Design and use of functional polymers for surface modification of gold and polyethylene

Surface modification continues to be an important area of research because of the many cases where surface properties affect the utility of an underlying metal or organic polymer substrate. Over the past few years there has been considerable interest in developing effective and selective procedures to usefully modify the surface of common polymers. There is also increasing interest in organic thin film chemistry where thin films are supported on more defined inorganic surfaces. A new technique called hyperbranched grafting for ultra-thin film synthesis has been developed. Here it is shown that hyperbranched grafting with alpha,o-diaminopoly(tert-butyl acrylate) is suitable for modification of softer, less-defined polymer surfaces as well as defined inorganic surfaces. Using oxidized polyethylene and gold plated silicon wafers as substrates, the mild conditions of this hyperbranched chemistry affords a covalently modified ultra-thin film containing significant amounts of grafted poly(acrylic acid). Repetitive cycles of grafting insure a highly functionalized film. These surfaces are suitable for further chemical modification using covalent chemistry, ionic chemistry and hydrogen bonding chemistry.