The relationships between rheological rules and cohesive energy of amphiphilic polymers with different hydrophobic groups

An amphiphilic polymer in water could form an aggregate due to its hydrophobic groups. The rheological properties of the three amphiphilic polymers' solutions are different because of their different hydrophobic groups. By using a rheometer and a rotatory viscometer, the rheological properties and apparent viscosities of three kinds of amphiphilic polymers have been studied. The results show that all of the polymers are Newtonian fluids at a low shearing rate and pseudoplastic fluids at a high shearing rate. In addition, the amphiphilic polymer-P(AM/BHAM/NaA) has the best thickening behavior and the lowest value of critical aggregation concentration (CAC), which was also verified by fluorescence spectroscopy. By combining creep-recovery with cohesive energy calculation, the structural performance and interaction energy of the aggregate is the reason for the above mentioned phenomenon. By increasing the strength of hydrophobic groups, i.e., with an oil-water partition coefficient, then the structural viscoelasticity of the groups could be improved, and the associate is easily formed in the solution.