In this work, poly(vinyl alcohol) (PVA) was incorporated into the networks of polyacrylamide/polyacrylic acid (PAM/PAA) to prepare novel PAM/PAA/PVA Triple-network (TN) hydrogels by an in situ polymerization and repeated freezing-thawing (F-T) process. The TN hydrogels have not only high mechanical strength, but also a moderate swelling ability by varying the weight ratio of calcium chloride (CaCl 2 ) and PVA and free shaping. The compressive stress of the as-prepared hydrogels could reach 11 MPa, and the highest stretching stress could reach 0.8 MPa. Upon mechanical loading, the coordination network between PAA and CaCl 2 served as sacrificial bonds to efficiently dissipate energy. However, they can reform when the mechanical load is released, resulting from the fast coordination between PAA and Ca 2+ . Therefore, TN hydrogels have potential application in biomaterials.Scheme 1 Preparation of TN gels by using one-pot, two step method.6790 | RSC Adv., 2018, 8, 6789-6797This journal is
Abstract.A novel post-crosslinking method by heating the composite polymer with dispersed reactive microgels was used to prepare microgel composite (MC) hydrogels. This MC hydrogels were crosslinked by reactive microgels instead of traditional crosslinkers. The reactive microgels contained hydroxymethyl groups, which acted as post-crosslinkers. They were prepared by inverse emulsion polymerization. The formed MC hydrogels at appropriate conditions had high equilibrium swelling ratio and excellent mechanical properties. The heating conditions and the polymer water content influenced the hydrogel properties. For MC hydrogels prepared by direct heating the as-prepared composite polymers with 75% water content, their properties were influenced by heating conditions. When the heating conditions were 90°C for 4 h, the MC hydrogel had a tensile strength of 32 kPa and a high elongation of 960%. In addition, for MC hydrogels prepared by heating the partly evaporated composite polymers, their properties can be adjusted by the polymer water content. Appropriate reduction of the polymer water content was beneficial to improve the mechanical strength of the MC hydrogels. The appropriate polymer water content was important to prepare MC hydrogels with excellent mechanical properties. When the composite polymer with 50% water content was heated at 90°C for 3 h, the MC hydrogel had high tensile strength of 130 kPa and high tensile elongation of 503%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.