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

Abstract

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 resins (FI-UARs) were prepared using these oligomers, and the UV-curing behavior of these resins was studied by monitoring the C=C 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. • A series of new fluorinated imide-modified urethane acrylates (FI-UAs) were synthesized by reacting 6FDA-based diimide-diol and diisocyanate, followed by capping with a hydroxyl functional acrylate. • Ultraviolet-curable fluorinated imide-modified urethane acrylates resins (FI-UARs) were prepared by combining novel FI-UAs, isobonyl acrylate (IBOA), and Irgacure 1173, which were used as oligomers, the monomer, and photoinitiator, respectively. • The cured FI-UAR films exhibited enhanced glass transition temperature, thermal stability, transmittance, and yellowness, which could be primarily due to the presence of fluorinated aromatic imide moieties in the oligomer. • In addition, the adhesion and haze of cured films were improved as the methylene chain length of the FI-UA oligomers increased.