Charge and size matters—How to formulate organomodified silicones for textile applications

Abstract

Organomodified silicones (OMS), which conventionally find use in textile finishing processes, have recently become a very interesting prospect in the field of fabric softeners. Here, we present OMS-based fabric softener formulations in the form of classical emulsion (droplet size ≈0.1 μm – 10 μm) and microemulsions (droplet size ≈5 nm–50 nm) using nonionic surfactants (NIS) as emulsifier. Streaming potential measurements are used to obtain a measure of droplet surface charge, and it was found to be related to the ratio of masses of OMS and NIS present in the formulations. In this work, it is investigated how the performance of these formulations is influenced by properties such as droplet size and streaming potential. Panel tests were carried out to evaluate the sensory properties of fabric treated by these formulations, and they reveal that the classical emulsion performs better than the microemulsions. For the microemulsions, it is found that softening performance increases with streaming potential. The observed trends in softening performance are explained by considering the difference in location or penetration of softening actives on or into fabric. Two different experimental approaches are implemented to gain insights into the underlying phenomena. In the first approach, batch deposition experiments are carried out to characterize OMS deposition on fabric. In the second approach, a chromatographic technique is used to compare the deposition kinetics of different formulations. The findings of the experiments provide insights into the reasons underlying the contrasting softening performance. The final results are discussed with respect to existing literature.