巯基化合物结构对巯基/乙烯基共聚体系紫外光固化反应活性的影响

运用FTIR原位跟踪方法, 以巯基和碳碳双键官能团转化率做为检测指标, 研究了巯基化合物的结构对紫外光固化巯基/乙烯基共聚体系固化行为的影响. 在相同的反应条件下, 苯硫酚的反应活性明显低于硫醇的反应活性; 巯基化合物中吸电子基团(酯基)会使反应活性降低, 而推电子基团(异丙撑基)会使反应活性提高. 采用量子化学中密度函数理论B3LYP/6-31G*的方法和基组对巯基化合物中S与H的净电荷和键长计算结果表明：吸电子基团使S上的净电荷减少, 其与H的共价键键长缩短; 而推电子基团的作用则相反. 此结果佐证了FTIR的实验结果, 揭示了巯基化合物结构对巯基/乙烯基共聚体系紫外光固化反应活性的影响机理.

Structural Effect of Thiol-Compounds on the Activity of Thiol/ene System Cured by Ultraviolet

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 elec-tron 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.