Novel synthesis of hierarchically structured block copolymer/layered silicate nanocomposites

POLY 89

Ross E Behling, behling@iastate.edu, Department of Chemical & Biological Engineering, Iowa State University, 2114 Sweeney Hall, Ames, IA 50011 and Eric W. Cochran, Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011.
Here we report the synthesis and characterization of highly exfoliated polymer/layered silicate nanocomposites synthesized via a graft-from approach using atom transfer radical polymerization (ATRP) on montmorillonite clay (MMT) functionalized with a bromo-alkyl initiator. Sonication coupled with careful control of the ATRP kinetics successfully disperses clay aggregates, facilitating a high degree of exfoliation and a narrow molecular weight distribution (Mw/Mn < 1.2). We further regulate the synthetic process to produce block copolymers (BCP) in a second reaction. Both polymer blocks exhibit elevated glass transition temperatures as measured by differential scanning calorimetry.

As observed by transmission electron microscopy, the formation of hierarchical structures is driven by microphase separation of the BCP's subject to the confined geometry imposed by the planar MMT particles and the processing conditions. In this contribution we show the relationship between morphology, molecular parameters, and processing conditions using a complement of microscopy, scattering, and mechanical analysis techniques.

 

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