Study on the association behavior of a hydrophobically modified polyacrylamide in aqueous solution based on host-guest inclusion

Abstract

A quantitative method to study the association behavior of the hydrophobically modified polyacrylamide (HMPAM) in aqueous solution was proposed based on host-guest inclusion. Scanning electron microscopy (SEM), dynamic light scattering (DLS), rheometer and fluorescence probe were also used to investigate its association behavior for comparative study. The hydrophobic association contribution rate (HACR) of HMPAM can be quantitatively calculated by means of β-cyclodextrin inclusion. The critical association concentration (CAC) of Poly (AM-co-AMPS-co-DS) (PAAD) terpolymer obtained by the HACRs was about 924 mg/L, which was almost consistent with that (882 mg/L) obtained by the method of fluorescence probe. SEM images showed that larger supra-molecular aggregates formed as HMPAM concentrations were higher than CAC. Moreover, the effects of temperature and salt on the association behavior were also characterized by the HACRs, and the results were also confirmed by the methods of rheology, DLS and fluorescence probe. Thus, HACR is another way to study the association behavior of HMPAM in aqueous solutions.