Molecular insights into the kinetic hydrate inhibition performance of Poly (N-vinyl lactam) polymers

The inhibition mechanism and the inhibition performance of four typical kinetic hydrate inhibitors (KHIs), poly (N-vinyl pyrrolidone) (PVP), poly(N-vinyl piperidone) (PVPip), poly(N-vinyl caprolactam) (PVCap) and poly(N-vinyl azacyclooctanone) (PVAco), have been studied using first-principle calculations and simulations. The results show that the inhibitors can disturb the local water structure, but also can adsorb onto the open hydrate cage, exhibiting the features of both the perturbation-inhibition and the adsorption-inhibition. By analyzing the molecular reactivity, KHI-water interactions, and adsorption ability of KHIs, it is found that the inhibition performance of the inhibitor increases with the increase of the lactam ring size, that is, PVP < PVPip < PVCap < PVAco. This study would be helpful to understand the inhibitor working mechanism as well as to promote the inhibitor screening.