A synchrotron infrared absorption study of pressure induced polymerization of acrylamide.

The hydrogen bonded dimeric structure of the model amide based molecular crystal acrylamide has been investigated under pressure using micro-spectroscopy, employing synchrotron infrared radiation up to 24GPa at room temperature. The high pressure spectra indicate systematic evolution of new features above 4GPa, which have been identified to be due to the emergence of a polymeric phase. The polymerization gets completed up to 16.8GPa and the observed changes are found to be irreversible upon the release of pressure. The behavior of NH stretching modes indicate that the uniform inter- and intra-dimeric interactions, rather than depicting a drastic reconstruction across the phase transition, show subtle modifications and become diverse in the high pressure polymeric phase.