The Macro Self-Assembly Study Of Tough Polyacrylamide Hydrogels

Hydrogels were used such as biomedical, catalysis, sensors et al. fields due to comprise a considerable amount of water, good elasticity and good biocompatibility. However, the poor mechanical property significantly limited the application range of hydrogels. Therefore, many scholars were devoted to synthetize the tough hydrogels. But with the application of hydrogels changed more and more widely, improving the mechanical property of hydrogels merely was not satisfied with the actual use requirements. Therefore, it was important to prepare the intelligent tough hydrogels.The slide-ring hydrogels, double network hydrogels, organic–inorganic nano-composite gels, macromolecular microsphere composite hydrogels, multiarmed hydrogels and hydrophobic association hydrogels were had the excellent mechanical property. However, these hydrogels disrupted facilely along the cracks and the strength decreases rapidly if there was a little notch or flaw in the bulk. As a result, the notch sensitivity of hydrogels obviously reduced their sustainability and reliability in the practical applications. In this paper, we were synthetized the highly stretchable and notch-insensitive hydrophobic association hydrogels by redox initiation systems. The hydrogels were prepared by free radical copolymerization of acrylamide(AAm) and hydrophobic vinyl groups. The dynamic crosslinking points of the hydrogels were attributed to the combined effects of hydrophobic association and metal ion coordination. As a result, the tensile stress of hydrogels could reach 675 KPa and had the excellent notch-insensitive property.The application range of hydrogels was widened by investigating the tough hydrogels. However, most of tough hydrogels didn't have the adhesive property. They couldn't adhesive with other hydrogels or materials. In some special applications of biomedical, there were required the hydrogels were able to adhesive with other hydrogels or materials. Up to now, there were some adhesive hydrogels were applied in biomedical. But the mechanical property of these adhesive hydrogels was poor, this made the service life of hydrogel change shorter. So it is very important to prepare the tough adhesive hydrogels. In this paper, we prepared the polyacrylamide(PAAm) and polyacrylic acid(PAAc) hydrogel respectively. Both of the PAAm and PAAc hydrogels didn't exhibit the self-healing behavior after the sample was cut. When PAAm and PAAc samples were touched each other for a few seconds, however, the PAAm hydrogels exhibited a strong adhesive characterization with PAAc hydrogels via hydrogen bonds which formed by molecular self-assembly. Moreover, some hydrophobic groups were introduced into PAAm and PAAc hydrogels for enhancing the mechanical properties.