Study of the Conformational State of Non-Cross-Linked and Cross-Linked Poly(alkylmethyldiallylammonium chlorides) in Aqueous Solution by Fluorescence Probing

The aggregation behaviour of novel non-cross-linked and cross-linked poly(alkylmethyldiallylammonium chlorides) in aqueous solutions has been investigated by fluorescence spectroscopy using pyrene as a probe. These copolymers were found to exhibit similar aggregate properties as the corresponding polysoaps with bromide counterion. The formation of hydrophobic microdomains, as evidenced by the changes in the ratio I1/I3 of the intensities of the first and third vibronic peaks in the florescence spectrum of the pyrene molecule, was revealed to be dependent on the content of n-dodecyl groups in the copolymers. No conformational transition to compact coils was found in the case of non-cross-linked and cross-linked homopolymers as indicated by the absence of binding of pyrene to hydrophobic microdomains. The critical aggregation concentration (CAC) for the polysoaps in aqueous solution was found to decrease with increasing total hydrophobicity of the side chains in the macromolecules. The presence of sodium chloride and elevated temperatures facilitate the formation of hydrophobic microdomains in compact coil conformations for these polysoaps in aqueous solution.