Light microscopy of liquid-crystalline polymers

VINEY Light Microscopy of Liquid-Crystalline Polymers... 

Ferrocene-containing liquid crystalline polymers 30 have been reported from the solution polymerization of l,T-bis(chlorocarbonyl)ferrocene, terephthaloyl chloride, and methylhydroquinone in refluxing dichloromethane [38], as indicated in Scheme 10-11. With one exception, these ferrocene containing copolyesters were reported to have birefringent melts. The presence of liquid crystallinity was verified by differential scanning calorimetry (DSC), polarized light microscopy, and X-ray diffraction studies. 

As briefly mentioned earlier, thermal studies have been used in conjunction with characterization by polarized light microscopy to determine the miscibility of polymeric and small molecule liquid crystals and low molecular weight mesogens, of the same or different types of liquid crystallinity, can also be used as plasticizers or diluents for polymers, as demonstrated in a study involving side chain liquid crystalline polymers... 

It has been shown that CNTs seed the formation of oriented domains in a liquid crystalline polymer [82]. Using polarized light microscopy it was observed that the molecular alignment in large domains was homogeneous and controlled by the direction of the nanombes nucleus. CNT films have been generated by deposition... 

Thermotropic liquid crystalline PPV derivatives 43 were prepared by the coupling of dihalodialkoxybenzene and divinylbenzene in the presence of a palladium catalyst, as outlined in Scheme 47 [133]. Polarized light microscopy, as a function of temperature, showed evidence of a nematically ordered structure in the material. X-ray diffraction analysis of the pristine polymers showed them to be semi-crystalline in nature, although the crystallinity of the polymer changed dramatically upon heating above 100 °C. 

Electron microscopy revealed that the LB film had a liquid-crystalline-like structure. This means that many polymer chains were oriented parallel to the substrate plane and exhibited a preferential orientation of their backbones along the dipping direction. Absorption spectra recorded with the incident light polarized either parallel or perpendicular to the dipping direction show a maximum at 330 nm (3.76 eV) in both cases, but A and A l, the absorbances parallel and... 

The heat of transitions, AHd h) in high melting peaks, is almost independent of tc- This implies that there is always a frozen liquid crystalline phase when quenching this polymer from 400°C to room temperature. In other words, the formation of liquid crystals from the isotropic phase can proceed very rapidly. Similar observations have been reported for a polyimide LCP quenched from 350°C in air and exhibiting a fine frozen liquid crystalline texture under polarized light microscopy [64,65],... 

Since the amorphous and crystalline fractions of a high polymer cannot be separated mechanically, e.g. by filtration as for the separation of liquid solutions from crystalline complexes, the phase behaviour of polymer-salt systems is more difficult to chart than that of liquid solvents. However, many techniques, e.g, polarized light microscopy, differential scanning calorimetry, " X-ray diffraction and NMR, have been used to study the partition of the salt and the temperature dependence of phase behaviour. 

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