Ferreira Quirina, Gomes Paulo J, Raposo Maria, Giacometti J A, Oliveira Osvaldo N, Ribeiro Paulo A
CEFITEC, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal.
J Nanosci Nanotechnol. 2007 Aug;7(8):2659-66. doi: 10.1166/jnn.2007.621.
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
静电相互作用决定了聚电解质薄膜的大多数性质，就像含偶氮聚合物的光致双折射那样。在本文中，我们报告了对聚1 - [4 - (3 - 羧基 - 4 - 羟基苯偶氮)苯磺酰胺基]-1,2 - 乙二基，钠盐的流延膜和层层组装(LbL)膜的光存储特性的系统研究。在高pH值下制备的PAZO流延膜中，双折射的光致诱导更快，在4到9的范围内，特征写入时间几乎随pH值呈线性下降。这归因于在更高程度带电的PAZO中，随着静电排斥增强，偶氮发色团的自由体积增加。相比之下，在PAZO与聚(烯丙胺盐酸盐)(PAH)交替的LbL膜中，带相反电荷的聚合物之间的静电相互作用阻碍了光异构化和分子重排，从而导致高电荷状态下较慢的写入动力学。
