Pressure dependence of thickness and refractive index of thin PMMA-films investigated by surface plasmon and optical waveguide spectroscopy

Abstract

SUMMARY: Total internal reflection (TIR) and attenuated total reflection (ATR) measurements in the Kretschmann configuration have been performed at 25 8C with poly(methyl methacrylate) (PMMA) films (of ca. 2.5 lm thickness) spincoated on top of a 50 nm thick gold layer, as a function of the applied hydrostatic pressure, ranging from p = 1 N 10 5 to 1 050 N 10 5 Pa. The analysis of guided optical modes allows for the separate determination of the refractive index n and the thickness d of the polymer films as a function of pressure. The pressure media in contact with the PMMA films were water, ethanol, and methanol. Thermodynamic theories for the density of solids and fluids in combination with the Lorentz-Lorenz equation for their optical properties fit the experimental data quite well.

Functional Thin Polymer Films at High Pressure

“…Both shifts can be perfectly fitted by only considering the separately measured refractive index of H 2 O (which agreed well with literature values) and assuming that the Au optical data (e 0 , e 00 , d) remained constant within this pressure range. [2] It is also important to note that the whole substrate configuration remained stable even after repeated pressure cycling in water to high pressures and back, as well as, during the CV experiments.…”

“…[2] The instrument, hence, allows for the experimental investigation of various thinfilm samples and their structural and functional properties as they vary upon changing the applied temperature and pressure. Reported examples include the pressure dependence of glass transition temperatures of a series of polymer films [3] or the collapse (and re-swelling) behavior of surface-grafted polymer gels.…”

Synthesis and characterization of thioether-containing polyimides with high refractive indices

“…In this paper, we utilized a prism coupler instrument madein-house to measure the refractive indices of the resulting PI films by the ATR method. It is well known that the ATR method is often used to measure the refractive indices of polymer films, and that its measurement sensitivity is <10 −3 [29][30][31][49][50][51][52][53][54][55]. In order to determine the accuracy of our instrument, the PI (Ref-PI-a) made from PMDA and ODAwas selected as a standard material.…”

Electrochemical surface plasmon spectroscopy—Recent developments and applications

“…The effect of pressure on the optical and electrical properties of polymers used in electronic devices and sensors is very valuable for the further understanding of electronic phenomena [35]. There have been only limited pressure studies involving these problems [36][37][38][39][40][41]. Therefore, high-pressure ESPR experiments are potentially useful to gain insights into the relationships between charge transport and structure in thin films of conducting polymers, particularly the characterization of electrode surfaces covered with adsorbed molecules or polymers is a field with a wide range of research opportunities.…”