The effect of the structures and functionality of thiol-compounds on the curing behavior of thiol/ene systems cured under ultraviolet was measured by using the conversion of thiol and C＝C groups by real-time FTIR. Under the same conditions, activity of thiolphenol is much lower than that of thiols. An electron withdrawing group on the benzene ring (ester group) can decrease the reaction activity, but an electron donating group on the aliphatic compound (isopropyl group) can increase it. The charge and bond length of the hydrosulfide group were calculated using the B3LYP/6-31G* of DFT. It was found that the electron withdrawing group on the benzene ring decreased the charge of S atom and shortened the SH bond length; the electron donating group on the aliphatic compound increased the charge and the bond length. These facts support the result of real-time FTIR, which discloses the mechanics to affect the reaction activity by the structures of thiols sufficiently.

Key words: system of thiol/ene, ultraviolet curing, real-time FTIR, charge, bond length