ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Anthryl groups bound to various polyesters and polyesterurethanes as side groups were photodimerized in solid state in a nitrogen atmosphere. The rate of photodimerization is strongly affected by polymer structure as observed in the photodimerization of dilute solutions. The results revealed the importance of segment mobility rather than local concentration of anthryl groups. Temperature effects on the rate of photodimerization indicated that the rate jumped above the glass transition temperature (Tg). A definite difference in photodimerization behavior was apparent between polyesters and polyesterurethanes. Anthryl groups in polyesters were to some extent photodimerized at Tg, whereas polyesterurethanes did not react at all. Hydrogen bonding in polyesterurethanes restricted the movement of anthryl groups and consequently additional energy was required to liberate them and allow photodimerization to proceed. The anthryl groups can be recovered from the photodimerized polymers by heating to 80-100°C. The activation energy of thermal dissociation of the photodimer depends to a great extent on polymer structure. These results were interpreted as being due to the strain brought about by photodimer formation exhibited this dependence. The photodimerization-thermal dissociation cycle was reversible (reversibility: 95-100% under nitrogen). A novel principle of reversible photomemory, based on dry unit processes that consisted of image recording above Tg, fixation of image by cooling below Tg, and image erasure at elevated temperature, was proposed.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1978.170161101
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