Poly(vinyl alcohol) Nanocrystal-Assisted Hydrogels with High Toughness and Elastic Modulus for Three-Dimensional Printing

Abstract

Flexibility, diversity, and applicability in complicated situations are urgently required for next generation of tough hydrogels with good processability. To achieve this good performance, complicated chemical polymerization is conventionally involved in the preparation of tough hydrogels, which is tedious, energy-consuming, detrimental to the environment, and hard to scale up. In contrast, physically cross-linking primarily the electrostatic force is always adopted as complementary to chemical cross-linking. Here we propose a simple, nonpolymerization method to develop a novel type of dual physically cross-linked tough hydrogel, which consists of poly­(vinyl alcohol) (PVA) crystallite cross-linked network, and hyaluronic acid–Fe3+ physically cross-linked network. Instead of using electrostatic interaction, nanosized PVA crystallites were chosen as major cross-linking sites for the primary network of the hydrogel. By annealing the freeze–thaw hydrogel followed by the Fe3+-carboxylic group complexation to construct the second network, extraordinary mechanical performance including excellent tensile strength (∼8 MPa), remarkable toughness (∼19.6 MJ/m3) and high elastic modulus (∼10 MPa) was successfully achieved. Especially, the precursor solution with viscoelastic properties was demonstrated to as a “new” type of ink for three-dimensional (3D) printing with no UV curing is required. Such design provides a simple and new avenue for the preparation of tough hydrogels featured with 3D printing processability and we believe that the design can be potentially applied for building future soft devices.

Highly stretchable gamma-irradiated poly (vinyl alcohol)/Tannic acid composite hydrogels with superior transparency and antibacterial activity

“…Hydrogels are polymer materials with a three-dimensional network structure containing large amounts of water, and are promising materials for various applications, such as sensing [1,2], soft actuators [3,4], drug controlled release [5,6], tissue engineering [7,8], joint lubrication [9,10] and other fields [11][12][13]. Poly (vinyl alcohol) (PVA) is a water-soluble polymer with excellent biocompatibility and non-toxicity.…”

Trends in Double Networks as Bioprintable and Injectable Hydrogel Scaffolds for Tissue Regeneration

“…In combination with an ionically cross-linked hyaluronic acid network, tough hydrogels (toughness of 19.6 MJ/m 3 , E = 10 MPa) were formed without any polymerization reactions being applied. 97 The necessary viscoelastic properties for printing were achieved by using high molar mass HA. The precursor solution was printed into different patterns, after which they were dehydrated, annealed at high temperature, and immersed in an FeCl 3 solution.…”

PVA‐Based Hydrogels: Promising Candidates for Articular Cartilage Repair

“…For 40 wt% PVA solution that approaches the solubility limit, devices such as autoclave sterilizer (121 °C) [ 29 ] and hydrothermal reactor (135 °C) are involved to create a high‐temperature and high‐pressure environment to facilitate the dissolution. [ 36 ] Some studies report air bubble removal by higher temperature, [ 37 ] pre‐polymerization, [ 38 ] or ultrasonic treatment [ 39 ] before further operations.…”

“…Multiple cells are cultured with GA crosslinked hydrogel and reveal no detraction in biocompatibility. [ 37–39 ] Abouzeid et al. reported a PVA hydrogel crosslinked by bifunctional cellulose nanofibers (BF‐CNF) [ 44 ] that has a similar linking mechanism to GA, specifically, crosslinking by aldehydes.…”