level: THE LIQUID CRYSTALLINE STATE
Questions and Answers List
level questions: THE LIQUID CRYSTALLINE STATE
| Question | Answer |
|---|---|
| It is the liquid crystalline phase | • Mesophase |
| Partly solid and partly liquid, tend to flow like liquid under extreme conditions | • Plasma |
| TYPES OF PLASMA | • SMECTIC • NEMATIC • CHOLESTERIC |
| Smectic | • Soap-like / grease-like • Rotate in one axis • Mobile in 2 directions • Most pharmaceutically important |
| Nematic | • Thread-like • Rotate in one axis • Mobile in 3 directions |
| Significance of Smectic | • Solubilization of water insoluble materials will enchanced physical stability of emulsions |
| What are the molecules that form mesophases? | • Organic • Elongated and rectilinear shape • Rigid • Possess strong dipoles and easily polarizable |
| Methods of Formation | • Lyotropic • Thermotropic |
| Liquid crystals are formed using solvents | • Lyotropic |
| Liquid crystals are formed using heat | • Thermotropic |
| Examples of Thermotropic | • Cholesteryl benzoate (145C solid, 179C liquid state turbid) discovered by Reinitzer (1888) |
| • A mesophase formed from the gaseous state where tha gas is held under a combination of temperatures and pressures that exceed the critical point of substance | Supercritical fluids |
| Significance of Supercritical Fluids | • Extraction • Crystallization • Preparation of formulations (Polymer mixtures, micro- and nanoparticles) • Reduces toxicity of gases • Reduced need for hazardos solvents |