Control of TiO2 Growth Conditions Using Tetrahydropyran Protected Self-Assembled Monolayer and Alkyl Isocyanate

The control of TiO2 growth condition on tetrahydropyran (THP)-2-carbamate propyl triethoxysilane (TCPES) using thermal heating and octyl isocyanate (OIC) was investigated. TiO2 can be grown on surfaces terminated with -OH and -NH2 groups from an aqueous solution of about pH 3. However, TiO2 did not deposit on the -CH3 terminated surfaces due to the low surface energy of these surfaces. The -THP functional group can be removed, and the surface functional group can be converted to -NH2 by heating the material over 200 degrees C. OIC can then be immobilized on the surface after heating, changing the surface functional group from -NH2 to -CH3. As TiO2 can be deposited from a solution on a -NH2 terminated surface but not a -CH3 terminated surface, TCPES can be used to switch the surface properties by thermal activation and subsequent reaction with OIC. This approach has the potential to be used for site-selective deposition of TiO2 on surfaces.