Mechanical Strengths of Hydrogels of Poly(N,N‐Dimethylacrylamide)/Alginate with IPN and of Poly(N,N‐Dimethylacrylamide)/Chitosan with Semi‐IPN Microstructures

Abstract

Tough hydrogels receive continuous attention because of their promising applications in many fields. Herein, tough hydrogels of poly (N,N‐dimethylacrylamide) (PDMAA)/alginate (SA) are prepared, with interpenetrating network (IPN) and of PDMAA/chitosan (CS) with semi‐IPN microstructure, respectively. The toughening of the hydrogel by incorporating natural polymers is studied by compressing tests and dynamic mechanical analyses. Moreover, cyclic load–unload compressing of the two types of hydrogels are performed at low strains and under relatively high strains, in order to compare their strength and anti‐fatigue properties. The results indicate that the mechanical strength can be markedly improved upon addition of the natural polymers, and the IPN hydrogel of PDMAA/SA reveals much higher mechanical performances but is less stable. However, the semi‐IPN hydrogel of PDMAA/CS displays excellent anti‐fatigue stability, but with relatively low strength. Swelling tests, scanning electron microscopy, and Fourier transform infrared spectroscopy are carried out to study the microstructures of the hydrogels, which are carefully analyzed to understand the difference in mechanical performances of those hydrogels. The results suggest that the presence of sacrificial unit and higher chain density in the IPN are helpful for toughening hydrogels, while the semi‐IPN network is beneficial to improve the energy dissipation efficiency.

Self-Healing Hydrogel Scaffolds through PET-RAFT Polymerization in Cellular Environment

“…In order to obtain hydrogel scaffolds relevant for cell encapsulation, all monomers selected for this project were polymerized directly in PBS, using the cytocompatible EY as a catalyst and 4-cyano-4-{[(ethylthio)carbonothioyl]thio}pentanoic acid (CEPA) as the chain transfer agent (CTA) (Figure ). A range of commercially available (meth)acrylate and acrylamide monomers, i.e., poly(ethylene glycol) diacrylate (PEGDA), poly(ethylene glycol) methacrylate (PEGMA), N , N -dimethylacrylamide (DMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and N , N -methylene-bis-acrylamide (NMBA) were selected for investigation for their water solubility and their reported ability to form crosslinked networks. − Polymerizations were carried out inside a plastic syringe, using a typical photoreactor setup for PET-RAFT (Figure S1). All polymerizations were carried on for 60 min to ensure full gelation was achieved.…”

Reinforcement of Self‐Healing Polyacrylic Acid Hydrogel with Acrylamide Modified Microcrystalline Cellulose†

“…Therefore, improving the mechanical performances of hydrogel is becoming one of the foci of the related researches. Lately, a series of high strength hydrogels have been successfully developed, like fiber enhanced hydrogel, nano/macro particles enhanced hydrogel, interpenetrating network hydrogel and double network hydrogel . In spite of the improved mechanical strength, those hydrogels usually lack self‐healing ability, while un‐reversible breaking during stress would limit their stability and long‐term applications [1c,4,7] …”

Systematic Evaluation of a Novel Self-Healing Poly(acrylamide-co-vinyl acetate)/Alginate Polymer Gel for Fluid Flow Control in High Temperature and High Salinity Reservoirs

“…Alginate is one of the more widely used natural ingredients for drug delivery through IPNs using natural polysaccharides. Alginate is hydrocolloid in the form of a linear copolymer of linked α-L-gulopyranuronic acid (G monosaccharides) and β-D-mannopyranuronic acid (M monosaccharides) [15]. Alginate was selected due to its inherent capability for ionic crosslinking through high transient calcium-carboxyl complexation, which allows for reversible energy dissipation by dissociation/reassociation [16].…”