Phase transition temperature controllable poly(acrylamide-<Emphasis Type="Italic">co</Emphasis>-acrylic acid) nanocomposite physical hydrogels with high strength |
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Authors: | Li-qin Zhang Li-wen Chen Ming Zhong Fu-kuan Shi Xiao-ying Liu Xu-ming Xie |
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Institution: | Laboratory of Advanced Materials(MOE), Department of Chemical Engineering,Tsinghua University, Beijing 100084, China |
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Abstract: | Poly(acrylamide-co-acrylic acid) nanocomposite physical (P(AAm-co-AAc)NCP) hydrogels have been prepared through the in situ free radical solution polymerization based on a “single network, dual cross-linkings” strategy. The P(AAm-co-AAc) NCP hydrogels are composed of nanobrushes of P(AAm-co-AAc) chains grafted on the surface of vinylhybrid silica nanoparticles (VSNPs). In the hydrogel system, the VSNPs act as the “analogous chemical cross-linking points” once the hydrogen bonds formed between the P(AAm-co-AAc) chains of the nanobrushes, thus leading to the fabrication of high-strength P(AAm-co-AAc) NCP hydrogels. Compared with conventional thermosensitive P(AAm-co-AAc) hydrogels, the P(AAm-co-AAc) NCP hydrogels have a broader range of phase transition temperature, which can be adjusted by altering the monomer ratio, the VSNPs concentration, the addition of urea and N,N-dimethylacrylamide (DMAAm). At the same time, the mechanical properties of the P(AAm-co-AAc) NCP hydrogels have been improved significantly by the introduction of VSNPs. Furthermore, both the phase transition and the tensile strength of the P(AAm-co-AAc) NCP hydrogels are largely influenced when Fe3+ ions are introduced as the ionic crosslinkers into the hydrogel networks. |
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Keywords: | Poly(acrylamide-co-acrylic acid) Nanocomposite physical hydrogels Phase transition High strength |
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