Influence of ionic interactions on the photoinduced birefringence of poly[1-[4-(3-carboxy-4 hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] films.
Electrostatic interactions govern most properties of polyelectrolyte films, as in the photoinduced birefringence of azo-containing polymers. In this paper we report a systematic investigation of optical storage characteristics of cast and layer-by-layer (LbL) films of poly[1 -[4-(3-carboxy-4 hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO). Birefringence was photoinduced faster in PAZO cast films prepared at high pHs, with the characteristic writing times decreasing almost linearly with the pH in the range between 4 and 9. This was attributed to an increased free volume for the azochromophores with the enhanced electrostatic repulsion in PAZO charged to a greater extent. In contrast, in LbL films of PAZO alternated with poly(allylamine hydrochloride) (PAH), the electrostatic interactions between the oppositely charged polymers hampered photoisomerization and molecular rearrangement, thus leading to a slower writing kinetics for highly charged
Ferreira
Quirina
Q
CEFITEC, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal.
Gomes
Paulo J
PJ
Raposo
Maria
M
Giacometti
J A
JA
Oliveira
Osvaldo N
ON
Ribeiro
Paulo A
PA
D001554:Benzene / Q000737:chemistry*; D001718:Birefringence; D004563:Electrochemistry / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D015233:Models, Statistical; D036103:Nanotechnology / Q000379:methods; D010777:Photochemistry / Q000379:methods; D011137:Polystyrenes / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D055672:Static Electricity; D013997:Time Factors
D007477:Ions; D011137:Polystyrenes; C523575:poly(1-(4-(3-carboxy-4 hydroxyphenylazo)benzene sulfonamido)-1,2-ethanediyl, sodium salt); D012964:Sodium; D001554:Benzene