Block copolymer self-assembly is an innovative technology capable of patterning technologically relevant substrates with nanoscale precision for a range of applications from integrated circuit fabrication to tissue interfacing, for example. In this article, we demonstrate a microwave-based method of rapidly inducing order in block copolymer structures. The technique involves the usage of a commercial microwave reactor to anneal block copolymer films in the presence of appropriate solvents, and we explore the effect of various parameters over the polymer assembly speed and defect density. The approach is applied to the commonly used poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) families of block copolymers, and it is found that the substrate resistivity, solvent environment, and anneal temperature all critically influence the self-assembly process. For selected systems, highly ordered patterns were achieved in less than 3 min. In addition, we establish the compatibility of the technique with directed assembly by graphoepitaxy.

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The creation of gold surfaces modified by single- or double-stranded DNA self-assembled monolayers (SAMs) is shown to produce heterogeneous surface packing densities through the use of electrochemical studies coupled with fluorescence imaging. The modified surfaces created by direct adsorption of thiolate DNA [followed by passivation with mecaptohexanol (MCH)] resulted in regions covered by a monolayer of DNA SAM and other regions that were coated by large particles of DNA. The difference in fluorescence intensity measured from these regions was dramatic. More importantly, a regional variance in fluorescence intensity in response to electrochemical potential was observed: the large aggregates showing a significantly different modulation of fluorescence intensity than the monolayer-coated regions. Electrochemical desorption and detection of the fluorescently tagged DNA provided clear evidence of a complete surface modification. These studies have implications for biosensor/biochip development using DNA SAMs. A modification in the method used to produce the DNA SAMs resulted in a significantly different surface with much fewer aggregates and more significant electromodulation of the fluorescence intensity, though at much lower DNA surface density (ca. 1% of maximum theoretical coverage). This method for forming the modified surfaces has clear advantages over the currently accepted practice and emphasizes the importance of studying the nonaveraged nature of the sensor surface using in situ imaging tools like electrofluorescence microscopy.