Han Lijuan

Interaction of Hydrophobically Associating Polyacrylamide with Gemini Surfactant

A fatty acid disulfonate anionic gemini surfactant was prepared and the structure of the surfactant was characterized by 1 H-NMR.Hydrophobically associating polyacrylamide was prepared according to a procedure from literature.The interaction between the hydrophobically associating polyacrylamide (HAPAM) and the anionic gemini surfactant was studied by surface/interfacial tension,apparent viscosity,and atomic force microscopy (AFM).Experimental results show that HAPAM can form a network structure in the aqueous solution by self assembly.Mixed micelles are formed by the interaction of gemini surfactant micelles and the hydrophobic microdomain of the hydrophobically associating polyacrylamide in aqueous solution,which plays a remarkable role in the surfactant and polymer assembly.Mixed micelles can enhance the inter-or intra-molecular association between the polymer molecules and the surfactant,which increases the strength of the network formed by the hydrophobically associating polyacrylamide.The apparent viscosity of the solution increased by the addition of the gemini surfactant.When the addition of the gemini surfactant exceeded a certain amount,the association between the hydrophobic groups of the polymer decreased and the network formed by hydrophobically associating interaction was weakened by the surfactant micelles,which led to a decrease in solution viscosity.The polymer also largely influenced the interfacial properties of the gemini surfactant,especially the dynamical interfacial tension.A high polymer concentration led to an increase in the time required to reach equilibrium.

Self-Assembly Behavior of Hydrophobically Associating Polyacrylamide in Salt Solution

The self-assembly behavior of hydrophobically associating polyacrylamide(HAPAM)in salt solution was studied by static light scattering,dynamic light scattering,and atomic force microscopy(AFM). The apparent weight average molecular weight(Mw,a ),root mean square radius of gyration(Rg), hydrodynamic radius(Rh),and the second virial coefficient(A2),were investigated.The ratio ofRg toR h was used to determine the molecular shape of the polymer in salt solution.As the salt concentration increased,the polymer chain transformed from stretch to curl.