Micromolding Surface-Initiated Polymerization for Shrinking Surface Microfeatures

Hydrophobic polymer films can be grown on a surface in order to prevent reactions and corrosion on a surface due to water.  By molding a master with distinct microfeatures and growing a polymer film that deviates from the original in only one dimension, films can be eventually altered in a way that physically improves the hydrophobicity.  This experiment, through the polymerization of a hydrophobic monomer on a gold substrate activated with Grubbs catalyst, investigated the resultant height decrease from growing a polymer film in a polydimethylsiloxane (PDMS) mold of a given master.  The dimensions of the microfeatures of the master, PDMS molds, and resultant polymer films were then characterized using an atomic force microscope (AFM).  These runs occurred over the course of ten weeks, much of which was spent determining and improving the proper procedure with which to generate the polymer films.  Consistent results showed an over fifty percent height reduction in the heights of micropyramids on the master to the grown pyramids on the film, without a significant change in the base dimensions of the pyramids.  Other shapes, such as inverted pyramids, were also grown starting from different masters, demonstrating the versatility of the method.  The growth method tested has proven its ability to alter aspect ratios in replication and to work on the microscale, and should provide a springboard for future hydrophobicity research.