Synthesis of a novel poly-TA-Si nanohybrid with dynamic covalent SS bonds and its effect on the mechanical strength of cement paste

Using organic/inorganic nanocomposites to optimize the microstructures of cement hydration products at the micro/nanometre scale is a promising method for improving the mechanical properties of cement-based materials. One type of novel nanohybrid material modified by the flexible autonomous healing polymer poly-TA (thioctic acid) was synthesized and used as a highly efficient mechanical improvement agent for cement paste. The nanohybrids linear LNTS-1 and bulk CNTS-2 were synthesized from silane-coupled nanosilica and alpha thioctic acid. Due to the existence of hydrogen bonds, coordination bonds and dynamic covalent S S bonds, this type of linear poly-TA with a certain amount of calcium content exhibited good self-healing properties. Linear LNTS-1 can effectively improve the macro flexural strength of cement-based materials without a negative effect on their compressive strength. The flexural strength of cement pastes with 1.0‰ LNTS-1 increased by 11.9%, 15.6%, and 16.9% after curing for 3, 7, and 28 d compared with the control cement paste. The results of adsorption experiments show that nanohybrid LNTS-1 has strong adsorption on calcium ions, which affects the formation of cement hydration products.