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Fakultät für Biologie, Chemie und Geowissenschaften

Makromolekulare Chemie I: Prof. Hans-Werner Schmidt

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Flüssigkristalline Polyester
Ansprechpartner: Hans-Werner Schmidt, Reiner Giesa
A fiber of an LC polyester shows the typical 'woodlike' fracture indicating high modulus and tenacity
Several synthetic strategies for improving the solubility and lowering the melting transitions of thermotropic liquid crystalline polymers (TLCP) have been developed. In general this can be achieved by structural modification of the fully aromatic building blocks of the polymer chain without sacrificing the chain stiffness. Four important structural modifications can be used for the synthesis of processible, para-like aromatic TLCPs: i) non-coplanar monomers, ii) bulky side groups, iii) the introduction of kinked, bent or crankshaft monomers, and iv) the combination of all these structures in a copolymerization. Non-coplanar monomers (i) such as 2,2'-substituted biphenols, have proven to be especially effective in lowering transition temperatures while preserving maximum chain stiffness. Copolyesters containing this kind of monomers show dramatically decreased transition temperatures and enhanced solubilities compared to unsubstituted polymers. Melting temperature can also be reduced by using derivatives with bulky lateral substituents or flexible side chains. With a combination of such structural modifications in copolymers, it is possible to suppress the crystallinity in TLCPs resulting in materials which preserve the nematic order below the glass transition temperature and form nematic glassy solids

Publikationsliste

Grasser, W.; Schmidt, H.-W.; Giesa, R.: Thermotropic liquid crystalline copolyesters with non-coplanar biphenylene units tailored for blend fiber processing with PET, Polymer, 42, 8529-8540 (2001)
Reichelt, N.; Schulze, U.; Schmidt, H.-W.: Synthesis and characterization of ABA-triblock copolymers with polystyrene and main-chain liquid crystalline polyester segments, Macromolecular Chemistry and Physics, 198, 3907-3930 (1997)
Schulze, U.; Reichelt, N.; Schmidt, H.-W.: Block Copolymers with Liquid Crystalline Segments, Macromolecular Symposia, 117, 131-140 (1997)
Skrifvars, M.; Schmidt, H.-W.: Unsaturated Para-Linked Aromatic LC Polyesters: Thermotropic and Lyotropic Systems, Journal of Applied Polymer Science, 55, 1787-1795 (1995)
Mather, P.; Grizzutti, N.; Heffner, G.; Ricker, M.; Rochefort, W.E.; Seitz, M.; Schmidt, H.-W.; Pearson, D.S.: Synthesis and characterization of a semiflexible liquid crystalline polyester with a broad nematic region, Liquid Crystals 17(6), 811-826 (1994)
Lee, S.; Oertli, A.G.; Gannon, M.A.; Liu, A.J.; Pearson, D.S.; Schmidt, H.-W.; Fredrickson, G.H.: Phase Behavior of Liquid Crystalline Polymer/Model Compound Mixtures: Theory and Experiment, Macromolecules, 27, 3955-3962 (1994)
Motamedi, F.; Jonas, U.; Greiner, A.; Schmidt, H.-W.: Preparation and characterization of fibres from a thermotropic liquid crystal polyester with non-coplanar biphenylene units, Liquid Crystals 14(4), 959-970 (1993)
Skrifvars, M.; Schmidt, H.-W.: Synthesis and LC-Behavior of Unsaturated Para-linked Aromatic Polyesters by Interfacial Polycondensation, Polymer Preprints of the American Chemical Society, 34(2), 696 (1993)
Greiner, A.; Rochefort, W.E.; Greiner, K.; Heffner, G.; Pearson, D.S.; Schmidt, H.-W.: Melt and Solution Properties of Para-linked Aromatic LC-Polyesters, Integration of Fundamental Polymer Science and Technology, Elsevier Applied Science Vol. 5, 258-268 (1991)
Land, H.-T.; Hatke, W.; Greiner, A.; Schmidt, H.-W.; Heitz, W.: Synthesis of arylsubstituted monomers for high-performance polymers, Makromolekulare Chemie Rapid Communications, 191, 2005-2016 (1990)
Heitz, W.; Schmidt, H.-W.: Soluble LC polyesters and their blend behavior, Makromolekulare Chemie - Macromolecular Symposia, 38, 149-160 (1990)
Hohlweg, M.; Schmidt, H.-W.: Thermotropic para-linked aromatic polyesters containing 1,1’-binaphthyl-4,4’-ylene units, Makromolekulare Chemie Rapid Communications, 190, 1587-1593 (1989)
Schmidt, H.-W.: Influence of Lateral Substituents on Thermal Behavior and Solubility of Aromatic LC-Polyesters, Makromolekulare Chemie - Macromolecular Symposia, 26, 47-55 (1989)
Schmidt, H.-W.; Guo, D.: Synthesis and properties of para-linked aromatic polyesters containing 2,2’-dimethylbiphenylylene units, Makromolekulare Chemie Rapid Communications, 189, 2029-2037 (1988)
Gilli, J.M.; Schmidt, H.-W.; Pinton, J.F.; Sixou, P.; Thomas, O.; Kharas, G.; Blumstein, A.: Electro-hydrodynamic Instabilities in Main Chain Thermotropic Liquid Crystalline Polyesters, Molecular Crystals Liquid Crystals, 102, 49-58 (1984)

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