X-Ray Photoelectron Spectroscopy and Atomic Force Microscopy of High-Solid Polyurethane Resins

Abstract

High-solid polyester polyol resins and high-solid acrylic polyol resins were synthesized, cured by isophorone diisocyanate trimer (IPDI) to obtain polyurethane films, and then characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS analysis showed that the top layers of these polymer films are dominated by the soft segments of the resins; the IPDI segments tend to remain inside the bulk. The polyester resins cured by IPDI at room temperature show more soft segments than these resins cured by IPDI at 120°C. Thechange in mole ratios of hydroxyl to carboxylic and/or anhydride groups during the synthesis of the resins does not give rise to distinct variation in surface composition in our experimental range. AFM topographic images demonstrate that high-solid resins cured by IPDI exhibit numerous grains or aggregates on the surfaces, while low-solid resins cured by IPDI produce surfaces with only a few aggregates. Curing temperature, such as room temperature or 120°C, does not cause distinct differences in topographic images. Higher hydroxyl content of the resins results in smaller grains or aggregates on the surfaces. High-solid acrylic polyol resins cured by IPDI give rise to separated aggregates surfaces, which is different from high-solid polyester polyol resins cured by IPDI. High-solid Polyester polyol resin Acrylic polyol resin XPS AFM