Evaluation of amylopectin clusters and their interaction with nonionic surfactants.

The interaction between polyoxyethylene (7 and 23) dodecyl ether (Unitol L-70 and L-230, respectively) and polyoxyethylene (9.5) nonylphenol ether (Renex 95) with amylopectin was studied employing the relative intensities of pyrene fluorescence emission bands 1 to 3, and excimer to monomer ratios. The pyrene concentration was very low (1mumol/L), and the probe was added to amylopectin solution by two different methods. These experimental conditions have given information about how amylopectin branch structure affects the molecular diffusion in aqueous solution. Amylopectin clusters are formed from the biopolymer outer branches. The cluster polarity is similar to ethylene glycol, confirmed by the Reichardt dye measurements. Inside the clusters, amylopectin-Unitol surfactant complexes can form with cac and cmc dependent on the biopolymer concentration. The micellar aggregation number of 60+/-5 was determined through pyrene steady-state fluorescence quenching experiments.