A series of waterborne cationic-nonionic polyurethanes surfactants (CPUS) was prepared through prepolymerization method and their structures were investigated by FTIR and 1H-NMR.The effects of N-methyldiethanolamine (MDEA) concentration on the surface tension

critical micelle concentration

rheology property

micelle size

micropolarity and aggregation behaviors of CPUS were studied by DLS

surface tension analysis

steady state rheological analysis and fluorescence analysis.TEM results showed that CPUS micelles displayed as core-shell spheres.It was also found that average micelle particle size and polydispersity index of CPUS solutions decreased with increasing MDEA concentration.While the surface tension and critical micelle concentration (CMC) decreased first and then increased

the lowest of which were 1.99 g/L and 39.54 mN/m.When the CPUS concentration was lower than CMC

the light scattering intensity was very low and changed slowly with CPUS concentration.However

the light scattering intensity displayed a gradually increasing tendency when the CPUS concentration was greater than CMC.Meanwhile

the aggregation number of CPUS micelles increased greatly.The viscosity of CPUS solution increased with increasing MDEA concentration

as well as the interactions among micelles increased

while the pseudoplastic behavior was enhanced.In addition

fluorescence spectrometry showed that I1/I3 values decreased from 1.8 to 1.3 and I338/I334 increased from 0.5 to 1.7

suggesting that the hydrophobic groups tended to aggregate and form hydrophobic microdomains

and pyrene molecules transfered from the aqueous polar phase to micellar interphase.Furthermore

the micelle micropolarity and the difficulty with micelle formation decreased first and then increased as increasing MDEA concentration.