Cross Metathesis on Olefin-Terminated Monolayers on Si(111)Using the Grubbs' Catalyst

摘要

This paper reports the functionalization and patterning of olefin-terminated monolayers on Si(111)through cross metathesis.A simple,one-step synthesis of a diolefm-CH_2=CH(CH_2)_9O(CH_2)_9CH=CH_2-was developed from commercially available starting materials.Mixed partially olefin-terminated monolayers of this novel diolefin and 1-octadecene on hydrogen-terminated Si(111)were obtained.The olefins are raised above the rest of the monolayer and thus sterically accessible for further functionalization.Olefin-terminated monolayers were reacted with the Grubbs' first generation catalyst and olefins in solution that were terminated with fluorines,carboxylic acids,alcohols,aldehydes,and alkyl bromides.Characterization of these monolayers using X-ray photoelectron spectroscopy and horizontal attenuated total reflection infrared spectroscopy demonstrated that olefins on the surface had reacted via cross metathesis to expose fluorines,carboxylic acids,aldehydes,alcohols,and bromides.Through calibration experiments,we demonstrated a simple 1:1 correspondence between the ratio of olefins in solution used in the assembly and the final composition of the mixed monolayers.Finally,these monolayers on silicon were patterned on the micrometer-size scale by soft lithography using microfluidic channels patterned into poly(dimethylsiloxane)(PDMS)stamps.Micrometer-wide lines of polymer brushes were synthesized on these monolayers and characterized by scanning electron microscopy.In addition,olefin-terminated monolayers were patterned into micrometer-sized lines exposing carboxylic acids by cross metathesis with olefins in solution.This method of patterning is broadly applicable and can find applications in a variety of fields including the development of biosensors and nanoelectronics.