Molecular recognition on acoustic wave devices: Sorption in chemically anchored zeolite monolayers
- Purdue Univ., Lafayette, IN (United States)
Zeolite crystals were attached to the gold electrodes of quartz crystal microbalances (QCM). Monolayers of thiol-alkoxysilanes on the gold surface served as interfacial layers for the subsequent adhesion of the zeolite crystals to the QCM. The process of anchoring the zeolite crystals via the thiol-silane monolayers was studied by reflection adsorption infrared (IR) spectroscopy, contact angle, and scanning electron microscopy (SEM). The siloxane linkages between the microporous zeolite crystals and the terminal cross-linked polysiloxane groups of the interfacial monolayer play an important role in enhancing the packing density of microporous crystals and the thermal stability (up to at least 350 {degrees}C) of the film on the gold surface. Dynamic sorption isotherms of organic vapors and nitrogen as well as the transient sorption behavior of organic vapor pulses were studied to characterize the zeolite-coated QCMs. The resonance frequency response of zeolite-coated QCMs to vapor pulses could be increased up to 500-fold compared to the bare sensor. The regular micropores (0.3-0.75 nm) of the QCM-attached zeolite crystals were found to efficiently control molecular access into the coating. Selectivity of the frequency response in excess of 100:1 toward molecules of different size and/or shape could be demonstrated. The kinetics of vapor desorption from the zeolite layers are strongly dependent on the adsorbate/zeolite combination, thus providing an additional capability for molecular recognition. 33 refs., 11 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 563416
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 23 Vol. 96; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
Similar Records
Monomolecular layers and thin films of silane coupling agents by vapor-phase adsorption on oxidized aluminum
Molecular Anchors for Self-Assembled Monolayers on ZnO: A Direct Comparison of the Thiol and Phosphic Acid Moieties