Statistical Copolymer Brush Gradients:  A Versatile Platform for Investigating Reactions and Interactions at Interfaces

 

Derek Patton, Kirt Page, Michael Fasolka and Kathryn Beers

 

Tailored surface chemistry is critical to many schemes in bio- and nano-technology because surface properties can dictate biocompatibility, adhesion, wetting, structure, dispersion and other performance factors in devices, films and complex fluids.  For these and other applications, polymer brushes provide a robust and chemically versatile means for interfacial modification. Analogous to their bulk counterparts, statistical copolymer brushes result from the copolymerization of two monomers from surface-bound initiators, where the arrangement of monomers within the tethered chains is dictated by monomer reactivities.  Due to the lack of segmental rearrangement, these copolymer brush surfaces enable the expression of a statistical distribution of monomer constituents at the interface and consequently, provide a unique platform for studies of surface interactions for a broad range of applications.  In this work, we present a versatile method for fabricating statistical copolymer brush gradients via microchannel confined surface-initiated photopolymerization (µSIP).  Utilizing these gradients, we demonstrate a combinatorial approach to examine and screen the directed self-assembly of block copolymer thin films. In addition, we show that monomer reactivity ratios can be measured from surface-initiated polymerizations using X-ray photoelectron spectroscopy. This method eliminates several of the experimental complications of solution polymerizations and enables the use of brush gradient techniques. These experiments shed insight into the behavior of reactions at interfaces and represent one of the few methods reported for quantifying polymerization behavior from a surface.

 

Author name: Derek Patton

Mentor name: Kathryn Beers

Division: Polymers

Laboratory: MSEL

Building 224 Room B218

Mail Stop: 8542

Telephone #: 3586

FAX #: 4924

Email: derek.patton@nist.gov

Sigma Xi member: No

Category: Materials