Behaviour of phenol red pH-sensors in the presence of different surfactants using the sol-gel process
Behaviour of phenol red pH-sensors in the presence of different surfactants using the sol-gel process
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DOI：
10.1080/03067310902903738
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发表时间：
2010-01-01
影响因子：
2.6
通讯作者：
Al-Bawab, Abeer
中科院分区：
文献类型：
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作者：
El-Nahhal, Issa Mussa;Zourab, Shehata Mahmoud;Al-Bawab, Abeer
采用溶胶-凝胶法将酚红固定在聚硅氧烷基质中，制备了pH光学传感器。溶胶-凝胶是在酚红（PR）和合适的表面活性剂存在下，由正硅酸乙酯（TEOS）水解而成。采用不同的表面活性剂，即十六烷基三甲基溴化铵（CTAB），十二烷基二甲基氨基氧化物（GLA）和Triton X-100（TX-100）。有趣的是，表面活性剂的使用显着改善了二氧化硅的介观结构，并增加了系统的孔隙率。与游离PR的pH值范围（0.0 - 3.0和6.5-9.5）相比，两个响应pH值范围分别移至pH0.0 - 3.0和pH10.5 -1.5M [OH-]。结果发现，pH响应和酚红的pKa位移依赖于，不仅对二氧化硅基质，但也对表面活性剂的离子性质。在离子型表面活性剂如CTAB或GLA的情况下，进一步向更酸性和更碱性的pH偏移，而在非离子型表面活性剂如TX-100的情况下，没有观察到pH曲线的显著变化。
Phenol red was immobilised into a polysiloxane matrix using a sol-gel process to form pH optical sensors. The sol-gel was obtained by hydrolysis of tetraethoxysilane (TEOS) in the presence of phenol red (PR) and the appropriate surfactant. Different surfactants, namely cetyltrimethylammonium bromide (CTAB), dodecyldimetyl amino-oxide (GLA) and Triton X-100 (TX-100), were employed. Interestingly, the use of surfactants significantly improved the mesostructure of the silica and increased the porosity of the system. The two response pH ranges were shifted to pH 0.0-3.0 and pH 10.5-1.5M [OH-] compared with those of the free PR (pH 0.0-3.0 and pH 6.5-9.5). It is found that the pH response and the pKa shift of the phenol red were dependent, not only on the silica matrix but also on the ionic properties of surfactants. In the case of ionic surfactants such as CTAB or GLA, there was further shift to more acidic and more basic pH, whereas in the case of non-ionic surfactants such as TX-100 no significant change of the pH curve was observed.