Time of flight secondary ion mass spectrometry and electron spectroscopy for chemical analysis of commercial hydrogels and model amphiphilic polymers using cryogenic sample handling techniques

A sample handling protocol at cryogenic temperatures was developed for Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Electron Spectroscopy for Chemical Analysis (ESCA) that enabled the surface analysis of polymer systems in the hydrated (frozen) state.; This protocol was applied to the analysis of commercial hydrogel contact lens materials using ToF-SIMS and ESCA. These methods detected changes in surface chemistry between the hydrated (frozen) and dehydrated surfaces. Analysis of the hydrated surfaces detected polymer components indicative of the commercial formulation as well as ice clusters. Analysis of the dehydrated materials detected changes in surface chemistry relative to the hydrated surface in addition to loss of water due to sample dehydration.; ToF-SIMS analysis of a series of seven poly (allyl methacrylate-g-dimethylsiloxane), AMA-g-DMS, graft copolymers in the hydrated state revealed high mass oligomeric ion distributions for systems with bulk PDMS content greater than 25 weight percent. This marks the first time that detection of high mass oligomeric ion distributions from hydrated (frozen) surfaces has been reported. Analysis of the dehydrated surface detected formation of high mass oligomeric ion distributions for systems with PDMS bulk content greater than 15 weight percent. No direct correlation between the PDMS graft length and formation of these high mass olilgomeric ion distributions could be made. This work will aid in the understanding of the structural differences in graft copolymers between the hydrated and dehydrated surfaces.