Hydration Behavior of Polylactam Clathrate Hydrate Inhibitors and theirSmall‐MoleculeModel Compounds

Abstract

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Comparing the Kinetic Hydrate Inhibition Performance of Linear versus Branched Polymers

“…These groups have hydrophilic parts that have strong hydrogen bonding properties such as amide, imide, or amine oxide, although many other functional groups have been investigated. − Well-known examples of KHI polymers include homo- or copolymers of N -vinyl caprolactam (VCap), N -vinylpyrrolidone (VP), and N -isopropylmethacrylamide (NIPMAm) (Figure ). The homopolymer of VCap, PVCap, is a powerful KHI and is often used as a standard to gauge the performance of other polymers . PVCap is a thermoresponsive polymer in aqueous solution, meaning that it becomes insoluble above a specific temperature. , For PVCap, this lies at about 30–45 °C depending on the polymerization method, which can affect parameters such as molecular weight, endcapping, tacticity, and branching.…”

“…The homopolymer of VCap, PVCap, is a powerful KHI and is often used as a standard to gauge the performance of other polymers. 16 PVCap is a thermoresponsive polymer in aqueous solution, meaning that it becomes insoluble above a specific temperature. 17 , 18 For PVCap, this lies at about 30–45 °C depending on the polymerization method, which can affect parameters such as molecular weight, endcapping, tacticity, and branching.…”

Attempt to Clarify the Synergistic Effect Mechanism of Clathrate Hydrate Crystal Growth Inhibitors

“…PVCap is still well known as one of the strongest KHI polymers and HCGI. PVCap is a commercially available water-soluble polymer of 7-ring N -vinyllactam. − Quaternary ammonium salts (quats) are weak KHIs yet can act as HCGIs on structure II (sII) gas hydrate. − Quats can be synergists for KHI polymers such as PVCap on both tetrahydrofuran (THF) and sII gas hydrate. − Typical quats are tetrapropylammonium bromide (TPrAB) and tetrapentylammonium bromide (TPeAB). The THF hydrate growth inhibition effect of TPeAB is stronger than that of TPrAB.…”

“…A representative KHI is a series of N -vinyllactams. The first breakthrough in KHI technology is poly­( N -vinylpyrrolidone) (PVP), which was investigated by the Colorado School of Mines (CSM) in 1991. ,− In a subsequent study, the CSM found that poly­( N -vinylcaprolactam) (PVCap) had better inhibition performance than PVP . PVCap is still well known as one of the strongest KHI polymers and HCGI.…”

Kinetic Hydrate Inhibitors─Which is Best, Block or Statistical Copolymers?

“…However, there is evidence that some polymers can melt or prevent hydrate formation indefinitely a few degrees Kelvin within the hydrate-stable region . Although many classes of chemicals have been proposed as KHIs, all commercial KHIs are based around water-soluble polymers with amphiphilic groups as the main active ingredient. − Most of these polymers are vinylic polymers, based on amide monomers including N -vinylpyrrolidone (VP), N -caprolactam (VCL), and N -isopropylmethacrylamide (NIPMAm) − (Figure ).…”