Synthesis And Performance Of Hydrophobically Modified Polyacrylamide With Surface Activity

Polyacrylamide (PAM) as a representative of water-soluble polymers has been applied extensively in many fields, especially in enhanced oil recovery. Since there are some limitations in the application of PAM such as low tolerance of high salinity, high temperature and high shear rate, hydrophobically modified polyacrylamide (HMPAM) that can bear the high salinity, high temperature and high shear rate and show surface activity was synthesized by the copolymerization of acrylamide and NP₁₀AA or Span80AA in this paper.First, NP₁₀AA (Nonylphenol polyoxyethylene ether acrylate) or Span80AA was synthesized by the esterification of NP-10 (Nonylphenol polyoxyethlene ether) or Span80 and acylic acid. And the optimum reaction conditions were determined in order to enhance esterification yield. Then a series of HMPAM were synthesized by radical copolymerization in water solution. The factors to influence copolymerization yield and molecular weight were discussed. The molecular structure of copolymer was characterized by FT-IR absorption spectrum and the molecular weight was measured by the viscosity method. Finally, the properties of HMPAM aqueous solution including apparent viscosity, surface tension and interfacial tension were investigated in detail.It is found that HMPAM was better than PAM to enhance solution viscosity and there was a critical associating concentration (CAC) in HMPAM aqueous solution. When the HMPAM concentration was lower than CAC, the characteristic of HMPAM is similar to that of PAM. While higher than CAC, the apparent viscosity of the HMPAM solution would sharply rise by a wide margin and exhibited a clear tolerance of high salinity, high temperature and high shear rate. The distinguishing quality was more and more obvious as the increasing amount of NP₁₀AA in copolymer. It is more important that HMPAM displayed surface activity and reduced surface tension of the aqueous solution, which PAM did not possess. Surface tension could reduce to 42mN/m at the critical micelle concentration of HMPAM, which is a little higher than surface tension of NP-10 as 32mN/m. The interfacial tension between diesel as oil-phase and HMPAM solution as water-phase was 7.6mN/m, while the interfacial tension between diesel and PAM solution was 19.4mN/m.