ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Monolayers of the photochromic hairy-rod type polymers poly(5-[2-[4-(4-hexylphenylazo)-phenoxy]ethyl]-L-glutamate) (1) and poly(5-(2-[4-(4-decyloxyphenylazo)phenoxy]ethyl)-L-glutamate) (2) were investigated at the air/water interface. At constant surface pressure the monolayers of the polymers exhibit a reversible expansion upon irradiation with ultraviolet (UV)-light, due to the photoinduced E-Z-isomerization of the azobenzene chromophore and a concomitant restructuring of the monolayer. The area increase is lower than expected from the isotherms of monolayers spread from irradiated and non-irradiated solutions. This can be attributed to a hindrance of photoisomerization, as proved by UV/Vis spectroscopic investigations. The hindrance of photoisomerization, and the photomechanical effect depend on temperature, surface pressure and the nature of the polymer, which all influence the flexibility of the monolayer. From a comparison of the isomerization rate and the rate of the photomechanical effect a two-step mechanism for the monolayer restructuring is deduced.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1994.021951201
Permalink