7328-22-5Relevant articles and documents
Unique associative properties of copolymers of sodium acrylate and oligo(ethylene oxide) alkyl ether methacrylates in water
Tomatsu, Itsuro,Hashidzume, Akihito,Yusa, Shin-Ichi,Morishima, Yotaro
, p. 7837 - 7844 (2008/02/01)
A series of random copolymers of sodium acrylate and oligo(ethylene oxide) alkyl ether methacrylates (CnEmMA) with different lengths of ethylene oxide (EO) and alkyl groups were prepared by free-radical copolymerization at varying copolymer compositions. The lengths of the EO units (the number of EO units) (m) and the numbers of carbon atoms in the alkyl groups (n) ranged fro'm 0 to 8.7 and 1 to 6, respectively. The copolymers with n = 1 and m = 1-8.7 exhibited a marked increase in solution viscosity at polymer concentrations (Cp) higher than their overlap concentrations (C*) when the CnEmMA contents (x) in the copolymers were in a certain limited range. Namely, there was an optimum x value that yielded the highest viscosity as a consequence of the competition between inter- and intrapolymer associations; the maximum viscosities occurred around x ≈ 25, 15, 10, 7, and 3 mol % for m = 1, 2, 3, 4.2, and 8.7, respectively. The maximum viscosity decreased significantly as n was increased on going from 1 to 6, and for the copolymers with n = 6, no increase in the viscosity occurred, a trend opposite to what is expected to interpolymer hydrophobic associations. When Cp > C*, steady-shear viscosity depended on the nature of countercations; the viscosities were found to be higher in the order Li + > Na+ ? NH4+, whereas reduced viscosity in dilute regime (Cp C*) was independent of the species of the cations. Rheological properties were found to be typical of transient networks formed through very weak interpolymer associations. Thus, the large increase in solution viscosity was explained by simultaneous interactions of countercations with EO units via coordination and with the polyanion via counterion condensation.
