Synthesis and Characterization of Poly(isobenzofuran) Films by Chemical Vapor Deposition

TitleSynthesis and Characterization of Poly(isobenzofuran) Films by Chemical Vapor Deposition
Publication TypeJournal Article
Year of Publication2006
AuthorsChoi, H-G, Amara, JP, Swager, TM, Jensen, KF
Date Publishedjun
Keywordsgold substrate thiol monolayer polymn catalyst polyisobenzofuran prepn, polyisobenzofuran film prepn chem vapor deposition polymn, tetrahydroepoxynaphthalene monomer precursor chem vapor deposition polyisobenzofuran prepn

This paper describes the synthesis and properties of poly(isobenzofuran) (PIBF) films prepd. by a thermal chem. vapor deposition (CVD) process. The synthesized precursor monomer, 1,2,3,4-tetrahydro-1,4-epoxynaphthalene, is pyrolyzed by flowing it through a tube furnace at temps. of 600-750°. A reactive intermediate, isobenzofuran (IBF) monomer, is produced by this pyrolysis and deposited onto a silicon substrate where it polymerizes to form a thin coating of poly(isobenzofuran) (PIBF) on the surface. The chem. structure and compn. of the PIBF films are supported by NMR spectroscopy, Fourier transform IR spectroscopy (FT-IR), and XPS. The wt.-av. mol. wt. of the PIBF films range from 5500 to 9400 by varying the deposition (stage), pyrolysis (furnace), and vaporization (source) temps. With the variation of deposition temp. (5, 10, 15, 20, 25°) and pyrolysis temp. (600, 650, 700, 750°), significant changes are obsd. in deposition (growth) rate, mol. wt., and morphol. while the chem. structure of the PIBF films remain the same as probed by FT-IR and XPS anal. On the other hand, variation of the vaporization temp. (40, 45, 50, 55, 60°) leads to significant changes in the chem. structure as well as in the deposition rate, mol. wt., film uniformity, and morphol. By exploring several operating conditions, we have obtained optimal conditions for deposition temp. (10°), pyrolysis temp. (750°), and vaporization temp. (60°) that provide good film properties as well as fast film growth. To investigate the possible role of cationic initiation in IBF polymn., PIBF films were deposited on several surfaces tailored with self-assembled monolayers (SAMs) of thiols that have functional groups of different acidities, including a carboxylic acid (-COOH), a phenol (-PhOH), an alc. (-OH), an amine (-NH2), and a Me group (-CH3). We obsd. the fastest growth of PIBF (k = 2.5 \AA/s) on the carboxylic acid-terminated surfaces whereas the slowest growth was on the methyl-terminated surfaces (k = 0.02 \AA/s). On the basis of the exptl. observations, we proposed a growth mechanism for the PIBF films by the CVD process. [on SciFinder(R)]