Detail Structural investigation of copolymerization reactions in restricted dimensions Bibliografi Author: Weerasekera, Gayanga ; Duran, Randolph S. (Advisor) Topik: CHEMISTRY; ANALYTICAL|CHEMISTRY; POLYMER Bahasa: (EN )    ISBN: 0-599-82432-8     Penerbit: UNIVERSITY OF FLORIDA     Tahun Terbit: 2000     Jenis: Theses - Dissertation Fulltext: 9976621.pdf (0.0B; 0 download) Abstract When polymerized by conventional methods, active sites could attack in any direction. In Langmuir monolayers, not only has the reaction medium reduced from three dimensions to two, but also the monomer molecules are oriented in a specific way with respect to the air/water interface, under pressure. This specific orientation of the monomer should alter the reactivity compared to the solution polymerization. In this study we expected to find differences in a series of copolymers synthesized via Langmuir monolayer techniques versus conventional synthetic procedures by studying their molecular weight distribution, sequencing distribution, and the lateral order when spread in the air/water interface. Monomer mixtures of 3-hexadecyl pyrrole (3HDP) and N-octadecyl pyrrole (NODP) were polymerized in monolayers at aqueous surfaces, then transferred to hydrophobized silica substrates. While none of the compounds or their polymers could be transferred to hydrophilic substrates using Langmuir-Blodgett techniques, monomer monolayers could be transferred successfully to hydrophobic surfaces from water. Subsequent dipping apparently resulted in Y-type multilayers. Isotherms suggest that 80% and 60% mixtures of both 3HDP and NODP pack better on the air/water interface than 3HDP alone. Molar mass and initial sequence studies were performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOFMS). Further investigations of the polymer were done using ion trap mass spectrometry. Lateral ordering was investigated by X-ray diffraction, largely at synchrotron sources and including the Materials Research Collaborative Access Team (MRCAT) beamline at the Advanced Photon Source (APS) in Chicago, Illinois. A custom made glancing angle X-ray surface diffractometer was commissioned at Sector 10 (MRCAT) of the APS synchrotron at Argonne National Laboratory (ANL); this construction and commissioning was the main focus in the final year of this dissertation work. The primary goal was to collect data much faster (at this 7 GeV synchrotron source) than possible at National Synchrotron Light Source in order to observe structural evolution in real time during polymerization reactions. Several different X-ray detectors were tested to optimize the total experimental time. Curved and linear position sensitive detectors, as well as conventional Scintillation detectors with appropriate Soller slits, were tested. Double mirror X-ray beam steering optics and a custom designed Langmuir trough system have been built and installed for all users of the beamline. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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