Pressure-induced polymorphism of caprolactam : a neutron diffraction study
Hutchison, Ian and Bull, Craig L. and Marshall, William G. and Urquhart, Andrew J. and Oswald, Iain D.H. (2019) Pressure-induced polymorphism of caprolactam : a neutron diffraction study. Molecules, 24 (11). 2174. ISSN 1420-3049 (https://doi.org/10.3390/molecules24112174)
Preview |
Text.
Filename: Hutchison_etal_Molecules_2019_Pressure_induced_polymorphism_of_caprolactam.pdf
Final Published Version License: Download (6MB)| Preview |
Abstract
Caprolactam, a precursor to nylon-6 has been investigated as part of our studies into the polymerization of materials at high pressure. Single-crystal X-ray and neutron powder diffraction data have been used to explore the high-pressure phase behavior of caprolactam and we have observed two new high pressure solid forms. The transition between each of the forms requires a substantial rearrangement of the molecules and we observe that the kinetic barrier to the conversion can aid retention of phases beyond their region of stability. Form II of caprolactam shows a small pressure region of stability between 0.5 and 0.9 GPa with Form III being stable from 0.9 GPa to 5.4 GPa. The two high-pressure forms have a catemeric hydrogen-bonding pattern compared with the dimer interaction observed in the ambient pressure Form I. The interaction between the chains has a marked effect on the directions of maximal compressibility in the structure. Neither of the high-pressure forms can be recovered to ambient pressure and there is no evidence of any polymerization occurring.
-
-
Item type: Article ID code: 68317 Dates: DateEvent10 June 2019Published1 June 2019Accepted3 May 2019SubmittedSubjects: Science > Chemistry
Medicine > Therapeutics. PharmacologyDepartment: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences Depositing user: Pure Administrator Date deposited: 10 Jun 2019 09:06 Last modified: 19 Mar 2024 02:38 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/68317