Ultraviolet-curable optically clear resins using novel fluorinated imide-modified urethane acrylates

Homologs of novel fluorinated aromatic imide-modified urethane acrylate oligomers (FI-UAs) with different flexible methylene chain lengths were successfully synthesized using 4,4-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA)-based diimide diols (FI-OHs), isophorone diisocyanate (IPDI), and 2-hydroxyethyl methacrylate (HEMA). Ultraviolet (UV)-curable optically clear resins (OCRs) were prepared using these oligomers, and the UV-curing behavior of these resins was studied by monitoring the CC bond conversion and gel fraction while varying the UV dose. The thermal (glass transition temperature and thermal stability), optical (transmittance, yellowness, and haze), and adhesion properties of the cured films were investigated. The cured films of the resins exhibited improved thermal and optical properties, except for haze, which could be primarily due to the presence of fluorinated aromatic imide moieties in the oligomer. Furthermore, higher adhesion and improved haze were observed with increasing methylene chain length of FI-UA oligomers.