PNNL

Abstract

Monolayer-protected gold nanoparticle materials were synthesized and characterized for use as sorptive layers on chemical sensors. Thiols investigated as monolayer-forming molecules included dodecanethiol, benzenethiol, 4-chlorobenzenethiol, 4-bromobenzenethiol, 4-trifluoromethylbenzenethiol, 4-hydroxybenzenethiol, and 4-aminobenzenethiol. Films of selected monolayer protected manoparticle (MPN) materials were deposited on thickness shear mode (TSM) devices and vapor uptake properties were measured at 298K. Many, but not all, PMN-based sensing layers demonstrated rapid and reversible uptake of vapors, and sorptive selectivity varies with the monolayer structure. The mass of vapor sorbed per mass of sorptive material was determined and compared with sorptive polymers. Estimated partition coefficients of the MPN materials are comparable to those of polymer layers. To the extent that MPN-coated chemiresistor vapor sensors give lower detection limits than polymer-coated vapor sensors such as surface acoustic wave vapor sensors, as has been reported, such performance likely results from better signal-to-noise per sorbed vapor molecule rather than greater vapor sorption by the MPN materials.