Synthesis And Electric Field-induced Orientation Of Pyrene-labeled Diblock Weak Polyelectrolyte

Block polyelectrolyte is one of an important part of being block copolymer.Block polyelectrolyte in the dilute solution, with the changing of the consist of blockcopolymer, the pH, the polymer concentration, temperature, salt concentration andother factors, also its conformation and self-assembling behavior will be changed; insolution, the changing of self-assembling has a great potential application value indrug delivery, water purification, oil exploration, etc.. Polyelectrolyte solutions inelectric field environment, the solution of charged ions and polyelectrolyte willmigrate under the action of electric field; electrostatic coupling force is weak whichgenerated between polyelectrolyte and ions of opposite charge; so in a certain electricfield strength, polyelectrolyte molecular chain will follow the electric field, so as toform the electric field formed in a direction extending along with the molecular chainconformation. Block polyelectrolyte for contains charge block, the blockpolyelectrolyte has both features of block copolymer and polyelectrolyte, a chargedpolyelectrolyte block chains can be induced in the electric field along the fieldstretching direction orientation. Although the field-induced small organic moleculeshave been reported, it’s still a problem for researching the conformation of blockpolyelectrolyte in solution under the induction of electric field. Usingfluorescent-labeled to study the conformation of block polyelectrolyte moleculeschain in the solution to get real feedback from the molecular level changes in thepolymer chain. This work will be designed and used atom transfer radical (ATRP)methods to separately synthesize nonionic’s block polyelectrolyte which has bothpolycation and pyrene fluorescent-labeled. By adjusting applied electric field strength,pH value, polymer concentration, temperature, applied salt concentration compositionetc. to achieve adjust and control of conformation of pyrene labeled Blockpolyelectrolyte in aqueous solution. The study has a great importance on field-induceddeposition of functional block super-molecular polyelectrolyte films.The details of this thesis are as follows:(a) design and use ATRP polymerizationmethod to synthesize Py-PHEMA-b-PDMAEMA successfully. And also using1HNMR and GPC to character, came to a conclusion that synthesizedPy-PHEMA-b-PDMAEMA has an exact chemical constitution and its molecular weight distribution is narrow.(b) The study of the behavior ofPy-PHEMA-b-PDMAEMA molecular chain induced by eclectic filed. Experimentalresults show that Py-PHEMA-b-PDMAEMA molecular chain under the influence ofelectric filed, the conformation of curl tends to be extended along with the electricfiled orientation; it will help the induction of electric field orientation of molecularchain with decrease the pH value and properly increase salt concentration, if increasethe viscosity of the solvent, then it is not conducive to field-induced orientation in thesolution.