Polymeric Hydrate−Inhibitor Adsorption Measured by Neutron Scattering

• Published in: Macromolecules 2000-04, Vol.33 (7), p.2670-2679
• Main Authors: Hutter, Jeffrey L, King, H. E, Lin, Min Y
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Solution and gel properties
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma990912p

We use small-angle neutron scattering to characterize a polymeric hydrate inhibitor, poly(N-vinyl-2-pyrrolidone), adsorbed onto hydrate crystal surfaces. Gas hydrates are crystals in which water molecules encage small molecules such as propane or methane. Their stability at temperatures above the freezing point of water presents a significant challenge to oil and gas transport. Hydrate formation can be kinetically suppressed by certain polymeric inhibitors, but little is known about the mechanism of this effect. We measure a polymer coverage of 5 ± 3 mg/m2, but on only a small (2%) fraction of the available surface. Unlike the expected self-similar structure seen in other systems, this layer has the unusual property of a thickness several times the polymer coil dimension. Therefore, most of the polymer is not bound directly to the surface, suggesting the formation of surface aggregates. We speculate on the role of these aggregates in the growth inhibition of hydrate crystals.