Photogeneration of "Clickable" Surface-Bound Polymer Scaffolds

An experiment was conducted to show that a polymer modified with alkyne groups can be photoimmobilized onto a surface-bound phthalimide self-assembled monolayers (SAM), an aromatic carbonyl that can insert into aliphatic C-H bonds upon exposure to UV light, and that the alkyne groups of the UV irradiated and surface-bound polymer retain their Cu(I)-catalyzed reactivity toward azide groups. 11-Phthalimidoundecanetrimethoxysilane was synthesized and self-assembled on Si and glass to form SAM 1. Polymer films were prepared by spin-coating a solution of the polymer in toluene at a speed of 3000 rpm for 90 s onto SAM 1. Films were placed in argon-purged quartz tubes and irradiated for 90 min with a Rayonet Photochemical Reactor equipped with lamps that emit at 300 nm. Ungrafted chains were removed by sonicating in toluene for 5 min. Sonication was repeated two additional times, changing the vial and solvent each time. A 75-mesh TEM grid was used as the photomaskfor the patterning experiments. Spin-coated films on SAM 1 were masked and irradiated with a UVP multiray lamp containing an 8-W 300-nm Rayonet bulb for approximately 2 h at ambient conditions. Patterns were visualized by spincoating a solution of 0.64% triphenyl sulfonium triflate and 8% PS in propylene glycol monomethyl ether acrylate onto the pattern at 2500 rpm. Both ellipsometry and H2O contact angle measurements confirm the presence of polymer after rinsing films on SAM 1 that were irradiated with UV light. The covalent attachment of the polymer makes the films stable when placed in organic solvents and can be used to study interfacial organic reactions on alkyne groups attached to the photografted polymer.