Time-resolved analysis of surfactant-surface interaction
Gabriel Ohlsson Sep 10, ’19 ~ 3 min

Time-resolved analysis of surfactant-surface interaction

Surfactants are key components in many products and processes where their surface-active properties are needed, and in such applications, the surfactant-surface interaction dynamic could be critical. Here we show how the surfactant interaction with surfaces can be analyzed in a time-resolved manner at the nanoscale.

Monitoring and quantification of surfactant adsorption to a surface

In several products and processes, such as in detergents and cleaning agents, in pharmaceutical formulations, in oil recovery, CMP, as well as in mining, the surfactant-surface interaction dynamic is critical to the application. It is therefore relevant to understand these processes at the nanoscale. In this study, QSense QCM-D, which is a surface-sensitive real-time technology, was used to characterize the surfactant adsorption. Two different surfactants were analyzed, Triton-X and ßOG. The focus of the QCM-D measurements was to analyze:

  • the surfactant adsorption dynamics
  • the amount of surfactant adsorbed, and
  • the stability of the surfactant-surface interaction
Experimental Surfactant adsorption

The surface interaction dynamics differ between the two surfactants

The results, Figure 1, show that both Triton X-100 and ßOG adsorb to the surface. However, the time to saturation differs between the two, and Triton X-100 reaches saturation faster that ßOG even though the concentration was lower. The results also show that ßOG forms a thicker layer than the Triton X-100 and that more ßOG than Triton X-100 remains at the surface after rinse.

Surfactant adsorption Triton X-100 vs BOG

Figure 1. Time-resolved thickness change as the surfactants, Triton X-100 and ßOG, adsorb to the sensor surface. 

Key takeaways from the time-resolved surface interaction analysis:

  • Triton X-100 reaches saturation faster than βOG
  • βOG forms a soft film
  • Triton X-100 forms a rigid film
  • βOG forms a thicker layer than Triton X-100

Concluding remarks

In several products and processes, the surfactant-surface interaction dynamic is important and therefore relevant to understand at the nanoscale. QCM-D analysis provides information on surfactant-surface interaction processes under a variety of different substrate- and experimental conditions. Via this quantification of the surfactant-surface interaction, conclusions can be drawn regarding the suitability of surfactants in different applications.

Download the case study to read more

Case Study  Analysis of surfactant - surface interactions with QSense  Download


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