玻璃硅烷化处理对罗丹明6G和亚甲基蓝吸附行为的影响

利用六甲基二硅烷胺对平面玻璃光波导(高折射率透明导光薄膜介质)进行硅烷化处理, 得到水接触角大于90°的疏水表面. 然后使用时间分辨光波导分光光谱技术研究水溶液中的罗丹明6G (R6G)和亚甲基蓝(MB)分子在疏水玻璃表面的吸附行为, 并与亲水玻璃条件下测得的结果进行对比. 对利用疏水玻璃光波导测得的R6G的吸附-脱附动力学曲线进行Langmuir拟合得到了R6G的吸附速率常数, 脱附速率常数以及吸附自由能. 并且发现与亲水玻璃情况相比, 吸附速率常数增大, 脱附速率常数减小, 吸附自由能更负. 在疏水玻璃表面形成的R6G和MB吸附层的吸光度与亲水玻璃情况相比显著升高, 表明这两种分子更倾向于吸附在疏水玻璃表面. 实验结果还发现玻璃硅烷化处理能够有效抑制这两种染料分子在表面的聚合反应.

Effect of Glass Silylation on the Adsorption Behavior of Rhodamine 6G and Methylene Blue

The silylation of thin-film glass sheets with hexamethyl disilazane results in hydrophobic glass surfaces with water contact angles larger than 90°. The adsorption behavior of Rhodamine 6G (R6G) and methylene blue (MB) molecules on the hydrophobic glass from the individual aqueous solutions were investigated by time-resolved optical waveguide spectroscopy and the experimental data were compared with those obtained using hydrophilic glass. The adsorption and desorption rate constants as well as the adsorption free energy for R6G adsorption on the silylated glass were determined by fitting the experimental data with the Langmuir isotherm model. Glass silylation leads to an increased adsorption rate constant, a decreased desorption rate constant, and an enhanced adsorption free energy as compared to those obtained for R6G adsorption on hydrophilic glass. The comparisons indicate that R6G and MB molecules prefer to adsorb onto hydrophobic glass over hydrophilic glass from aqueous solution. Moreover, it was observed that glass silylation can effectively prevent the aggregation of dye molecules at the water/glass interface.