1. The Dow Chemical Company, Central Research and Development Advanced Polymeric Systems Laboratory, 1712 Building, Midland, Michigan 48674, The Dow Chemical Company, Central Research and Development Materials R&D Laboratory, 1702 Building, Midland, Michigan 48674, The Dow Chemical Company, Michigan Research and Development Analytical Sciences, 1897 Building, Midland, Michigan 48667, and National Institute of Standards and Technology, Gaithersburg, Maryland 20899