Cross G H, Ren Y, Swann M J
University of Durham, Department of Physics, South Road, Durham, UK DH1 3LE.
Analyst. 2000 Dec;125(12):2173-5. doi: 10.1039/b007847f.
Thin polymeric films have been deposited as upper cladding layers on a new integrated optical interferometer fabricated from layers of silicon oxynitride on a silicon wafer. The evanescent field of the probing waveguide mode transduces refractive index changes in the polymer layer into the measured phase changes in the device. Real-time measurement of index change and its sign is obtained. Upon exposure to humid air, we record water sorption by films of poly(vinyl pyrrolidone) by a rapid positive index change for void-space filling followed by a slow negative index change for swelling. Sorption of water vapor into a thin film of the viscous liquid polymer polyethylenimine shows only swelling mode behaviour and a simple constitutive model can be applied to give the fractional water occupied volume.
薄聚合物薄膜已被沉积在由硅晶片上的氮氧化硅层制成的新型集成光学干涉仪上作为上包层。探测波导模式的倏逝场将聚合物层中的折射率变化转换为器件中测量到的相位变化。实现了折射率变化及其符号的实时测量。暴露在潮湿空气中时，我们通过聚（乙烯基吡咯烷酮）薄膜记录水吸附情况，先是由于空隙填充导致折射率快速正向变化，接着是由于溶胀导致折射率缓慢负向变化。水蒸气吸附到粘性液体聚合物聚乙烯亚胺的薄膜中仅表现出溶胀模式行为，并且可以应用一个简单的本构模型来给出水占据的体积分数。
