| Polyether block copolymer as a typical macromolecular surfactant,is rich in its structure can be designed.Synthesis can be controlled,such as the length of each segment,the ratio of EO/PO and molecular weight of block copolymer,etc.The solubility of PEO and PPO in water with a temperature-dependent,in addition to the diversity of solvent system,greatly enriched in the solution of this type of block copolymer self-assembly in the formation of supramolecular aggregates of the study. PEO and PPO block polymer composed of surfactants have been widely used as emulsifying,wetting,solubilization and so on.There are two types of the linear triblock copolymers:Pluronic and Pluronic-R type,the former often is expressed as (PEO)n(PPO)m(PEO)n,while the latter is(PPO)m(PEO)n(PPO)m,in which n and m, respectively,ethylene oxide(EO) and propylene oxide(PO) number of units.PPO block is hydrophobic and PEO is hydrophilic.It may affect their aggregation in aqueous solution and application that the concentration of the aqueous system or temperature,structural parameters(such as block copolymer molecular weight and the ratio of EO/PO),chain conformation(PEO-PPO-PEO or PPO-PEO-PPO),etc..Polyether macromolecular surfactant has been an interesting research because of its various structure and aggregation behavior.Several kinds of amphiphilic polyether copolymers have been synthesized in our laboratory,and the properties such as aggregation behavior and interfacial properties have been investigated by experimental methods and molecular simulation,such as dissipative particle dynamics (DPD) and mesoscale dynamics(MesoDyn) simulation methods.On the base of these researches,the physical and chemical properties of branched polyethers(denoted as AE82 and AE83,which were synthesized via anionic polymerization in our lab) are studied by surface tension,steady-state fluorescence measurements and transmission electron microscopy(TEM),etc.Moreover,the dispersion of carbon nanotubes(CNTs) by branched polyether in aqueous solution is investigated.On the basis,the impact of CNTs/polyether dispersion system is studied when waterborne epoxy resin(E570) is applied as varnish coating.This thesis includes four topics.In the first section,the aggregation behavior in solution and application of block copolymer are summarized.The properties and applications of carbon nanotubes are also presented.And the dispersion of carbon nanotubes by amphiphilic molecules is expatiated.In the second section,the aggregation behaviors of AE82 and AE83,in aqueous solutions were investigated by surface tension,steady-state fluorescence,TEM and the surface dilational viscoelasticity.For comparison,a commercially available block copolymer,Tetronic 1107(T1107) and Tetronic 90R4(T90R4),were also studied.It is found that both the efficiency and the effectiveness of AE82 and AE83 to lower the surface tension of water are higher than those of T1107 and T90R4.The Tmax values of them are higher and the Amin values of them are lower than that of T1107 and T90R4.From fluorescence measurement,it can be conclude that the order of micro-environment hydrophobicity(AE82＞AE83) and the order of ability to lower the surface tension of water(AE82＞AE83).This is consistent to the conclusions of surface tension measurement.TEM observations reveal that,with increasing concentration,AE82 molecules tend to form a large micelle,while AE83 tend to form a new micelle.In the third section,the ability of dispersing carbon nanotubes(CNTs) in aqueous solutions by branched polyether(AE82 and AE83) was investigated by UV-vis-NIR, Raman spectra and HRTEM observations.For comparison,T1107 and T90R4 were also studied.From the experiments,it was found that AE82 and AE83 can get stable CNTs dispersions for three months while they were not the case for T1107 and T90R4. It is difficult to disperse CNTs by T90R4 because of PPO-PEO type.T1107 is PEO-PPO type,but its low PO%and poor hydrophobicity are not enough to have hydrophobic interaction with the sidewall of CNTs.Although AE82 and AE83 have similar molecular structure,the dispersion by AE82 is better than by AE83.Because AE82 has higher Tmax value,stronger hydrophobic and better ability to lower the surface tension of water.It is easier to inteact with the sidewall of CNTs by absorption. Its higher EO%also can stop from the aggregation of CNTs.The absorbance of UV-vis-NIR absorption spectra of CNTs/AE82 system shows that with the increased concentration of AE82 aqueous solution,the concentration of dispersed CNTs increased,and then decrease.But to CNTs/AE83 system,with the increased concentration of AE83 aqueous solution,the concentration of dispersed CNTs increased sharply,and then rose up slowly.The mechanism of dispersing CNTs by different copolymers can be rationalized,that is,when mixed with CNTs,the PO groups would interact with the sidewall of CNTs while the EO groups extend into water and hence create steric repulsion.In the forth section,we compared with the different affection of water system, multi-branched polyether aqueous solution system and CNTs/polyether system when waterborne epoxy resin(E570) is applied as varnish coating.Multi-branched polyether(AE82 and AE83) can shorten the curing time of E570,and CNTs can improve the rigidity of E570 as varnish coating.Curing time is increased with the curing temperature to drop rapidly when the temperature reaches 50℃,the curing time has no change with temperature.
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