AVS 46th International Symposium
    Biomaterial Interfaces Group Tuesday Sessions
       Session BI-TuA

Paper BI-TuA8
Contact Mechanical Properties of Confined NIPAM Films at the Biomaterial Interfaces

Tuesday, October 26, 1999, 4:20 pm, Room 613/614

Session: Characterization of Biomaterial Interfaces
Presenter: R. Luginbuehl, University of Washington
Authors: R. Luginbuehl, University of Washington
M.D. Garrison, University of Washington
Y.V. Pan, University of Washington
R.M. Overney, University of Washington
B.D. Ratner, University of Washington
Correspondent: Click to Email
Smart polymeric materials, which change their structural properties upon stimulation, are of highest interest for industrial applications in surface coating and printing, sensor technology, biotechnology, medicine, and biomaterial research. Progress in precision engineered surfaces for biosensor applications strongly depend on appropriate techniques to analyze surfaces at the micro and nanometer level. Recently, considerable research effort has focused on the investigation of co-polymers and grafted polymers containing N-isopropylacrylamide (NIPAM). These polymers can be engineered to undergo thermally induced structural and mechanical phase transitions around 32 ºC, which is drawn by hydrophobic forces and hydrogen bonding. The structural phase transition is accompanied by a change in volume, and therefore a change in mechanical properties, as well as a change in the surface free energy. We carried out scanning force microscope (SFM) investigations on surface confined NIPAM films. Thin films (thickness < 10 nm) were obtained by polymerization on selected substrates. Novel SFM techniques permit the observation of the transition behavior at the nanometer scale. Photolithographically patterned thin films were used to isolate changes in the polymer structure relative to a reference substrate. Contact mechanical properties, volume transition, and the interfacial energy were monitored as a function of the system temperature. The introduced SFM technique offers a unique combination of microscopy with spectroscopic analysis of surface interactions and local subsurface structural properties.