Structure formation in solutions of isotactic poly(methacrylic acid) in dimethyl formamide

Structure formation in solutions of non-neutralised isotactic poly(methacrylic acid) in dimethyl formamide was studied. Fourier transformed infrared spectroscopic measurements, X-ray diffraction analysis and dynamic rheological observations revealed that two different processes of structure formation can take place. The first process can lead to the formation of very weak, thermoreversible gels. It is proposed to consist of an intramolecular coil-to-helix transition, followed by an intermolecular association. The second one shows the characteristics of a crystallisation into a supramolecular organisation different from what is obtained in the first process. These processes can compete with each other and this depends on the experimental conditions, the molar mass and the tacticity of the sample.