Qualitative degradation of the pesticide coumaphos in solution, controlled aerosol, and solid phases on quaternary ammonium fluoride polymer brushes

Abstract

With the growing demand for measurements of organophosphate (OP) pesticide use in agriculture along with the potential threat of OP‐based chemical warfare agents, there is a need for new devices or surfaces that can quickly degrade OPs into less toxic substances in a variety of environments. Using surface‐initiated atom transfer radical polymerization and post‐polymerization synthesis, we prepared a series of quaternary ammonium fluoride‐based polymer brushes designed to absorb and degrade OPs. Specifically, a polymer brush was formed using 2‐dimethylamino‐ethyl methacrylate (DMAEMA) as monomer, which, following post‐polymerization quaternization of the tertiary amine with alkylating agents and fluoride ion exchange, afforded the OP‐reactive polymer surfaces. Poly(DMAEMA) brushes were grown to thicknesses of ~100 nm on silicon wafers and glass slides and characterized by ellipsometry, atomic force microscopy, and Raman spectroscopy. Quaternization and subsequent ion exchange of the brushes were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy, respectively. The interaction of the brushes with OPs was evaluated using the OP‐based pesticide coumaphos, through the presence of the highly fluorescent degradation product chlorferon; analyzed qualitatively via fluorescence microscopy; and confirmed via nuclear magnetic resonance and mass spectrometry. We found that the fluoride form of the brush reliably degraded coumaphos deposited via controlled solution‐based applications and aerosol applications (electrohydrodynamic jetting) and from microcontact printing of the dried solid directly onto the brush. No degradation was seen for coumaphos deposited on poly(DMAEMA) or the iodide form of the quaternized brush. Copyright © 2016 John Wiley & Sons, Ltd.