Waterborne polyurethanes: Spectroscopy and stability of emulsions

We prepared waterborne polyurethanes based on isophorone diisocyanate, dimethylolpropionic acid, polyhexane neopentyl adipate glycol, or polyethylene-butylene adipate glycol through self-emulsion (a prepolymerization process). Their IR and NMR spectroscopic properties were investigated, and the peaks of these spectra were assigned. The stability of the emulsions was studied on the basis of the shelf life and particle size distribution of emulsions. The effects of solvents, hard-segment content, carboxylic group content, extenders, and feeding methods on the stability of the emulsions were determined to show that N-methylpyrrolidone was a good solvent for retaining the stability of emulsions; particle sizes decreased with increasing COOH content and decreasing hard-segment content, whereas the extenders and feeding Methods studied had little effect on the stability of the emulsions. The causes of the stability of the emulsions are discussed according to the analysis of the molecular and particulate structures. (c) 2006 Wiley Periodicals, Inc.