1. Jackson Laboratory, E. I. du Pont de Nemours & Co., Deepwater, New Jersey 08023; E. I. du Pont de Nemours & Co., Corporate Center for Analytical Sciences, Experimental Station, Wilmington, Delaware 19880-0323; Department of Chemistry and Physics, Rowan University, Glassboro, New Jersey 08028; and Emulsion Polymers Institute and Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015-4732