Abstract
We proposed a novel strategy in the fabrication of biodegradable poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) (P(AAc-co-Am)/PVA) double network (DN) hydrogels with good mechanical and self-healing properties. In the DN hydrogel system, P(AAc-co-Am) polymers form a network through the ionic coordinates between –COO– and Fe3+ and hydrogen bonding between –COOH and –CONH2, while another network is fabricated by the complexation between PVA and borax. The influences of the composition on the rheological behaviors and mechanical properties of the synthesized DN hydrogels were investigated. The rheological measurements revealed that the viscoelasticity and stiffness of the P(AAc-co-Am)/PVA DN hydrogels increase as the acrylamide and Fe3+ concentrations increase. At 0.05 mmol of Fe3+ and 50% of acrylamide, tensile strength and elongation at break of P(AAc-co-Am)/PVA DN hydrogels could reach 329.5 KPa and 12.9 mm/mm, respectively. These properties arise from the dynamic reversible bonds existed in the P(AAc-co-Am)/PVA DN hydrogels. These reversible bonds also give good self-healing properties, and the maximum self-healing efficiency of P(AAc-co-Am)/PVA DN hydrogels is up to 96.4%. The degradation test of synthesized DN hydrogels was also conducted under simulated physiological conditions and the weight loss could reach 74% in the simulated intestinal fluid. According to the results presented here, the synthesized P(AAc-co-Am)/PVA DN hydrogels have a potential application prospect in various biomedical fields.
Highlights
Hydrogels, which can swell and do not dissolve in water, are cross-linked polymer networks containing a large amount of water [1,2]
We present a simple strategy based on dynamically reversible double cross-linked networks, which can be used for the design and construction of high mechanical performances and self-healing poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) (P(AAc-co-Am)/PVA) double network hydrogels
The formation mechanism of poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) double network hydrogels are displayed in Scheme 1
Summary
Hydrogels, which can swell and do not dissolve in water, are cross-linked polymer networks containing a large amount of water [1,2]. Liu et al [17] developed a new design strategy to synthesize a dual ionic cross-linked polyethylene glycol (PEG)/poly(acrylamide-co-acrylic acid) (PAMAA) double network hydrogels, and found that the synthesized double network hydrogels can achieve high mechanical properties (stress of ~0.36 MPa and strain of ~1350%). Among these methods, the double-network strategy is considered as the effective route to synthesize high strength and toughness hydrogels. We present a simple strategy based on dynamically reversible double cross-linked networks, which can be used for the design and construction of high mechanical performances and self-healing poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) (P(AAc-co-Am)/PVA) double network hydrogels. In the poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) double network hydrogel, borate ion would form the “di-ol” complex with PVA chains to fabricate one network, and Fe3+ would form the ionic coordination interactions with poly(acrylic acid-co-acrylamide) macromolecular chains to form another network
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