Relationship between bound fraction and glass transition temperature of poly(methyl methacrylate) adsorbed on modified silica surfaces

POLY 92

Rajesh Madathingal, rajesh@temple.edu and Stephanie L. Wunder, slwunder@temple.edu. Department of Chemistry, Temple University, 13th and Norris Streets, 1901 N. 13th Street, Philadelphia, PA 19122
In polymer nanocomposites, the contribution of adsorbed polymers to composite properties becomes increasingly important as the filler size decreases. In order to investigate the effect of polymer-surface interactions for PMMA/silica interfaces, adsorption isotherms, Tgs and FTIR spectra were obtained for PMMA on thermally and chemically modified silica (SiO2). The silanol (SiOH) group density was varied by heat/acid treatment at successively higher temperatures, or the surface was made hydrophobic by reaction with hexamethyldisilane. Plateau PMMA adsorption (by TGA) increased with increasing SiOH density, and was least for hydrophobically modified SiO2. Similarly, the bound PMMA fraction, measured by the relative intensity of the hydrogen bonded and free carbonyl of PMMA, increased with increasing SiOH density, and no hydrogen bonded fraction was observed for methylated SiO2. At comparable PMMA coverage, Tg (by DSC) increased with increasing SiOH density, and decreased for methylated silica, with respect to Tg of bulk PMMA.
 

General Papers: Polymers in Nanotechnology
1:00 PM-5:00 PM, Sunday, August 19, 2007 Westin Boston Waterfront -- Douglas, Oral

Division of Polymer Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007