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Self‐assembled multilayers of photochromic bola‐amphiphile and ionene‐type oligomer: Relation of aggregate state and photoisomerization
Author(s) -
Park AeLi,
Hong JongDai
Publication year - 1999
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19991420113
Subject(s) - photoisomerization , azobenzene , photochromism , chromophore , isomerization , oligomer , materials science , photochemistry , polymer chemistry , azo compound , irradiation , polymer , chemistry , organic chemistry , physics , composite material , nuclear physics , catalysis
Photoisomerization process of azobenzene has been studied in the multilayer assemblies of poly(vinylsulfate, potassium salt) and two different layer‐elements; 4,4′‐azobenzene‐bis(12‐trimethylammonium‐N‐yl dodecyloxy) dibromide (BA‐12, 1) and an ionene oligomer, poly(4,4′‐azobenzene‐bis(12‐dimethyl‐ammonium‐N‐yl dodecyloxy) bromide) (PAZ‐12, 2 ). The change of the photoactive layers from BA‐12 to PAZ‐12 was found to dramatically influence the photoisomerization characteristics of the azobenzene in the multilayer. Surprisingly, we have observed that the chromophore interaction in PAZ‐12 is stronger than that in BA‐12 in self‐assembled (SA) film (λ max = 320 nm compared to 341 nm), although the aggregate formation is considered to be hindered by the strains of the polymer chains. For BA‐12/PVS and PAZ‐12/PVS multilayers, the steady state between cis and trans isomers reached after ca 20 min. and 48 min. of UV irradiation, respectively. It was also found that after first one trans‐cis‐trans cycle of the photoisomerization, the trans to cis isomerization was completed in 30 sec of irradiation in the following 10 cycles without appearance of any fatigue in the multilayer film.