used as a suitable hydrophilic, biocompatible, and biodegradable polymer for more biocompatibilization of PANI. In addition, blending or grafting of PANI onto this polymer lead to a biocompatible polymeric material with proper mechanical properties 32–34 …”

One‐pot preparation of tough, anti‐swelling, antibacterial and conductive multiple‐crosslinked hydrogels assisted by phytic acid and ferric trichloride

“…8 Particularly, with the rapid development progress of flexible electronic technology, hydrogel-based flexible electrodes and sensors have gained increasing attention in the application of human movement detection, wearable electronic devices and health monitoring. [9][10][11] Recently, many synthetic polymers have been used as raw materials to construct hydrogels. Among various synthetic polymers, polyvinyl alcohol (PVA), a hydrophilic polymer with abundant hydroxy groups on its polymer chains, has favorable biocompatibility, nontoxicity, gel-forming property and biodegradability, 12,13 which make it gain growing interest in the preparation of hydrogels for the biomedical applications.…”

“…Because of similar characteristics to the extracellular matrix (ECM) of natural soft tissues, hydrogels have attracted considerable attention for their multifarious applications in biomedical areas such as tissue engineering, 3 drug delivery, 4 flexible sensors, 5–7 and soft robotics 8 . Particularly, with the rapid development progress of flexible electronic technology, hydrogel‐based flexible electrodes and sensors have gained increasing attention in the application of human movement detection, wearable electronic devices and health monitoring 9–11 . Recently, many synthetic polymers have been used as raw materials to construct hydrogels.…”