Dimerization of polyanthracene in polymethylmethacrylate for reversible light-induced surface modification
The dimerization of polyanthracene and its monomer anthracene was characterized, and the kinetics of dimer breaking was studied through contact angle measurements upon exposure to ultraviolet light. UV-vis spectroscopy studies showed that dimerization and breaking wavelengths for anthracene and polyanthracene were in the ultraviolet region of the spectrum. Formation of the dimer, which corresponds to increase in surface hydrophobicity, occurred at 302 nm for polyanthracene, and 310 - 340 nm for anthracene. Breaking of the dimer, which corresponds to increase in surface hydrophilicity, occured at 224 nm for polyanthracene, and 240 - 260 nm for the anthracene monomer. Absence of absorption peaks in the visible region suggest material stability under visible light. The polymer material coated on a polymethylmethacrylate substrate exhibited increase in hydrophilicity over time upon exposure to UV-C light.