Pressure Induced Topochemical Polymerizationof Solid Acryalmide Facilitated by Anisotropic Response of Hydrogen Bond Network

Abstract

<p>The pressure induced polymerization of molecular</p> <p>solids is an appealing route to obtain pure,</p> <p>crystalline polymers without the need for radical</p> <p>initiators. Here, we report a detailed density</p> <p>functional theory (DFT) based study of the</p> <p>structural and chemical changes that occur in</p> <p>defect free solid acrylamide, a hydrogen bonded</p> <p>crystal, when it is subjected to hydrostatic pressures.</p> <p>Our calculations predict a polymerization</p> <p>pressure of 94 GPa, in contrast to experimental</p> <p>estimates of 17 GPa, while being able</p> <p>to reproduce the experimentally measured pressure</p> <p>dependent spectroscopic features. Interestingly,</p> <p>we find that the two-dimensional hydrogen</p> <p>bond network templates a topochemical</p> <p>polymerization by aligning the atoms through</p> <p>an anisotropic response at low pressures. This</p> <p>results not only in conventional C-C, but also</p> <p>unusual C-O polymeric linkages, as well as a</p> <p>new hydrogen bonded framework, with both NH...</p> <p>O and C-H...O bonds.</p>