Chemical analysis of functionalized polymer surfaces

Abstract

Over the last 40 years we have witnessed an impressive development of the tools for the analysis of polymer surfaces. However, there still are questions, which are very challenging and the quest of answering these questions means working at the frontier of current science. We discuss some general features of the surfaces of synthetic polymeric materials and the new features formed in surface treatments. It is extremely difficult and in many cases virtually impossible to determine the concentration of all the chemical species present in such complex materials. The determination of their vertical distribution, i.e. the depth profile of these concentrations, is even more complicated. A new situation has arose since more and more surface functionalization techniques have gone from the laboratory to the production line. Microarrays are a good example. The quality control of the production is a challenging and sometimes expensive task.The combination of surface chemical reactions with instrumental techniques has been proven to be a valuable tool for surface analysis. After discussing some recent progress in that field we present examples that demonstrate a continuous progress in that field. The fluorescence dye Fluram can be used to determine the concentration of NH 2 groups at a surface and their local density. Nitric oxide can be used to determine radicals in polymer surfaces, also in the presence of oxygen. The trifluoroacetic anhydride (TFAA) derivatization of hydroxyl groups provides reliable data. The diffusion of fluoresceine isothiocyanate (FITC) labelled globuline was used to characterize the network density of surface coupled hydrogels.

Critical remarks on chemical derivatization analysis of plasma‐treated polymer surfaces and plasma polymers

“…Another important derivatization reagent which has frequently been used for XPS analysis of oxygenated or nitrogenated polymer surfaces is trifluoroacetic anhydride (TFAA), generally supposed to form trifluoroacetate esters with hydroxy groups and trifluoroacetamides with secondary and primary amino groups . The dominant opinion today is that TFAA reacts exclusively with XH moieties, X = O, N; other reaction possibilities of TFAA were mostly neglected (see below, chapter 2.5, for an exception).…”

Post‐Synthetic Modification of ZIF‐8 Crystals and Films through UV Light Photoirradiation: Impact on the Physicochemical Behavior of the MOF

“…It is difficult to distinguish some nitrogen species because they do not present a significant difference in their chemical shifts of N 1s . In our case the BE was located at 399.1 eV which was at similar position to that of neutral imine nitrogen atoms, whereas if an oxime group were present the signal should be above 400.0 eV . All the results found both by FTIR and XPS indicates that these species are terminal surface imine‐type groups disconnected from the structure of the ZIF‐8.…”

Why do we need chemical derivatization?

“…Some years ago, Stefan Kröpke, Falko Pippig, and I wrote a paper on the status of the chemical analysis of functionalized polymer surfaces . We started by describing what we actually have to deal with.…”