Investigation of methacrylic acid at high pressure using neutron diffraction

William G. Marshall, Andrew J. Urquhart, Iain D.H. Oswald

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Abstract

This article shows that pressure can be a low-intensity route to the synthesis of polymethacrylic acid. The exploration of perdeuterated methacrylic acid at high pressure using neutron diffraction reveals that methacrylic acid exhibits two polymorphic phase transformations at relatively low pressures. The first is observed at 0.39 GPa, where both phases were observed simultaneously and confirm our previous observations. This transition is followed by a second transition at 1.2 GPa to a new polymorph that is characterized for the first time. On increasing pressure, the diffraction pattern of phase III deteriorates significantly. On decompression phase III persists to 0.54 GPa before transformation to the ambient pressure phase. There is significant loss of signal after decompression, signifying that there has been a loss of material through polymerization. The orientation of the molecules in phase III provides insight into the possible polymerization reaction.

Original languageEnglish
Pages (from-to)12147-12154
Number of pages8
JournalJournal of Physical Chemistry B
Volume119
Issue number36
Early online date19 Aug 2015
DOIs
Publication statusPublished - 10 Sep 2015

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Keywords

  • polymerization
  • ambient pressures
  • decompression phase
  • loss-of-signal
  • low-intensity
  • methacrylic acids
  • polymerization reaction
  • polymethacrylic acid
  • polymorphic phase transformations
  • neutron diffraction

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