Investigation of Methacrylic Acid at High Pressure Using Neutron Diffraction.
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.
ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford , Didcot, Oxon U.K. OX11 0QX.
William G
WG
Marshall
Department of Micro- and Nanotechnology, Technical University of Denmark , Building 345Ø, Ørsteds Plads, 2800 Kongens Lyngby, Denmark.
Andrew J
AJ
Urquhart
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde , 161 Cathedral Street, Glasgow, U.K. G4 0RE.
Iain D H
ID
Oswald
D008689:Methacrylates / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D033363:Neutron Diffraction; D044367:Phase Transition; D011312:Pressure
D008689:Methacrylates; C008384:methacrylic acid