Surface photochemical modification and micropatterning with molecular level control.

摘要

In this thesis, we report a novel and simple photolithographic approach to modify the surface functionality and pattern the chemical functionality at the surfaces of polymers and self-assembled monolayers. Functional groups are introduced at polymer surfaces by surface segregation of photo-active block copolymer brushes. The polymer brush layers are formed by thermodynamically driven surface segregation of P(S-b-tBA) to the surface of polystyrene thin films. Functional groups are built into the azobenzene self-assembled monolayers as end groups during synthesis. The surface pattern is achieved through subsequent photochemical end group modification. In both systems, added photoacid generator causes hydrolysis of the tert butyl ester groups to carboxylic acids upon exposure to UV light. The success of surface pattern formation is demonstrated either by fluorescent microscope imaging of polymer surfaces, or by water condensation on self-assembled monolayers. Numerous techniques including X-ray, photoelectron Spectroscopy (XPS), water contact angle and ellipsometry were used to characterize ultrathin films of diblock copolymer polymer brushes and self-assembled monolayers. XPS and contact angle measurements are also used to confirm the changes in surface chemistry and wettability in each step of surface derivatization. Examples of patterned external ligands based on the “template assisted self-assembly” concept are presented: biomolecules are patterned on polymer surfaces and polymeric colloidal particles with micrometer and nanometer sizes are patterned on self-assembled monolayers surfaces. Another non-photolithographic technique for surface patterning, the UV/ozone oxidation technique, is also introduced at the end of this thesis and this technique is also used to pattern fluorescent nanoparticles on polymer templates.