The effect of pH on the complex formation between poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) has been studied in aqueous solutions by turbidimetric and fluorescent methods. It was shown that the formation of insoluble interpolymer complexes is observed below a certain critical pH of complexation (pH(crit1)). The formation of hydrophilic interpolymer associates is possible above pH(crit1) and below a certain pH(crit2). The effects of polymer concentrations in solution and PEO molecular weight as well as inorganic salt addition on these critical pH values were studied. The polymeric films based on blends of PAA and PEO were prepared by casting from aqueous solutions with different pHs. These films were characterized by light transmittance measurements and differential scanning calorimetry. The existence of the pH value above which the polymers form an immiscible blend was demonstrated. The transitions between the interpolymer complex, miscible blend, and immiscible blend caused by pH changes are discussed. The recommendations for preparation of homogeneous miscible films based on compositions of poly(carboxylic acids) and various nonionic water-soluble polymers are presented.

The effect of inorganic salts addition on the complex formation of poly(acrylic acid) with various non‐ionic polymers such as poly(vinyl pyrrolidone), poly(acrylamide), poly(ethylene oxide), pol(vinyl methyl ether), poly(vinyl alcohol), poly(N‐isopropylacrylamide), poly(2‐hydroxyethyl vinyl ether), hydroxypropylcellulose and hydroxyethylcellulose has been studied in aqueous solutions. It was found that, depending on the nature of the polymers and pH medium, addition of inorganic salts could increase or decrease the critical pH values of complexation. A new classification of interpolymer complexes based on critical pH values and ionic strength effects is suggested. Copyright © 2004 Society of Chemical Industry

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Literature data as well as our own experimental results devoted to the complexation of polycarboxylic acids with various water‐soluble polysaccharides (methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, starch, and dextran) by means of hydrogen bonding are systematized and analyzed. The specific peculiarities of interpolymer complexes based on polysaccharides‐polycarboxylic acids are demonstrated. The perspectives for the application of these interpolymer complexes are considered. It was shown that these materials possess good biocompatibility and adhesive properties. The promising directions for further study of interpolymer complexes between polycarboxylic acids and nonionic polysaccharides as well as existing gaps in the knowledge in this field are pointed out.Formation of compact IPCs and hydrophilic interpolymer associates.magnified imageFormation of compact IPCs and hydrophilic interpolymer associates.

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.