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Hydrophobically Modified Polyelectrolytes, 4. Synthesis and Solution Properties of Fluorocarbon‐Containing Poly(acrylic acid)
Author(s) -
Zhou Hui,
Song GuoQiang,
Zhang YunXiang,
Chen Junyan,
Jiang Ming,
HogenEsch Thieo E.,
Dieing Reinhold,
Ma Lian,
Haeussling Lukas
Publication year - 2001
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20011001)202:15<3057::aid-macp3057>3.0.co;2-5
Subject(s) - polyelectrolyte , polymer chemistry , chemistry , acrylic acid , fluorocarbon , hydrophobic effect , polymer , aqueous solution , pyrene , intermolecular force , hydrophobe , viscosity , intrinsic viscosity , copolymer , chemical engineering , organic chemistry , materials science , molecule , biochemistry , engineering , composite material
Hydrophobically modified (HM) poly(acrylic acid) (PAA) was prepared by radical copolymerization of acrylic acid (AA) and a small amount of 2‐( N ‐ethylperfluorooctanesulfoamido)ethyl acrylate (FA) or 2‐( N ‐ethylperfluorooctanesulfoamido)ethyl methacrylate (FMA) in benzene. In aqueous solutions, above a critical concentration, the modified polymer in contrast to PAA exhibits a sharp increase in viscosity with increasing polymer concentration. This behavior, typical of hydrophobically modified water‐soluble polymers, is due to the formation of strong intermolecular hydrophobic association of pendent fluorocarbon groups. As shown by viscosity measurement factors such as NaCl, surfactants, temperature and pH play a very important role in the formation of hydrophobic association. For instance the behavior of viscosity as a function of pH and NaCl indicates the occurrence of competition of polyelectrolyte effects and hydrophobic association. Thus, hydrophobic association is favored under conditions where the chains carry lighter charge or where the charges are screened by the presence of salts. Studies related to the dilute solution property of the HMPAA provide information of competition between electrostatic repulsion and intramolecular hydrophobic association, which is reflected by the variation of intrinsic viscosity as a function of NaCl concentration. The extremely high value of Huggins coefficient ( k H ) of modified polymers at high NaCl concentration also gives us evidence of intermolecular hydrophobic association between polymer coils. Fluorescence studies of HMPAA show that the pH effects obviously on the FC hydrophobic association, and also that the pyrene fails to detect aggregation of fluorocarbon groups at pH > 7 by combining with the results of viscosity properties, due to its poor affinity to the fluorocarbon microdomains.