Conventional concrete is generally unsuitable for underwater construction, typically requiring the addition of anti-washout admixtures (AWAs) to improve its washout resistance. Herein, we demonstrate the enhancement of cement paste washout resistance through the in-situ polymerization of acrylamide (AM) and sodium acrylate (SA) and elucidate the underlying mechanisms. Macroscopic experiments reveal a significant improvement, with washout loss reduced to 12 % and 2 % of that observed in REF at 60 min for cement pastes modified by the in-situ polymerization of AM and SA, respectively. This enhancement is attributed to the formation of a more flocculated microstructure, where smaller flocs agglomerate into larger ones due to increased floc strength induced by the bridging effect of the resultant polymers. Consequently, flocs in cement pastes with in-situ polymerized SA exhibit higher strength and a denser structure, with a fractal dimension ( D f ) exceeding 2.00, shifting the floc break mode from surface erosion to large-scale fragmentation and thereby improving washout resistance. Nevertheless, the in-situ polymerization of both AM and SA retards cement hydration, albeit through distinct mechanisms: the non-adsorbing PAM molecules primarily hinder the nucleation and formation of hydration products, whereas the adsorbed PAAS molecules predominantly inhibit the dissolution of aqueous species.
The fatal toxicity of organophosphorus nerve agents (ONAs) and the realistic condition of chemical attack occurring place trigger the urgent need to develop catalyst materials with degrading ability under the natural environment without bulk water and bases. Here, we strategically design a molecularly imprinted polymer (MIP)/MOF hybrid catalyst material by integrating enzyme-mimic MIP with Zr-MOF UiO-66-NH 2 which demonstrate promising catalytic performance for degradation of ONAs. Furthermore, sodium acrylate functions as a hydrophilic and alkaline functional unit together with pyridine-amidoxime based functional monomers (PAAO) to copolymerize into molecularly imprinted polymeric network. The basic sodium carboxylate groups were installed near the active sites to provide appropriate alkaline microenvironment, non-bulk water and acid buffer capacity for the catalysis in pure water. The resultant MIP/MOF composite catalyst demonstrate outstanding catalytic activities in both liquid and solid phase hydrolysis of ONAs. Specifically, the half-life of liquid phase hydrolysis catalyzed by MIP/UiO-66-NH 2 -0.5 achieves 9.4 min for diethyl-4-nitrophenyl phosphate (DENP) and 10 min for dimethyl 4-nitrophenyl phosphate (DMNP), and solid-state hydrolysis present rapid degradation efficiency with a half-life of 28.6 min. In addition, composite catalyst MIP-Ag/UiO-66-NH 2 -0.5 that retains substrate selectivity of MIP, enables the simultaneous degradation of two types of organophosphorus substrates (phosphate and thiophosphate) by MIP and MOF in a synergistic way. Summarily, this work displays promising potential of MIP/MOF hybrid enzyme-like catalyst as effective and practical material for the practical protection and detoxification of organophosphorus nerve agents.
危险品化学品经营许可证（带存储）