Macromolecules 35 (2002) 5873-5882.

Identification and Quantitation of Urea Precipitates in Flexible Polyurethane Foam Formulations by X-ray Spectromicroscopy

E. G. Rightor,* , S. G. Urquhart, , A. P. Hitchcock, H. Ade, A. P. Smith, ,| G. E. Mitchell, R. D. Priester,A. Aneja, # G. Appel, G. Wilkes # and W. E. Lidy ^

Analytical Sciences, The Dow Chemical Company, 1897 Building, Midland, Michigan 48667
Department of Physics, North Carolina State University, Raleigh, North Carolina 27695
Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON L8S 4M1 Canada
^ Polyurethanes, Dow Chemical, Building B-1608, 2301 N. Brazosport Blvd., Freeport, Texas 77541
# Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Received December 28, 2001

ABSTRACT: Scanning transmission X-ray microscopy (STXM) and atomic force microscopy have been used to study the morphology and chemical composition of macrophase-segregated block copolymers in plaque formulations based on water-blown flexible polyurethane foams. Although there has been a large body of indirect evidence indicating that the observed macrophase-segregated features in water-rich polyurethane foams are due principally to urea components, this work provides the first direct, spatially resolved spectroscopic proof to support this hypothesis. The STXM results are consistent with a segregation model where urea segments segregate, forming enriched phases with the majority of the polyether- polyol and urethane groups at the chain ends of the urea hard segments. Chemical mapping of the urea, urethane, and polyether distribution about the urea-rich segregated phases showed that the urea concentration changes gradually (across several hundred nanometers) in a butylene oxide-based foam. This mapping also showed the urea-rich segregated phases present as a partial network in an ethylene oxide/propylene oxide sample.

10.1021/ma0122627 CCC: 2002 American Chemical Society