Slanted columnar thin films prepared by glancing angle deposition functionalized with polyacrylic acid polymer brushes

Three-dimensional inorganic nanostructured thin films with slanted columnar morphologies are functionalized with organic polymer brushes to fabricate a nanohybrid functional material. Nanostructured thin films are fabricated by glancing angle deposition of silicon onto silicon or gold to produce slanted columnar thin films (SCTFs). Polymer brushes are regarded as very promising nanomaterials for surface coatings because these systems are capable of responding to external stimuli such as temperature or pH, generally by reversible swelling/deswelling behavior. The fabrication of the SCTF as well as the stepwise reactions of poly(acrylic acid) guiselin polymer brushes to the SCTF nanocolumns are characterized with generalized ellipsometry and scanning electron microscopy. This study demonstrates that SCTFs are capable of withstanding the polymer brush grafting-to process and that both ellipsometry and electron microscopy indicate polymer brush immobilization within the void spaces of the SCTF. Furthermore, in situ combinatorial ellipsometry and quartz crystal microbalance with dissipation both reveal that the brushes retain their ability to swell/deswell with changes in pH of buffer solution. These tunable nanohybrid functional materials with increased surface area, complex columnar geometries, and stimuli-responsive characteristics provide novel material surfaces for nanoelectronics, biotechnology, and a variety of other advanced material applications.