Fabric softeners' main ingredients are surfactants, which are compounds that stick to clothing during the rinse cycle and make them feel softer. Scientists have been studying fabric softeners for decades, and many believe that surfactants work by forming a lubricating layer on clothing. But to date, no one knows how the softeners work on a molecular level. So, Evdokia K. Oikonomou, Jean-François Berret and colleagues set out to devise a new method to look more closely at the interaction between cotton fabric and fabric softeners as a first step toward developing more eco-friendly products.
The researchers studied how a double-tailed cationic surfactant, which is often used in commercial fabric softeners, would combine with natural cellulose nanocrystals -- a stand-in for cotton -- using multiple techniques including light scattering and optical and electron microscopy. The study showed that the concentration of surfactant affected vesicle size. The concentration of surfactant also affected how these vesicles arranged themselves, sometimes nesting within each other to form multiple layers. The researchers say their technique could speed up manufacturers' assessment of fabric softeners' efficiency and potentially help get newer, more environmentally friendly products to the market faster.