SYNOPSISThrough swelling experiments on polyelectrolyte (HEMA/DMA) hydrogels, pH-induced swelling kinetics is found to be best described by a diffusion-mechanical relaxation incorporated model. The theory of equilibrium swelling is quantitatively combined into the model of swelling kinetics. By doing so, the advantage is taken of applying relatively more matured knowledge of gel swelling thermodynamics to predict less knowledgeable dynamic behavior of gels.
A series of poly(sodium acrylate)/(cement clinker) [P(NaA-AA)/CC] double network (DN) hydrogel composites were prepared by solution polymerization at room temperature, using partially neutralized acrylic acid (NaA-AA) as an organic precursor and cement clinker (CC) as an inorganic precursor, redox system of potassium persulfate/sodium bisulfite (KPS/SHS) as initiator and sorbitol (Sbt) as cross-linking agent. The polymerization of organics and the hydration of inorganic substances were reflected in the temperature change curve. The FT-IR spectra and XRD demonstrated that the composite hydrogel was composed of two hydrogels network with opposite characteristic, in which one brittle, rigid silicate C-S-H hydrogel was served as the first network, and another was a soft, ductile P(NaA-AA) hydrogel as the second network. SEM observed that the inorganic components were uniformly dispersed inside the organic matrix and formed two interpenetrating structures of the composite hydrogel. Effects of CC content on swelling performance and mechanical properties of the organic-inorganic DN hydrogels were also investigated. The results show that the P(NaA-AA)/CC organic-inorganic DN hydrogel retains a certain degree of swelling capacity while also possessing a certain degree of mechanical strength. POLYM. COMPOS., 40:2462-2472, 2019
Effectively improving the mechanical properties of the hydrogel can greatly broaden its application range. The design concept of forming a double-network structure by organic-inorganic hybridization can greatly enhance the mechanical properties of traditional hydrogels. Here, a series of organic-inorganic double-network (OIDN) polyacrylamide/(sulfoaluminate cement) (PAM/SAC) composite gels by solution polymerization were synthesized at room temperature. The OIDN composite gels not only retain the characteristics of water swelling but also exhibit excellent tensile properties (stress and strain are 12 MPa and 2500%, respectively) and compressive strength (stress and strain are 65 MPa and 80%, respectively). In the preparation process, a brittle inorganic network of hydrated sulfoaluminate (hydra-SAC) and a ductile network of polyacrylamide (PAM) were formed by the manner of interpenetrating. The phase composition and thermal stability of the OIDN composite gels were characterized and determined by FTIR, XRD, SEM, and TGA, respectively. The effect of SAC on swelling and mechanical performance of the OIDN composite gels was also investigated. The results show that the use of SAC hybrid hydrogels can effectively improve the mechanical strength, and the OIDN composite gels are expected to be a potential grouting and plugging functional material.
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