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Functional macromolecules synthesized from acetylenic monomers

Authors Jim, Ka Wai
Issue Date 2010
Summary Advancements in technology are directly associated with the developments of new materials and exploration of new polymerization reactions for the synthesis of new polymers with novel structures is a fundamentally important area in macromolecular science. Polymerizations of acetylenic monomers afford electronically unsaturated polymers that are difficult to obtain by the conventional vinyl polymerization. In other words, the acetylenic monomers are a group of versatile building blocks for the construction of functional polymers and the acetylenic polymerizations are useful tools for the development of specialty materials. In this thesis, new methodologies for the construction of linear and hyperbranched acetylenic polymers with unique properties are explored. Homo- and co-polycyclotrimerizations of arylene bipropiolates proceed regioselectively in reflux N,N-dimethylformamide, giving hyperbranched poly[1,3,5-tri(aroxycarbonyl)henylene]s (hb-PTACPs) with high molecular weights (Mw up to ~8.3 x 105) in high yields (up to 82%). The resulting polymers possess perfect 1,3,5-regiostructures and high degrees of branching (DB ~88%). They exhibit high thermal stability with little weight losts when heated to 390 ℃. The polymers are highly transparent and show high refractive indices (RI = 1.6225−1.681) with very low optical dispersion (D’ = 0.00097). The polymer films can be readily cross-linked by UV irradiation, enabling readily generation of negative photoresist patterns. Incorporation of ferrocene unit in the polymer structure can further enhance the RI value and ceramization of the organometallic hb-PTACPs at high temperature under nitrogen furnishes magnetoceramics and patterns with high magnetization and resolution. Alkyne polyhydrothiolations of dithiol and arylene bipropiolates mediated by amine proceed smoothly at room temperature in a regioselective fashion, furnishing sole anti-Markovnikov products of poly(vinylenesulfide)s with high molecular weights (Mw up to 32300) and high stereoregularities (Z content up to 81.4%). The polymers are optically transparent, allowing almost all visible and near IR lights to transmit through. The high sulphur contents of the polymers endow them with high refractive indices in the wavelength region of 500−1700 nm as well as high Abbé number and low optical dispersions. The RI values can be further enhanced by metal complexation. UV irradiation of the polymer films cross-links the polymers, generating fluorescent photopatterns. Homopolymerizations of tetraphenylethene-containing diacetylenes catalyzed by CuCl in o-dichlorobenzene produce linear polyyne in high yields. The polymers are soluble and enjoy high thermal stability. They are practically non-emissive when molecularly dissolved in good solvents, and become highly emissive when aggregated as nanoparticle suspensions in poor solvents or fabricated into thin films in the solid state, demonstrating a novel phenomenon of aggregation-induced emission. The refractivities of the polymer films can be modulated and their thin films can be cross-linked by UV irradiation which give fluorescent patterns with high resolutions. Ferrocene-functionalized disubstituted polyacetylenes are obtained in high yields by Cu-catalyzed click reaction of azide-carrying polyacetylenes with ethynylferrocene. Pyrolysis of the polymers under nitrogen furnish magnetic ceramics with high magnetizability. Poly(diacetylene)s carrying menthyl pendant groups are obtained in high yields with high molecular weights using WCl6−Ph4Sn. The polymers show strong CD backbone absorptions in both solution and aggregate states, suggesting that the chiral menthyl groups have induced the polymer strands to rotate in a predominant screw sense. Photopatterns can be obtained by photooxidation of the polymer films by UV light in air. Finally a series of acetylenic polymers containing AIE luminogens are synthesized and their emission and light refractivity are investigated.
Note Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2010
Language English
Format Thesis
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