The Fabrication And Characterization Of Double Network Hydrogel

Hydrogel, as a kind of high water-content soft material with three-dimensional network, has great potential applications in biological tissue engineering fields.However, the traditional hydrogel is often brittle and has limited elongation.Therefore, hydrogel has only been applied in the areas such as drug release and cell culture where the mechanical properties are not demanding, which extensively limits its application in load-bearing fields. Other interesting properties of hydrogels such as shape memory effects also have potential application in sensing and actuating devices. Therefore, it is necessary to study the high mechanical strength and shape memory properties of hydrogels.DN gel as a kind of hydrogel with high mechanical strength, its brittle and rigid first network and the soft and tough second network endows the hydrogel with excellent mechanical properties. Therefore, the focus of this paper is to develop double-network hydrogels with high mechanical strength and shape memory properties. The main contents are divided into the following parts:(1) In this paper, we synthesized a PDAC-PEG/P(AAm-co-AAc) double-network hydrogel with high mechanical strength and shape memory properties. Among them,neutral polyethylene glycol (PEG) was the rigid and brittle first network, and polyacrylloxyethyl trimethyl ammonium chloride (PDAC) as a molecular stent was embedded in the first network. The copolymer of acrylamide and acrylic acid(P(AAm-co-AAc)) was the soft and tough second network. In this way,double-network hydrogel with excellent tensile properties was successfully prepared.Compared to those DN hydrogels, of which the second network are neutral constituents, acrylic acid as an electrolyte was introduced into the second network of the hydrogel, which broadening the application range of double-network hydrogel.And the double-network hydrogel is imparted with redox-induced shape memory properties based on the complexation between the carboxyl group of the acrylic acid and Fe3+.(2) This paper reports a gelatin-reinforced gelatin/polyacrylamide double-network hydrogel which was prepared by one-pot method. In the hydrogel, the physical crosslinked gelatin (Gelatin) was the first network and the second network was polyacrylamide (PAAm). The prepared gel shows excellent tensile and compression performance. In this paper, we investigated the effects of gelatin content, acrylamide concentration and crosslinker concentration on the tensile properties of DN gels, and study the hysteresis and recovery properties of the hydrogels. One-pot preparation of double-network hydrogels simplifies the preparation process of DN gels and also extends the application of double-network concepts.