Browsing by Subject "molecular-weight"
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Item Thermodynamic Synthesis of Solution Processable Ladder Polymers(2015-11) Lee, Jongbok; Rajeeva, Bharath Bangalore; Yuan, Tianyu Y.; Guo, Zi-Hao; Lin, Yen-Hao; Al-Hashimi, Mohammed; Zheng, Yuebing; Fang, Lei; Zheng, Yuebing; Zheng, YuebingThe synthesis of a carbazole-derived, well-defined ladder polymer was achieved under thermodynamic control by employing reversible ring-closing olefin metathesis. This unique approach featured mild conditions and excellent efficiency, affording the ladder polymer backbone with minimum levels of unreacted defects. Rigorous NMR analysis on a C-13 isotope-enriched product revealed that the main-chain contained less than 1% of unreacted precursory vinyl groups. The rigid conformation of the ladder-type backbone was confirmed by photophysical analysis, while the extended rod-like structure was visualized under scanning tunneling microscope. Excellent solubility of this polymer in common organic solvents allowed for feasible processing of thin films using solution-casting techniques. Atomic force microscopy and grazing incident X-ray scattering revealed a uniform and amorphous morphology of these films, in sharp contrast to the polycrystalline thin films of its small molecular counterpart.