Field-Induced Nanolithography for Patterning of Non-Fouling Polymer Brush Surfaces

Speaker: 
Robert Ferris
Date of Seminar: 
Wed, 2011-09-21 11:45
Semester & Year: 
Fall 2011
Seminar Location: 
Hudson 125
Seminar Contact(s): 
Chad Gibbs: scg8@duke.edu
Special Instructions: 
Lunch will be provided between 11:45AM and the beginning of the seminar at noon
We demonstrate, for the first time, a facile method for the direct electrochemical patterning of hydrophilic polymer brushes in ambient conditions. Using a method we term field-induced nanolithography (FINL), we have patterned four different types of hydrophilic polymer brushes; poly(acrylic acid) (PAA), poly(N-isopropylacrylamide) (PNIPAAm), poly(sulfobetaine methacrylate) (PSBMA), and poly(oligo(ethylene glycol) methyl methacrylate) (POEGMA). Brushes were synthesized by surface initiated polymerization on conductive silicon or gold substrates. FINL patterning of polymer brushes requires the correct bias voltage polarity and results from the localized electrochemical reaction that occurs between the top metal electrode and the polymer brush surface. For POEGMA brushes specifically we report pattern width and depth as a function of applied voltage, relative humidity, and exposure time. Using X-ray photoelectron spectroscopy and aldehyde reactive reagents, we demonstrate that FINL locally oxidizes the surface of the non-fouling POEGMA brushes to form reactive aldehyde groups. This local chemical activation of non-fouling POEGMA brushes provides a promising platform for bio-sensor device development.