Biodegradable MAM-based amphiphilic block copolymers: Toward efficient and eco-friendly kinetic inhibitors for methane hydrate formation

The development of low dosage hydrate inhibitors holds significant implications for the oil and gas industry. Some commercially available inhibitors, such as Luvicap EG, are derived from the lactam-containing polymer PVCap, which exhibit limited biodegradability and possess low cloud point (30-40℃), thereby constraining their practical utility. The present study successfully synthesized a series of novel amphiphilic block copolymers based on methacrylamide (MAM) by introducing biodegradable hydrophobic esters (ε-caprolactone (CL), δ-valerolactone (VL), and glycolide (GA)) onto the main chain of poly (methyl acrylamide) (PMAM), serving as KHIs. The synthesized MAM-based polymers maintain water solubility within the range of 0–98 ℃ without thermal responsiveness, effectively preventing deposition issues associated with traditional KHIs. Additionally, all MAM-based polymers demonstrated good biodegradability. The dynamics experiments have shown that PMAM homopolymers did not possess KHI effect, while the MAM-based block copolymers, especially PMAM-b-PVL, exhibited excellent performance in inhibiting hydrate nucleation. At low concentrations, the KHI effect of PMAM-b-PVL was comparable to that of the commercial KHI Luvicap EG. The in-situ Raman spectroscopy experiment further revealed the inhibition mechanism of the amphiphilic polymers, which was achieved by forming effective arrangements at the gas–liquid interface and disrupting the water structure in the interfacial region, thereby impeding the formation of hydrate cages, especially large cages. The findings provided a promising and environmentally friendly solution for the management of hydrates in the oil and gas industry