Synthesis Of Amphiphilic Polymers By One-Pot And Self-assembly Behavior Research

In recent years, with the rapid development of macromolecular structure andcomposition of the design field, more and more people focus on the combination ofdifferent polymerization methods synthesis strategy to achieve the molecular structureand function design. Wherein the synthetic amphiphilic polymers occupy a majorposition of the molecular structure of such polymers include of: a block、graft、centipede、star、dendritic and hyperbranched like. Due to a variety of aggregation ofone-pot or in conjunction with the preparation of the specific structure of the polymersynthesis technology has been widely studied and applied. Especially in thepreparation of the special structure or functional aspects polymers. Therefore, thispaper were used click chemistry、ATRP、enzymatic ring-opening polymerization andtransesterification four polymerization reaction system through different strategies tosynthesis the structure of the particular various amphiphilic block or graft polymers.In the second chapter，bifunctional initiator was synthesized by small moleculesthrough a simple two-step modified simultaneously to trigger ATRP and clickchemistry reactions. Furthermore use the monomersof ATRP reaction hydroxyethylmethacrylate (HEMA) containing a terminal hydroxyl group as initiator for theenzymatic caprolactone ring-opening polymerization, this strategy achieve a one-potsynthesis by three different polymerization reaction to obtain PEG-b-PHEMA-g-PCL(polyethylene-hydroxyethyl methacrylate-polycaprolactone), then NMR、FT-IR andGPC tests were conducted to characterize the polymer’s structure and composition,DLS and TEM test showed its polymer micelles and proved that the hydrophobicsegment PCL graft proportional to the particle size and different critical micelleconcentration on the aqueous phase in micelles formed by self-assembly and the sizewas slightly ball.In the third chapter, use the transesterification reaction of the polymer backboneside chain for functional modification, and further modified by graft reaction of the polymer backbone, PHEMA was given a side chain containing both have (PEG) ashydrophilic segment and (PCL) as hydrophobic segment. Polymer structure andcomposition were characterized by NMR、FT-IR and GPC, DLS and TEM testsshowed micelles self-assembled in the aqueous phase and the formation of smalluniform size.In the fourth chapter,Click Chemistry and ATRP reaction by one-pot to preparePEG-b-PHEMA polymer backbone, then use its side chain to further graftmodification His (histidine),obtain the polymer PEG-b-PHEMA-g-His.NMR、FT-IRand GPC characterized its structure and composition. Because of the side chainimidazole group that histidine had, imidazole ring unsaturation on a nitrogen lonepair of electrons, so its effect on pH-sensitive protonation and deprotonation toachieve. Therefore, the already synthesized PEG-PHEMA polymer backbone graftedHis(histidine)can change to pH-sensitive polymer. When the pH>7,histidinedeprotonated and polymer get amphiphilic to form micelles; but when pH <6, theprotonation of histidine made the polymer to be completely hydrophilic polymer,sothe micelles destroy. DLS and TEM test morphology of the polymer micelles, theresults show that with the increase of the rate of histidine resulted the polymer micelleparticle size decreases, in addition acid-base titration experiments and drugs releasecharacterized the pH-sensitive of polymer. The results showed that pH-sensitiveamphiphilic polymer has been successful prepared..