Review Series on Factors Affecting Kinetic Hydrate Inhibitor (KHI) Performance. Part 1: Designing the KHI Polymer

The main active components in kinetic hydrate inhibitor (KHI) formulations are one or more key polymers. Designing the polymers to be effective requires consideration of two main topics: first, some basic structural features of the polymer need to be optimized, and second, how the polymer structure behaves in the aqueous environment under laboratory and field conditions. A review series structured into three independent parts systematically summarizes the key factors affecting KHI performance. This paper serves as the stand-alone first part of the review series, which sums up the structural features that must necessarily be considered in designing an effective KHI polymer. This review comprehensively discusses the critical structural features of KHI polymers, mainly including the amphiphilic functional groups in the repeating units, optimal polymer chain length, stereochemical configuration, functional end-capping groups, linear/branched chain structures, and monomer sequencing in copolymers. The potential inhibition mechanisms associated with the key molecular structural factors governing KHI efficacy are further clarified. The synergistic effect exhibited by these structural features enables KHI polymers to exert dual functional roles: first, perturbing the molecular behavior of the water phase, and second, adsorbing onto the surface of hydrate crystals. These combined actions collectively contribute to the kinetic inhibition of hydrate nucleation and subsequent crystal growth. This review synthesizes current understanding into a coherent framework to enable the rational design of high-performance KHIs.