Structural and electronic effects on the efficiency of DMNB detection with fluorescent conjugated polymers are described.

A self-polymerizable AB-type monomer for Diels−Alder (D−A) polymerization was prepared, and its polymerization was carried out in the melt phase and at high pressure in solution. The former method generated only low-molecular-weight polymer, but the latter one offered an efficient polymerization with increased molecular weight, due to the effect of high pressure on reactions with a negative activation volume. A pyridinium p-toluenesulfonate-catalyzed dehydration reaction of the D−A polymer led to a novel aromatic ladder polymer, poly(iptycene), which is soluble in common organic solvents and stable up to 350 °C. The NMR and UV−vis spectra of these polymers match the spectra of their corresponding model compounds, the synthesis of which is also reported.

Several poly(phenylene ethynylene)s with pendant hexafluoro-2-propanol (HFIP) groups have been synthesized and characterized in terms of their solution and thin-film optical properties. The incorporation of strongly hydrogen-bond-donating HFIP groups into conjugated polymers is shown to greatly enhance their fluorescence response upon exposure to the vapors of several hydrogen-bondaccepting analytes such as pyridine and 2,4-dichloropyrimidine. The enhanced sensitivity of these conjugated polymer-based chemosensors is the result of stronger analyte/polymer binding interactions and more facile photoinduced charge-transfer reactions with hydrogen-bonded analytes.

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This paper describes the synthesis and properties of poly(isobenzofuran) (PIBF) films prepared by a thermal chemical 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 temperatures of 600-750 °C. 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 chemical structure and composition of the PIBF films are supported by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The weightaverage molecular weight of the PIBF films range from 5500 to 9400 by varying the deposition (stage), pyrolysis (furnace), and vaporization (source) temperatures. With the variation of deposition temperature (5, 10, 15, 20, 25 °C) and pyrolysis temperature (600, 650, 700, 750 °C), significant changes are observed in deposition (growth) rate, molecular weight, and morphology while the chemical structure of the PIBF films remain the same as probed by FT-IR and XPS analysis. On the other hand, variation of the vaporization temperature (40, 45, 50, 55, 60 °C) leads to significant changes in the chemical structure as well as in the deposition rate, molecular weight, film uniformity, and morphology. By exploring several operating conditions, we have obtained optimal conditions for deposition temperature (10 °C), pyrolysis temperature (750 °C), and vaporization temperature (60 °C) that provide good film properties as well as fast film growth. To investigate the possible role of cationic initiation in IBF polymerization, 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 alcohol (-OH), an amine (-NH 2 ), and a methyl group (-CH 3 ). We observed the fastest growth of PIBF (k ) 2.5 Å/s) on the carboxylic acid-terminated surfaces whereas the slowest growth was on the methylterminated surfaces (k ) 0.02 Å/s). On the basis of the experimental observations, we proposed a growth mechanism for the PIBF films by the CVD process.