Molecular dynamics simulations on the anti-memory effect of vinyl lactam-based polymers

Molecular dynamics simulations were carried out to study the microscopic working mechanism of PVCap-co-TBA and PVCap, especially its working mechanism on the memory effect of hydrates. Our simulation results indicate that PVCap-co-TBA could weaken or even eliminate the hydrate memory effect under the higher subcooling conditions compared with PVCap. The hydrogen bonds formed by the double -bond oxygen atoms and nitrogen atoms of the lactam groups in PVCap with water molecules make the hydrate residual structures around PVCap less susceptible to decompose and provide nucleation sites for hydrate reformation at high subcooling conditions. Compared with PVCap, the introduction of strong hydrophobic tertiary butyl functional groups in PVCap-co-TBA accelerates the mass transfer of water and methane molecules, leading to the decomposition of the hydrate residual structures and the aggregation of large nano-bubble, thereby delaying the hydrate re-nucleation even at high subcooling conditions (e.g. 273 K and 30 MPa).