Water-driven expansion of boron nitride nanosheets for self-healing tobermorite composite

The water-driven expansion of folded BNNSs on the surface of the tobermorite is studied by molecular dynamics simulation. It shows that the expansion of folded BNNSs is significantly dependent on the deterioration of water molecules on the interfacial interactions between the folded BNNSs and tobermorite and between interlayers of the folded BNNSs. The interface deteriorations allow the relative sliding between folded BNNSs and tobermorite and between interlayers of folded nanosheets. Afterward, the vibration of the monolayered BNNS induces expansion due to its flexibility. To quantify the deterioration of the adhesion between folded BNNSs and tobermorite and between interlayers of folded BNNSs, steered molecular dynamics simulations are performed to calculate the energy barrier between them. It indicates that the presence of water molecules significantly reduces the energy barrier, resulting in the release of strain energy in folded BNNSs and the expansion behavior of BNNSs. Due to the presence of water, the hydration of unhydrated cement particles occurs and releases heat. Hence, the effect of temperature on the expansion degree of BNNS is studied, which shows an acceleration in the expansion degree of BNNS and envisions the self-healing of cracks in the tobermorite composite when the temperature is increased.