Facile preparation of transparent poly (γ‐glutamic acid) modified poly (vinyl alcohol) hydrogels with high tensile strength and toughness

Abstract

In the present work, a transparent poly (γ‐glutamic acid) modified polyvinyl alcohol (γ‐PGA/PVA) hydrogel with excellent tensile strength and toughness was prepared by a simple and effective immersion method. Results revealed that γ‐PGA concentration and immersion time have great influence on the mechanical properties of prepared γ‐PGA/PVA hydrogels. The mechanical tensile strength of γ‐PGA/PVA hydrogel reached to 16.68 ± 0.43 MPa with the strain of 511.64% ± 23.38% when prepared PVA hydrogel was immersed in 20% γ‐PGA solution for 24 h (denoted as 20% γ‐PGA/PVA). Meanwhile, 20% γ‐PGA/PVA hydrogel exhibited excellent mechanical properties, such as high‐level torsion, knotting and puncture resistant, and can lift a 5 kg weight without obvious rupture. The morphology, structure, compositions and mechanism of enhanced mechanical properties were investigated. Besides the excellent mechanical properties, 20% γ‐PGA/PVA hydrogel possessed good conductivity as well as high sensitivity to external strain. Furthermore, in vitro good cytocompatibility of 20% γ‐PGA/PVA hydrogels was demonstrated by using MC3T3‐E1 cells. Therefore, the prepared 20% γ‐PGA/PVA hydrogel may provide the possibility for the applications in the field of cartilage repair/regeneration, artificial skin and human motion sensor.

Tough and anti‐swelling γ‐polyglutamic acid/polyvinyl alcohol hydrogels for wearable sensors

“…Meanwhile, the characteristic peak at 1741 cm −1 is shifted compared with the pure PVA hydrogel, determining the formations of intermolecular and intramolecular hydrogen bonds in the γ‐PGA/PVA hydrogel. For the γ‐PGA/PVA hydrogel prepared by directional crystallization, the N–H bending vibration at 1633 cm −1 and the CO tensile vibration at 1097 cm −1 gradually weaken, indicating part of the hydrogen bonds in the glue are broken 22 . On the one hand, the FC PVA hydrogel prepared by the directional crystallization method exhibits no new absorption peak during the gelation process, and no cross‐linking agent is added, indicating that the cryogel prepared by the directional crystallization method is a physical cross‐linked hydrogel.…”

“…For the γ-PGA/PVA hydrogel prepared by directional crystallization, the N-H bending vibration at 1633 cm À1 and the C O tensile vibration at 1097 cm À1 gradually weaken, indicating part of the hydrogen bonds in the glue are broken. 22 On the one hand, the FC PVA hydrogel prepared by the directional crystallization method exhibits no new absorption peak during the gelation process, and no cross-linking agent is added, indicating that the cryogel prepared by the directional crystallization method is a physical cross-linked hydrogel. On the other hand, The large number of carboxyl groups in γ-PGA is easy to form hydrogen bonds with the large number of hydroxyl groups in the PVA backbone.…”