Synthesis And Self-assembly Of The Highly-Branched Amphiphilic Block Polyethers

Based on the widely application prospect of the block polymers in the practical life, such as the nanometer material, biological medicine, oilfield chemistry, etc., a series of amphiphilic highly-branched block copolymers were designed. A series of new highly-branched block polyethers with different number and proportion of blocks were synthesized via anion ring-opening polymerization of propylene oxide(PO) and ethylene oxide(EO), using phenol-amine resin(PA) as the initiator. The molecular structures were con?rmed by end group analysis, FT-IR and 1H NMR.The rheological properties of the several kinds of highly branched block polyethers were determined by the advanced rheometer. On the whole, all results reflected that the rheological properties of such highly-branched polyethers follow the regular rules of polymer systems.But compared with the same kind of linear polymers, the significant difference was the low melt viscosity. Besides, under the experimental conditions, the differences of rheological properties between each other were showed obviously.The properties of block polyethers in aqueous solution(the critical micelle concentration(CMC), aggregation number, morphology and size) were studied by the automatic tensiometer,fluorescence spectroscopy(pyrene was used as probe), ultraviolet visible spectrophotometer(UV-vis) spectra, transmission electron microscope(TEM) and dynamic light scattering(DLS). The CMC of polyethers aqueous solution presented a wide range, and the scope of CMC corresponded to the content of EO. Moreover, the proportion of PA had a great effect on the properties of the whole polymer molecules, and the number of blocks was a critical factor to the process of self-assembly. For such special highly-branched polyethers with multi terminated-OH groups, due to the effect of hydrogen-bond, the formation of structured water would prompt the polymers to tend to form the unimolecular micelles firstly, and then the unimolecular micelles further aggregated into large micelles, which answer the unimolecular micelle aggregate(UMA) mechanism.Cosolvent and kinds of surfactant had also apparent influences on the self-assemblyAdditionally, TEM and DLS demonstrated that the size of the micelles could be changed by the addition of alcohols, but the aggregation morphology would not change. In addition, the moderate amount of hydrophilic surfactants(nonionic PVP, anionic HAPAM and cationic C8H15N2BF4 surfactant) would promote the molecular association(it reduced the CMC value in aqueous solution). Nevertheless, the molecular association would be inhibited if the surfactants became excessive. In addition, for the hybrid system of PA60-3-40 and Gemini properties of micelles in aqueous solution.The type and content of cosolvents had a significant effect on the CMC of polyether micelles: the CMC first decreased and then increased with increasing the content of n-pentanol, but with an increase of ethylene glycol concentration,there was a durative decrease of the CMC; the micellization became more spontaneous in the presence of cosolvents with more hydroxyl groups; the CMC did not monotonically increase or decrease with the increasing carbon chain length of aliphatic monohydric alcohols.16-m-16 hydrophobic surfactant, 16-m-16 played a leading role in the process of the molecular association.