Multi Self-Healable UV Shielding Polyurethane/CeO₂ Protective Coating: The Effect of Low-Molecular-Weight Polyols

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., M = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of M 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO₂ was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO₂) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO₂ coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO₂-P) showed similar self-healing properties. The PU-11-3-3-CeO₂-P coating also showed excellent UV shielding in real outdoor exposure conditions.