Attempts to prepare vanous peripheral tetra-and octasubstituted (phtha1ocyaninato)iron derivatives R,PcFe [n = 4:

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A series of hydrophobically modified poly(acrylic acid)(R H -PAA) were synthesized by solution copolymerization of acrylic acid with a small amount of alkyl acrylate (alkyl chain with a length of 8,12,14,16,18) and their solution properties were also systematically studied. It was found that the random distribution of alkyl acrylate along the polymeric backbone imparts these new materials pronounced associating ability in aqueous solution and the associating abilities vary with the chain length of the hydrophobic groups. In dilute solution, intramolecular association is observed from the intrinsic viscosity and the dependence of the intrinsic viscosity on chain length and ionic strength is also discussed. In semiconcentration solution, the modified polymers exhibit viscosities of several orders of magnitude higher than the unmodified poly(sodium acrylate) due to the strong intermolecular hydrophobic association. And the viscosifying effects become more significant with the increasing length of the alkyl chain. The copolymer solutions are highly pseudoplastic. Evidences for the hydrophobically associating interaction between hydro-carbon groups are provided by the dependence of the Brookfield viscosity on concentration, temperature, shear rate, ionic strength and pH. FIGURE 2. Relationship between Brook®eld viscosity and solution concentration: effect of the modi®cation degree and comparison with¯uorocarbon groups.

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