Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 5. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Model Compounds with Short Fluorocarbon Segments
摘要:
5-[[[2',5'-Bis[(4"-n-((perfluoroalkyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-enes with short fluorocarbon segments were polymerized by ring-opening metathesis polymerization in THF at room temperature using Mo(CHCMe2Ph)(N-2,6-'Pr2Ph)(O'Bu)(2) as the initiator. Although hydrocarbon and fluorocarbon segments as short as three methylenic units each induce smectic layering in the corresponding 2,5-bis{[4'-(n-(perfluoroalkyl)alkoxy)benzoyl]oxy}toluene model compounds, the polymers require at least eight and three, or five and four methylenic units in the hydrocarbon and fluorocarbon segments, respectively, to organize into smectic layers; polymers with shorter hydrocarbon and/or fluorocarbon segments are nematic.
Shape memory main-chain smectic-C elastomers are described, as are methods for their preparation and monomers used in such methods. The elastomers are prepared by hydrosilylation of a reaction mixture including a liquid crystalline diene, a crosslinking agent, and a bis(silyl hydride) compound. The elastomers exhibit shape-memory properties and spontaneously reversible shape changes. They are useful for fabrication of shape memory articles including, for example, implantable medical devices, contact lenses, reversible embossing media, and Fresnel lenses.
Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 1. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Analogs with Hydrocarbon/Fluorocarbon Substituents
作者:Stephen V. Arehart、Coleen Pugh
DOI:10.1021/ja963687p
日期:1997.4.1
contrast to their hydrocarbon analogues which exhibit only nematic mesophases, poly5-[[[2‘,5‘-bis[(4‘‘-(n-(dimethylsiloxyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s and their low-molar-mass model compounds exhibit smectic C mesophases. Since nematic liquidcrystals can be forced into layers by terminating their hydrocarbon substituents not only with fluorocarbon segments but also
Induction of Smectic Layering in Nematic Liquid Crystals Using Immiscible Components. 5. Laterally Attached Side-Chain Liquid Crystalline Poly(norbornene)s and Their Low Molar Mass Model Compounds with Short Fluorocarbon Segments
作者:Aaron C. Small、Coleen Pugh
DOI:10.1021/ma0113430
日期:2002.3.1
5-[[[2',5'-Bis[(4"-n-((perfluoroalkyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-enes with short fluorocarbon segments were polymerized by ring-opening metathesis polymerization in THF at room temperature using Mo(CHCMe2Ph)(N-2,6-'Pr2Ph)(O'Bu)(2) as the initiator. Although hydrocarbon and fluorocarbon segments as short as three methylenic units each induce smectic layering in the corresponding 2,5-bis[4'-(n-(perfluoroalkyl)alkoxy)benzoyl]oxy}toluene model compounds, the polymers require at least eight and three, or five and four methylenic units in the hydrocarbon and fluorocarbon segments, respectively, to organize into smectic layers; polymers with shorter hydrocarbon and/or fluorocarbon segments are nematic.