Interfacial recognition and adsorption processes
The design and function of receptors for molecular recognition is of vital importance for the construction of novel sensors. Initially the project has investigated the relationship between the shape of the active site of the receptor and its sensitivity and selectivity for analytes in solution. The techniques of electrochemistry, NMR and molecular modelling have been used to study materials interactions. An optimum receptor design was established for a range of analytes so that the surface of an electrode could be modified to create an analytical sensor. The specific adsorption of both the receptor and the analyte on the electrode surface were probed to produce an amperometric sensor for mandelic and lactic acids.;Subsequently, the project has involved the investigation of small molecule adsorption, recognition and permeation at polymer plant wax constituent layers that model leaf cuticles. Correlations have been sought between the responses to these surfactants/adjuvants and the wax compositions. At low levels of interaction, the quartz crystal microbalance was used as a gravimetric sensor of these processes. At higher levels of interaction, when permeation of the film is sufficient to plasticise it, the rheological effects were used to explore solvent/small molecule permeation. In each case, qualitative data was used to diagnose film rigidity vs. viscoelasticity and quantitative data to determine film mass (thickness) or shear moduli, as appropriate. The experimental measurements have been supported by a computer model derived from the processes occurring at the interface and the resultant changes in film viscoelasatic properties are discussed.