Zucolotto Valtencir, Barbosa Neto Newton M, Rodrigues José J, Constantino Carlos J L, Zílio Sérgio C, Mendonça Cléber R, Aroca Ricardo F, Oliveira Osvaldo N
Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, CEP 13560-970, São Carlos, SP, Brazil.
J Nanosci Nanotechnol. 2004 Sep;4(7):855-60. doi: 10.1166/jnn.2004.112.
The nanoscale interactions between adjacent layers of layer-by-layer (LBL) films from poly(allylamine hydrochloride) (PAH) and azodye Brilliant Yellow (BY) have been investigated, with the films employed for optical storage and the formation of surface-relief gratings. Using Fourier transform infrared spectroscopy, we identified interactions involving SO3- groups from BY and NH+ groups from PAH. These electrostatic interactions were responsible for the slow kinetics of writing in the optical storage experiments, due to a tendency to hinder photoisomerization and the subsequent reorientation of the azochromophores. The photoinduced birefringence did not saturate after one hour of exposure to the writing laser, whereas in azopolymer films, saturation is normally reached within a few minutes. On the other hand, the presence of such interactions prevented thermal relaxation of the chromophores after the writing laser was switched off, leading to a very stable written pattern. Moreover, the nanoscale interactions promoted mass transport for photoinscription of surface-relief gratings on PAH/BY LBL films, with the azochromophores being able to drag the inert PAH chains when undergoing the trans-cis-trans photoisomerization cycles. A low level of chromophore degradation was involved in the SRG photoinscription, which was confirmed with micro-Raman and fluorescence spectroscopies.
研究了由聚（烯丙胺盐酸盐）（PAH）和偶氮染料亮黄（BY）组成的逐层（LBL）薄膜相邻层之间的纳米级相互作用，这些薄膜用于光存储和表面浮雕光栅的形成。通过傅里叶变换红外光谱，我们确定了涉及BY的SO3-基团和PAH的NH+基团的相互作用。这些静电相互作用导致了光存储实验中写入动力学缓慢，因为它们倾向于阻碍光异构化以及随后偶氮发色团的重新取向。在写入激光照射一小时后，光致双折射并未饱和，而在偶氮聚合物薄膜中，通常在几分钟内就会达到饱和。另一方面，这种相互作用的存在阻止了写入激光关闭后发色团的热弛豫，从而产生了非常稳定的写入图案。此外，纳米级相互作用促进了PAH/BY LBL薄膜上表面浮雕光栅光写入的质量传输，当偶氮发色团经历反式-顺式-反式光异构化循环时，它们能够拖动惰性的PAH链。表面浮雕光栅光写入过程中涉及少量发色团降解，这通过显微拉曼光谱和荧光光谱得到了证实。
