Reactivity of free radical intermediates that form spontaneously during molecular chlorine action on acetylene and vinyl monomers at low temperatures

Abstract

In this study ESR, UV, VIS and IR spectroscopy, chromatography, calorimetry, and elemental analysis were employed to show the spontaneous formation of free radicals under low-temperature action of molecular chlorine on acetylene monomer p-diethynylbenzene, and vinyl monomer acrylamide. These radicals are able to initiate chain reaction of polymerization of monomers at low temperatures. This reaction results in a completely soluble polymer with a yield of 25 %, while an insoluble cross-linked polymer has been obtained during polymerization of p-diethynylbenzene initiated by other means. For example, under radiolysis by 1000 kGy the soluble fraction of obtained polymer was ≈ 1% while the overall yield was ≈ 10%. p-Diethynylbenzene polymerizes at temperatures close to chlorine melting (170 K). Polymerization of acrylamide takes place in the temperature range of 180–210 K with an yield of polymer ≈ 10%. The low-temperature chlorination of a 20%-solution of acrylamide in glycerol enables a twofold increase of the polymer yield, and a tenfold decrease of the chlorine content in it.