The Zetasizer Nano ZS is used to compare three laundry detergents. Size measurements show a multimodal distribution indicating the presence of micelles and additives. Their zeta potentials, though very different are all highly negative.
Three commercial laundry agents produce size distributions with a main micelle peak near 10nm, a larger peak near 200nm (probably carboxyl methyl cellulose), and two of these consumer products showed an additional peak in the micron region. This is speculated to be very large molecular weight additives to reduce redeposition of dirt back onto the clothes. The average zeta potential of the detergent with the smallest micelles was -55mV, the one with the largest micelles showed -38mV, indicating strong formulation stability in all cases.
Product performance, product ageing, consistency and robustness of the final product properties are key objectives during the development of consumer products. Product performance issues are continuously changing because they include changing consumer expectations, regulatory requirements and developing environmental concerns.