Complex formation between poly(acrylic acid) and methylcellulose in aqueous solutions has been studied by viscometric and turbidimetric methods. The critical pH values in their dependence of polymer concentration were determined. The in¯uence of the nature of a nonionic polymer on the composition and stability of interpolymer complexes is shown. The phase behaviour of acrylic acidgraft-methylcellulose copolymer in aqueous solutions is analysed from their complexation point of view.

The phase behavior of methylcellulose‐poly(acrylic acid) mixtures was studied in aqueous solution. It was shown that the complexation between the two polymers decreases considerably the cloud‐point of methylcellulose. The addition of inorganic salts shifts the critical pH values toward a higher pH region. Films were prepared based on methylcellulose‐poly(acrylic acid) blends and were analyzed by dynamic mechanical thermal analysis, scanning electron microscopy and thermal gravimetric analysis. The miscibility between the two polymers in the films was shown. It was found that the thermal treatment of the films leads to their cross‐linking with the formation of materials swellable both in water and ethanol. © 2003 Society of Chemical Industry

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The interactions between hydroxypropylmethylcellulose (HPMC) and poly(acrylic acid) (PAA) as well as poly(methacrylic acid) (PMAA) resulting in formation of hydrophobic interpolymer complexes (IPC) via hydrogen bonding have been studied in aqueous solutions in acidic medium. The formation of IPC of two different compositions (2:1 and 4:1) has been detected for complexes of PAA and HPMC. The critical pH values for complexation of HPMC with PAA and PMAA were determined by the turbidimetric method. It was found that PAA shows the lower complexation ability compared to PMAA due to the more hydrophobic nature of the latter polyacid. The temperature-induced phase separation in HPMC-PAA solution mixtures depends greatly on the components ratio and PAA molecular weight. The complexation ability of hydroxypropylmethylcellulose with respect to poly(acrylic acid) was found to be similar to the complexation ability of methylcellulose, lower than that of hydroxypropylcellulose and higher than that of hydroxyethylcellulose.

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