A method for the deposition of controllable chemical gradients

A new methodology for creating surface chemical gradients is reported. By way of a demonstration of the technique, gradients of amine/carboxyl and of hydrocarbon/carboxyl functionality are deposited over a distance of 11 mm. The gradient chemistries are examined by X-ray photoelectron spectroscopy (XPS) and chemical derivatisation of acid functional groups by TFE labelling.