The thermal elimination of NaCl from sodium chloroacetate, a polymerization reaction that takes place between 150 and 200‡C in the solid state, leads quantitatively to the simplest polyester, polyglycolide. Byin situ IR-spectroscopy, we have shown that the reaction proceeds smoothly and directly without intermediates or by-products. The endgroups of the polymeric product — ionised carboxylate groups (-COONa) and hydrogen-bonded alcohol groups (−COH) — are clearly detectable. It is therefore concluded that the polymer forms extended chains, not rings, during the course of this solid-state reaction. That corresponds well with the idea of a polymerization reaction in the solid state. However, this experiment does not exclude the formation of polyglycolide rings as further product because they do not contain any terminating groups.
Using thermal volatilization analysis with differential condensation of volatile products, with film samples on flat-bottomed silica glass reaction tubes to permit measurements of UV spectra of partly degraded polymer, the thermal stability, the types of volatile products and the development of conjugation in the involatile residue have been compared for poly(vinyl chloride), polychloroprene, poly(vinyl acetate) and vinyl acetate/ethylene copolymers, poly(vinyl formate) and poly(vinyl alcohol). All undergo a side-group elimination reaction at lower temperatures, and polyene breakdown occurs in all the samples between 400 and 500°. The longest polyene sequences are formed by PVC. All the polymers except PVC show some complexity of products in the elimination reaction.
Authors:R. Denoyel, M. Keene, P. Llewellyn, and J. Rouquerol
The synthesis of new ordered mesoporous adsorbents, specifically of the MCM-41 type, involves a step of thermal elimination
of the template (a surfactant) where CRTA is shown to provide a 'soft chemistry' route. Once the mesoporous (i.e. 2 to 50
nm pore width) material is obtained, the pore size is determined by thermoporometry, a convenient application for low temperature
DSC. Finally, the hydrophobic - hydrophilic properties of the pore walls are explored by immersion microcalorimetry in water.
The phase stabilities of three pseudopolymorphs of DN-9693 were studied by using thermogravimetry and differential thermal
analysis. The thermal dehydration of DN-9693·2HCl·H2O proceeds by the mechanism of two-dimensional growth of nuclei. The thermal dehydration of 0.5 mol of H2O per mol of DN-9693·2HCl·2H2O, and that of 2 mol of H2O per mol of DN-9693·2HCl·3H2O, proceed by the mechanisms of three-dimensional diffusion and three-dimensional phase boundary reaction, respectively, but
the dehydration followed overlaps with the thermal elimination of HCl. The half-lives for the dehydration at 25°C show that
DN-9693·2HCl·H2O is the most stable form.
. Schlur , F. Schnell , D. Spitzer Chemical Engineering & Technology , 38 , 1477 – 1484
“ Continuous synthesis and thermalelimination of sulfinyl-route poly (p-phenylene vinylene) in consecutive flow reactions ” N. Zaquen , E