Hydrogen-Bond Acidic Hyperbranched Polymers for Surface Acoustic Wave (SAW) Sensors

A series of novel hyperbranched hydrogen-bond acidic polymers for surface acoustic wave (SAW) sensor applications were prepared by functionalizing hyperbranched polycarbosiloxanes or polycarbosilanes with phenol or hexafluoro-2-propanol groups. Starting polymer, sensor polymer, and reagent structures were confirmed by IR, 1H, 13C, and 29Si NMR, SEC, or GCMS as appropriate. The hyperbranched sensor polymers were coated onto 500 MHz SAW platforms and their responses to the nerve agent simulant dimethyl methylphosphonate (DMMP) were studied. The hyperbranched sensor polymers with phenol groups gave very high initial responses to DMMP which dropped to 30% of the initial levels over a period of 6 months, and the hyperbranched sensor polymers with hexafluoro-2-propanol groups gave lower initial responses that did not change with time. Hence, the long-term performances of hyperbranched phenolic sensor polymers and hyperbranched hexafluoro-2-propanol sensor polymers were found to be comparable.