Multilayer method as a tool for depth dependent polymer film photodegradation studies

A new polymer film destructive depth profiling protocol is presented for th e analysis of photo- and thermally degraded thin films on the depth scale o f less than 100 microns. The method, demonstrated here on thin films of pol y(vinyl chloride) (PVC), provides a means of preparation of thin laminates of high optical quality comprised of many (>20) thin layers of individual t hickness less than 15 microns. The constituent layers are fused together un der appropriate pressure, temperature and time treatment to yield a film as sembly of high optical quality that behaves like a uniform single layer dur ing photodegradation exposure, but which may still be separated after treat ment. Compared to previous techniques, this new method is relatively simple and non-labor intensive. Film adhesive properties are controlled to within +/-5% Concentration depth profiles of polymer photolysis products were rec onstructed by analyzing each of the separated layers using UV-visible spect rophotometry. The continuity of these film assemblies with respect to mecha nical properties, adhesive properties and the depth distribution of key pho tolysis reagents and products was confirmed using photothermal and referenc e microscopy techniques. Optical absorption depth profiles examined in UV- photodegraded poly(vinyl chloride) (PVC) films exhibited the classic depend encies expected in the presence of nitrogen and oxygen atmospheres.