ISSN:
0449-2951
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Post-irradiation polymerization of γ-ray-irradiated liquid octamethylcyclotetrasiloxane containing a small amount of iodine was observed. The effect occurs at room temperature without an additional stimulus, and we conclude that it results from catalysis by HI3, i.e., a complex of HI + I2. Hydrogen triiodide is produced when iodine-octamethylcyclotetrasiloxane solutions are irradiated with γ-rays from Co60. HI3 is a good rearrangement catalyst for siloxane bonds. The dose is critical; short irradiations do not produce enough HI, while longer irradiations consume most of the I2. The triiodide complex dissociates at temperatures equal to or greater than 60°C.; thus, the polymerization stops as the temperature is raised, but contrary to usual post-irradiation polymerization processes, resumes when the sample cools. Pure irradiated octamethylcyclotetrasiloxane polymerizes upon the addition of iodine. We assume that the irradiation produces silicon-hydrogen bonds which react with iodine yielding the catalyst HI3. In all systems the HI3 was identified spectrophotometrically. However, its role in the polymerization was established directly when it was determined that an unirradiated iodine-octamethylcyclotetrasiloxane solution polymerized upon the addition of HI.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pol.1964.100020836
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