Supramolecular main-chain liquid crystalline polymers and networks with competitive hydrogen bonding: a study of flexible bis-acids and a mixture of flexible mesogenic bispyridyls and flexible polypyridyls Steven R. Friday, Richard F. Miesen and Kurt N. Wiegel Department of Chemistry, University of Wisconsin, Eau Claire, Eau Claire WI Background Materials Used Liquid Crystals Materials that exhibit long-range and some short-range directional ordering in a fluid state. Composed of mesogens (shaped molecules) and flexible spacers Different types of mesogens based on molecular shape (calamitic: rod- shaped) Molecular Self-assembly Through Hydrogen Bonding Non-covalent interactions formed between two molecules through a hydrogen-bond resulting in a larger “associated” molecule ObservationsAcknowledgements Complexes synthesized through standard melt-complex methodology DSC data determined on a Mettler-Toledo STAR e1 DSC at 10 ° C/Min heating rate unless otherwise noted Optical micrographs were measured using a Mettler-Toledo FP82 Hotstage Mounted on an Olympus BHT polarizing light microscope at a 10 ° C/Min heating rate unless otherwise noted This work was funded by the National Science Foundation (Award Number ) and UW-EC Office of Research and Sponsored Programs and Matthew Hammers for his contributions to the project Mesogenic Networks Combine characteristic of networks and liquid crystals Couple physical deformations with liquid crystalline phase behavior Thermoreversability through hydrogen bonding would introduce lability and the ability to reorganize to these characteristics Thermal Analysis Wiegel Research: Careening from catastrophe to catastrophe since 2000 Results/Observations Supramolecular Networks Networks vary clearing compositions based on Functionality of crosslinking agents and flexibility (hydrogen bond donors and acceptor groups) Generally: Increasing from 3EOBSB to 4EOBSB increases clearing compositions by increasing flexibility Increasing from 4EOBSB to 5EOBSB decreases clearing compositions, likely from a dramatic melting point decrease Increasing functionality of networking agents increases clearing compositions Increasing flexibility of hydrogen bond donors increases clearing compositions Enantiotropic behavior observed only in some 5EOBBA systems Smectic phases observed in systems with high degrees of flexibility Complex Series Clearing Composition Clearing Temperature TrendSmectic Clearing CompositionNotes 4 EOBBA/3EOBSB/2PD22.5%Decrease with loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/3EOBSB/3PD30%Decrease with loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/3EOBSB/4PD32.5%Decrease with loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/4EOBSB/2PD42.5%Decrease with Loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/4EOBSB/3PD50%Decrease with Loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/4EOBSB/4PD 60%Decrease with Loadingn/aMonotropic on cool, no smectic phase 4 EOBBA/5EOBSB/2PD32.5%Decrease with loading10%Enantiotropic up to 10% 4 EOBBA/5EOBSB/3PD32.5%Decrease with loading5%Enantiotropic at all concentrations 4 EOBBA/5EOBSB/4PD 35%Decrease with loading5%Enantiotropic at all concentrations 5 EOBBA/3EOBSB/2PD25%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/3EOBSB/3PD35%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/3EOBSB/4PD 52.5%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/4EOBSB/2PD32.5%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/4EOBSB/3PD40%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/4EOBSB/4PD 55%Decrease with loadingn/aMonotropic on cool, no smectic phase 5 EOBBA/5EOBSB/2PD %Decrease with loading10%Enantiotropic at all concentrations 5 EOBBA/5EOBSB/3PD30-40%In progress10%Enantiotropic at all concentrations 5 EOBBA/5EOBSB/4PD35%In progress10%Enantiotropic at all concentrations 4EOBBA/5EOBSB/10%3PD 4EOBBA/3EOBSB