Poly(vinyl alcohol)–Poly(ethylene glycol) Double-Network Hydrogel: A General Approach to Shape Memory and Self-Healing Functionalities

Abstract

A double-network polymer hydrogel composed of chemically cross-linked poly(ethylene glycol) (PEG) and physically cross-linked poly(vinyl alcohol) (PVA) was prepared. When the hydrogel (70 wt % of water) is subjected to freezing/thawing treatment under strain, the enhanced physical network as a result of crystallization of PVA chains can stabilize the hydrogel deformation after removal of the external force at room temperature. Subsequent disruption of the physical network of PVA by heating allows for the recovery of the initial shape of the hydrogel. Moreover, the double-network hydrogel exhibits self-healing capability stemming from the physical network of PVA by virtue of the extensive interchain hydrogen bonding between the hydroxyl side groups. This study thus demonstrates a general approach to imparting both the shape memory and self-healing properties to chemically cross-linked hydrogels that otherwise do not have such functionalities. Moreover, by making use of the fixed hydrogel elongation, the effect of anisotropy arising from chain orientation on the self-healing was also observed.

Ultrathin PEDOT:PSS/rGO Aerogel Providing Tape‐Like Self‐Healable Electrode for Sensing Space Electric Field with Electrochemical Mechanism

“…[9] It is difficult to keep the active layer uniformly distributed on substrate with the spray method. [19] In addition, the poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) produces a self-healing conductive polymer film by thermal film formation, with high transparency and rich applicability. [12][13][14] The lifetime is one of the important indicators for evaluating the performance of smart electronic devices.…”

Synthetic self-assembled homogeneous network hydrogels with high mechanical and recoverable properties for tissue replacement

“…However, the translucent or even non-transparent hydrogels were obtained using similar compositions by other synthetic methods. 35,36 The asobtained hydrogels maintained their transparency irrespective of the concentration of PVP (Fig. 1b).…”

“…Notably, the transparency of the hydrogels enhanced with the increasing concentration of PVP, indicating that the hydrogels with a HN structure did not induce light scattering. 35 These hydrogels were synthesized based on the ketalization reaction catalyzed by acid between ketones and alcohols, in which C-O-C ether bond could be constructed by electrophilic rearrangement via removal of water molecule on the mutually reactive functional side-groups (ketone groups and alcoholic hydroxyl groups). 37,38 In this work, the alcoholic hydroxyl side-groups of PVA chain and ketone groups of PVP chain induced the self-assembly in an acid catalysis, obtaining a 1,3-dioxane polymer (Fig.…”

“…3d). The light scattering was negligible, which derives from the crystalline microdomains of PVA caused by hydrogen bonds in intermolecular chains, 35 inferring that the alcoholic hydroxy groups of PVA were consumed during the self-assembled process. The special side-groups served as cross-linking centers for polymerization of polymer monomers based on the electrophilic rearrangement principle, which was critical for the formation of HN hydrogels.…”

Supramolecular hydrogel of poly(vinyl alcohol)/chitosan: A dual cross‐link design

“…[16] For a long time, PVA has obtained great focus due to its desirable advantages, such as biocompatibility and nontoxicity. [20] The crystalline is an important and remarkable characterization for physically cross-linked PVA hydrogel obtained by freezing/ thawing experiment. Generally, no matter how to use PVA hydrogel, nontoxicity, or low toxicity is necessary.…”