Pulsed plasma chemical functionalization of solid surfaces

Abstract

Pulsed plasma polymerization provides a highly efficient, single step, solventless method of surface functionalization. These surfaces can then be further derivatlzed for particular applications. The motivation underlying this work is to utilise this technique for a variety of applications to improve on existing methods of surface treatment. This approach is substrate independent and not hindered by geometry and in most cases the number of reactions stages required reach the desired product can be noticeably reduced. Applications for surface coatings produced in this research cover a wide area for example a single step method of manufacturing a thermally responsive coating for cell culture has been developed. Previous preparative methods have required three of more steps to produce the desired surface which comprises poly(n-isopropylacrylamide) and although attempts have been made employing plasma polymerization, the depositions were carried out under continuous wave conditions, resulting in Irreversible adsorption of proteins at temperatures above that of the lower critical solution temperature. A significant increase in structural retention and a lesser degree of cross-linking resulting from the use of pulsed conditions in this work has eliminated this major drawback. The versatility of pulsed plasma chemical functionalization has also been exemplified by the surface immobilization of various Initiating groups that can be further deployed to grow polymer brushes from the surface by a variety of well-established methods including atom transfer radical polymerization. This method has found to be suitable for a wide range of substrates such as silicon, polytetrafluoretylene and polystyrene beads. The formation of block copolymers and microscopic polymeric arrays has also been possible. Plasma polymer coatings generated from nitrogen-containing precursors have allowed the surface attachment of a Palladium catalyst, which in turn facilitates the electrode less deposition of transition metals. Previously, catalysts could not be adhered to a substrate In less than four or five individual steps. The approach adopted here achieved the desired results in just two reaction stages.