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Browsing by Author "Lee, Sang-Hun"

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    Supramolecular architectures: macrocycles, catenanes and polyrotaxanes
    Lee, Sang-Hun (Virginia Tech, 1996-12-05)
    Polyrotaxanes are molecular composites consisting of three components: linear polymers, bulky stoppers at the ends of polymer chains and macrocycles threaded by the polymers. A series of tetraarylmethyl derivatives as blocking groups were synthesized. Using tris(p-ten-butylphenyl)( 4-hydroxyphenyl)methane a new blocking groupfmitiator (BO(mit) was synthesized. The BG(mit's ability of blockingfmitiation in free radical polymerizations was established by polymerization of styrene. As cyclic components, aliphatic crown ethers (30-crown-lO, "42-crown-14" and "6O-crown-20") were synthesized by multi-piece combination methods. The purification of the crown ethers was achieved by treatment with poly(methacryloyl chloride), column chromatography and recrystallization; by NMR in DMSO-d₆ the purity of the products was demonstrated. The 42-crown-based [2]catenane was isolated while synthesizing "42- crown-14" and characterized in terms of its physically interlocked structure. Two new hydrocarbon-based macrocycles were prepared by two-piece combination method.