Synergistic Inhibition Mechanism and Performance Enhancement of Methane Hydrate Formation by a Poly( <i>N</i> ‐vinylcaprolactam)‐Glycine Composite System

The rapid formation of methane hydrates in subsea pipelines threatens flow safety, while conventional inhibitors face environmental and efficiency limitations. This study investigates a poly(N-vinylcaprolactam)-glycine (PVCap-glycine) composite system for synergistic methane hydrate inhibition. Experimental results demonstrate superior performance: the composite system extends induction time to 672 min (135% and 37% longer than the single PVCap and glycine, respectively), reduces gas consumption by 72.6%, and lowers peak gas consumption rates by 25-45.5% compared to the blank system. Mechanistically, glycine disrupts water's hydrogen-bond network through carboxyl groups, delaying quasi-clathrate nucleation, while PVCap's hydrophobic chains adsorb on crystal nuclei, forming mass-transfer barriers. Their hydrophobic association generates composite micelles, increasing interfacial resistance by approximately 40% and elevating nucleation energy barriers. Notably, substituting glycine for partial PVCap reduces environmental burdens while achieving 135% longer induction time and 45.2% lower gas consumption than the single PVCap, overcoming the performance limitations of individual inhibitors at their optimal concentrations. The synergy originates from glycine's molecular-scale water perturbation and PVCap's interfacial regulation, coupled with wax-induced physicochemical barriers, enabling dual thermodynamic-kinetic inhibition. This synergistic strategy enables high-performance, low-environmental-impact inhibitors for deep-sea pipeline safety.