Directed growth of poly(isobenzofuran) films by chemical vapor deposition on patterned self-assembled monolayers as templates.

This paper describes a method to direct the formation of microstructures of poly(isobenzofuran) (PIBF) by chemical vapor deposition (CVD) on chemically patterned, reactive, self-assembled monolayers (SAMs) prepared on gold substrates. We examined the growth dependence of PIBF by deposition onto several different SAMs each presenting different surface functional groups, including a carboxylic acid, a phenol, an alcohol, an amine, and a methyl group. Interferometry, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC), and optical microscopy were used to characterize the PIBF films grown on the various SAMs. Based on the kinetic and the spectroscopic analyses, we suggest that the growth of PIBF is surface-dependent and may follow a cationic polymerization mechanism. Using the cationic polymerization mechanism of PIBF growth, we also prepared patterned SAMs of 11-mercapto-1-undecanol (MUO) or 11-mercaptoundecanoic acid (MUA) by microcontact printing (microCP) on gold substrates as templates, to direct the growth of the PIBF. The directed growth and the formation of microstructures of PIBF with lateral dimensions of 6 microm were investigated using atomic force microscopy (AFM). The average thickness of the microstructures of PIBF films grown on the MUO and the MUA patterns were 400 +/- 40 nm and 490 +/- 40 nm, respectively. SAMs patterned with carboxylic acid salts (Cu2+, Fe2+, or Ag+) derived from MUA led to increases in the average thickness of the microstructures of PIBF by 10%, 12%, or 27%, respectively, relative to that of control templates. The growth dependence of PIBF on the various carboxylic acid salts was also investigated using experimental observations of the growth kinetics and XPS analyses of the relative amount of metal ions present on the template surfaces.