Monitoring Micelle Formation of Nonionic Polyurethane in Water by Fluorescence Spectrophotometry

Abstract

A series of nonionic polyurethanes were dissolved in water and their miceller selfassembly behaviors were characterized by aid of a fluorescence spectrophotometer. Fluorescence and resonance light scattering techniques were carried out for characterizing the micelles, and information such as aggregation number, critical micelle concentration, micropolarity, and micelle volume change was obtained. The micropolarity decreased as the aggregation number increased. The nonionic polyurethane micelle volume with two long ethoxyl chains per polyurethane molecule was smaller than the one with short chains, even with the same aggregation number, and was less polar. The micropolarity depended on both the aggregation number and the volume of a single micelle.

Sticker Multivalency in Metallo-supramolecular Polymer Networks

“…The approximation of the corresponding aggregate concentrations yields similar weight portions between 6 and 11 wt % for both PUs. In general, the self-assembly of amphiphilic (nonionic) PUs into micellar structures is most-pronounced and thus commonly studied in aqueous environments 28,29 but also known in polar organic solvents. 30 In a former study, we correspondingly observed the complete aggregation of similar pEG-based PUs with terpyridine side groups in water while a mixture of aggregates and molecularly dissolved chains occurred in MeOH.…”