Synthesis And Characterization Of Poly [2,5-Bis (N/-octodecyl Piperazinyl)2-vinylterephthal Amide)] And Research On Properties Of The Concentrated Solution

Mesogen-jacketed liquid crystal polymers (MJLCPs) have the typical semi-rigidchain conformation, meanwhile, and it has large advantages in controllable synthesis,receiving more and more concern from the scientific researchers. For a long time,researchers are concentrated on thermotropic MJLCPs, to the best of our knowledge,there have no reports on lyotropic MJLCPs. As we all know, MJLCPs have the typicalsemi-rigid chain structure. which is qualified for lyotropic liquid crystals. Therefore,people do their best to make lyotropic MJLCPs in suitable conditions, unfortunately,they have not succeeded yet. Herein we designed and synthesized a novel MJLCP,making it become lyotropic liquid crystals in suitable conditions, which will bemeaningful in academic research and practical applications.This dissertation gave a detailed discussion on the synthesis and characterizationof a novel MJLCP poly[2,5-bis(N-octodecyl piperazinyl)2-vinylterephthal amide)](PNODPVTA), then discussing about effects on phase behaviors of the polymerconcentrated solution with various concentrations as well as different solvents. Twoparts of works were stated as below:1. A novel poly[2,5-bis(N-octodecyl piperazinyl)2-vinylterephthal amide)](PNODPVTA) was synthesized via conventional free radical polymerization. Itcontains long alkyl piperazinyl, which improves the solubility and stabilizes therigidity, The chemical structure of PNODPVTA was verified by~1H NMR, The phasebehaviors of the polymer were investigated by TGA, DSC, POM, the results showthat PNODPVTA exhibits good thermal stability and liquid crystalline behavior.2. Three series of PNODPVTA concentrated solution of octadecane，octadecanoland octadecanoic acid were prepared. Effects of solvents and concentrations on liquidcrystalline behavior of PNODPVTA concentrated solution were investigated by DSCand POM, on one hand, the results indicated that the crystalline melting temperatureincreased with decreasing PNODPVTA concentration， suggesting that interactionbetween polymer and solvents exists. On the other hand, birefringence disappeartemperature of PNODPVTA concentrated solution increased at first then decreasedwith decreasing PNODPVTA concentration. Compared with PNODPVTAconcentrated solutions of octadecane and octadecanol, PNODPVTA concentrated solutions of octadecanoic acid exhibited more stable liquid crystalline phase, owing tohydrogen bond formed between PNODPVTA and octadecanoic acid, which isbeneficial to stabilize the liquid crystalline phase. To our surprise, PNODPVTAconcentrated solutions of octadecanoic acid still display liquid crystallinity whenPNODPVTA concentration decreased to10%, in addition, PNODPVTA concentratedsolutions of octadecane and octadecanol display liquid crystallinity whenPNODPVTA concentration above45%and50%respectively. Indicating interactionsbetween the polymer and various solvents are different, exerting different effects onphase behavior of PNODPVTA concentrated solutions.