Investigation of the bulk and solution properties for multiblock polyethers

Three kinds of multiblock polyethylene oxide-polypropylene oxide (PEOm-PPOn for short) were synthesized using ethylene glycol as the initiated core via the living anionic polymerization. Respectively, the multiblock polyethers were named E340, E540, and E740 based on the block number (3, 5, 7) and the content of ethylene oxide (EO, 40 wt%), which were confirmed by the Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC). Moreover, their bulk and solution properties, including dynamic modulus, rheological characteristic, viscosity, aggregation behavior, surface tension, steady-state fluorescence, solubility, and microemulsion performance were determined. The test results of rheological properties showed that these multiblock copolyethers behaved as the pseudo-plastic non-Newtonian fluids. Furthermore, it was found that their solubility and surface tension were gradually decreased with an increase of block numbers. Nevertheless, the dynamic modulus tended contrary trends. Research on the aggregation and micro-emulsion properties in aqueous solutions indicated that the value of critical micelle concentration (CMC) increased, and meanwhile the ability of solubilization and micro-emulsion formation deteriorated with increasing block numbers. In conclusion, their aggregation mechanism in aqueous solution was also given.

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