Patterned Surfaces Combining Polymer Brushes and Conducting Polymer via Colloidal Template Electropolymerization

Abstract

Recently, there has been a signifi cant interest in the fabrication of patterned polymer surfaces because of potential applications in surface-based technologies such as microfl uidic devices, chemical/biosensors, platforms for tissue engineering, etc. [ 1 ] To date, polymer brushes are widely used in patterning surfaces due to their robustness, broad range of chemical and mechanical properties, and ability to modify surface properties, [ 2 ] and thus an ideal surrogate for self-assembled monolayers (SAM)s. Despite the numerous applications of patterned polymer surfaces, there have been a limited number of strategies reported toward the formation of laterally well-defi ned binary composition patterned brushes. [ 3 ] Most of the methods used involve expensive, tedious and complex lithographic techniques, [ 4 ] which limits their practical applications. Another material of high interest are conducting polymers, which are a versatile class of organic materials with electrical, optical, and electrochemical properties that are easily modifi ed by design and synthesis. They are useful as display materials, semi-conductors, electrochromic devices, fl uorescent materials, non-linear optical materials, electromagnetic shielding, and various types of industrial coatings for anti-corrosion and anti-static purposes. [ 5 ] Due to their unique properties, conducting polymers [ 6 ] are also being exploited in making 2D nano/microstructured arrays because of the many applications such as photonic crystals, diffraction gratings, biosensors, and surface-enhanced Raman scattering (SERS). [ 7 ] The electropolymerization technique endows several advantages -ease in control of thickness and lateral dimension of the pattern, site-directed patterning, and deposition over large surface areas onto various conducting substrates. One unique electrodeposition approach is by template-assisted electropolymerization, which has remained largely unexplored for 2D patterning. To our knowledge, this is the fi rst report on binary composition patterned surfaces combining a conducting polymer and a polymer brush via a simple approach of colloidal template-assisted electropolymerization followed by growing the polymer brush, using surface initiated atom transfer radical polymerization (SI-ATRP). This study is also the fi rst account on dual patterned inverse colloidal crystals (in a single layer assembly) of electrodeposited conducting polymer and an SI-ATRP initiator. The generic method reported here should be useful for making different types of binary patterned surfaces using different combinations of polymer brushes, conducting polymers, and self-assembled monolayers. The importance of such combinations may be found in redox-active ( π -conjugated polymer-based) stimuli-responsive polymer brushes and modulation of electro-optical properties simultaneous with changes in solvent swelling properties (polymer brushes), dependent on the binary composition and mode or size of patterning.The protocol for stepwise patterning of binary patterned polymer su...

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