Study On Preparation&Solution Properties Of Amphiphilic Hyperbranched Polymers

Hyperbranched polymers are a kind of three-dimensional structure, highlybranched macromolecules. They also have many characteristics, such asmultiterminal group, low melting point, better rheology, excellent solubilityperformance and higher reactivity. Compared with dendritic polymers, thesynthesis process of hyperbranched polymers does not require strictprotection/de-protection. So much attention has been given to the research ofhyperbranched polymers.Hyperbranched polymers have many active end groups, and many kinds ofhyperbranched polymers with special performance can be obtained through theend group functionalization. Amphiphilic hyperbranched polymers are a kind ofnew amphiphile with special structure and properties. They can be synthesizedby the oleophilic/hydrophilic modification of hyperbranched polymers. They aredifferent from the traditional surfactant and linear amphiphilic macromolecules.The special molecular structures of amphiphilic hyperbranched polymers showspecial unimolecular micelles performance and self-assembly properties in thesolution. The research of amphiphilic hyperbranched polymers in guestencapsulation and self-assembly has become one of the hot spot of polymerscience.The different generation hydroxyl-terminated hyperbranched poly（amine-ester） was synthesized by the esterification reaction in which succinicanhydride, diethanolamine, trimethylol propane were used as raw materials. Theoptimum synthesis conditions, such as reaction time, reaction temperature anddosage of catalyst, were explored by single-factor experimental. The resultsshowed that the reaction temperature was120℃, the reaction timewas8h,dosage of catalyst was3%（based on total mass of AB₂monomer）, regulating themolar ratio of trimethylolpropane and AB₂monomer was1:3,1:9,1:21,1:45, respectively. The different generation hydroxyl-terminated hyperbranchedpolymers can be obtained. The molecular structures of polymers werecharacterized by FTIR,¹H NMR and¹³C NMR. The results indicated that theproducts were in conformity with expected structures. The solubilityperformances of products in water and organic solvents were studied. The resultsshowed that the number of terminal hydroxy had a great influence on thesolubility performances of the products.A series of hyperbranched polymer surfactant （HBP-C8, HBP-C12andHBP-C16） was synthesized by the reaction between hydroxyl-terminatedhyperbranched polymers （HBP） and octanoyl chloride, lauroyl chloride andpalmitoyl chloride, respectively. The structure of obtained polymers wascharacterized by FTIR,¹H NMR,¹³C NMR and GPC. The results indicated theobtained products had the core-shell structure, and the relative molecular mass ofthe product distribution was wide. The thermal property of polymers wasinvestigated by DSC and TGA. It was found that the thermal performance ofhyperbranched polymer surfactant was strongly influenced by the length of endalkyl chain. Surface tension activity of hyperbranched polymer surfactant wasanalysed by surface tension method and the critical micelle concentration （CMC）of products was investigated by ultraviolet spectrophotometry. The resultsshowed that hyperbranched polymer surfactant displayed better surface activity,which can effectively reduce the surface tension of the water. Hyperbranchedpolymer surfactant had a lower critical micelle concentration and displayedsingle molecular micellar properties, which can package hydrophilic smallmolecule in relatively low concentration.A series of amphiphilic hyperbranched polymers was synthesized by thereaction between different generation hydroxyl-terminated hyperbranchedpolymers （HBP） and palmitoyl chloride. The products of high graft rate can beobtained by optimizing synthesis conditions: the ice-water bath, the mixedsolvent （the volume ratio of chloroform and pyridine was1:1）, the graft rate ofproducts was above95%. The structure of obtained polymers was characterizedby FTIR,¹H NMR,¹³C NMR and GPC. The results showed the obtainedpolymers had amphiphilic structure. The relative molecular mass was increasingwith the increase of the degree of branch and the relative molecular mass distribution was wide. The thermal property of polymers was investigated byDSC and TGA and it was found that the thermal property of products wasstrongly influenced by the size of the hydrophilic kernel.The obtained amphiphilic hyperbranched polymers have hydrophilic coreand hydrophobic shell, which can display special self-assembly performance inselective solvents and reverse micellar property in organic solvent. In this paper,tetrahydrofuran （THF） was chose as solvent, the self-assembly performance ofamphiphilic hyperbranched polymers was investigated by transmission electronmicroscopy （TEM） and scanning electron microscopy （SEM）. The resultsshowed that amphiphilic hyperbranched polymers with different size hydrophilickernel can form unimolecular micelles, multimolecular micelles and polymervesicles. The methyl orange was selected as the target molecule, and the phasetransfer behavior was studied by the uv-vis spectrophotometry. The obtainedamphiphilic hyperbranched polymers can accommodate hydrophilic guestmolecules methyl orange, and the guest encapsulation capacity had correlationwith the size of the amphiphilic hydroxyl core and pH of the system.