Tunable and Self-Healing Properties of Polysaccharide-Based Hydrogels through Polymer Architecture Modulation

Abstract

Hydrogel-based devices have attracted tremendous attention due to their potential applications in sensors and soft actuators. However, it is still a challenge for hydrogel-based devices to be integrated with high conductivity, sustainability, reusability, extraordinary mechanical strength, and high stretchability. Herein, a multiple-network hydrogel has been developed via a simple one-pot method based on poly­(vinyl alcohol) (PVA), Gleditsia sinensis polysaccharide gum (GSG), and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidated nanocellulose (TOCNF), using borax as a cross-linker. The optimal hydrogel (PGB-TOCNF) exhibited high mechanical strength (378 kPa), stretchability (548% breaking elongation), and compressibility (92% compression strain), as well as considerable conductive behavior. Importantly, the unique self-healing, reformable, and injectable properties of the polysaccharide-based hydrogel could be due to dynamic and reversible borate ester bonds and could also be locked by the formation of PVA nanocrystals during the freezing–thawing process. This work broadens the avenue for designing polysaccharide-derived hydrogels for applications in sensors, wearable electronics, and soft robots.

Multifunctional Conductive Double-Network Hydrogel Sensors for Multiscale Motion Detection and Temperature Monitoring

“…FT-IR tests were performed to prove the cross-linking interaction among SH, borax, and gelatin. As shown in Figures c and S2a, the characteristic peak for O–H stretching vibration of SH at 3400 cm –1 and N–H stretching vibration of gelatin at 3350 cm –1 shift to a lower wavenumber of 3300 cm –1 in SBG hydrogels, demonstrating the formation of stronger hydrogen bonds between SH and gelatin. , The appearance of a peak at 1049 cm –1 in the hydrogel is assigned to the asymmetric stretching vibration of B–O–C, confirming the generation of borate ester bonds between SH and borax. , The combination of dynamic borate ester bonds and stronger hydrogen bonds within and between each component led to the successful formation of a cross-linking network structure in SBG hydrogels. The internal morphologies of the hydrogels were characterized by SEM (Figures d and S3).…”

“…Particularly, the borax in aqueous solutions hydrolyzes into an equal portion of tetrahedral B­(OH) 4 – and trigonal planar B­(OH) 3 , which further hydrolyzes to B­(OH) 4 – . The B­(OH) 4 – then reacts with the adjacent OH of SH and gelatin to form the borate ester bonds . Therefore, the addition of borax not only improves the mechanical properties and the self-healing efficiency but also imparts conductivity to the hydrogels.…”

A Polysaccharide-Based pH-Sensitive Hybrid Hydrogel as a Sustained Release Matrix for Antimicrobial Drugs

“…Mucoadhesive hydrogels have been utilized to contact a drug release system on a specific part for targeted delivery and optimum drug release because of the affinity and span of contact . Polysaccharides have immense importance in hydrogel preparation for drug delivery applications as they are renewable, biodegradable, and cytocompatible. − ,,− However, gel strength and porosity are the controlling factors for sustained drug release application. Low-molecular-weight polysaccharides (e.g., dextrin) are not suitable because they are soluble in physiological media .…”

Novel Lignin Hydrogel Sensors with Antiswelling, Antifreezing, and Anticreep Properties

“…Flexible wearable electronic devices have attracted a significant amount of interest in the fields of human motion detection, health monitoring, electronic skins, flexible sensors, and soft robotics because of their large mechanical flexibility and their ability to adapt to different working environments to a certain extent and meet different deformation requirements. − Among a wide variety of sensing materials, hydrogels show great application potential due to their functionality, formability, and chemical editability. − Although the application value of hydrogel sensors in detecting body movement and vital signs has been proven, their practical application is still significantly limited, which is mainly caused by the inherent properties of hydrogels. − The first inherent property that hinders the practical application of hydrogels as flexible wearable electronic devices is swelling behavior. Hydrogel is a kind of soft material composed of a three-dimensional polymer framework with high water content. − For obtaining good biocompatibility, this three-dimensional polymer framework is generally designed as hydrophilic polymer segments, which will lead to the swelling behavior of the hydrogel in the aqueous environment. − Swelling behavior is usually accompanied by the introduction of a large number of solvent substances and the dilution or loss of functional molecules. − Meanwhile, the decrease of hydrogel density caused by swelling behavior also has a significant negative impact on the mechanical properties of hydrogels. − The second inherent property is the low-temperature phase transition behavior of hydrogels.…”