Abstract
The wettability of solids is important from both practical and theoretical viewpoints. In this study, we measured the contact angle of aqueous solutions of polysorbates (Tween 20, Tween 60, and Tween 80) on polytetrafluoroethylene (PTFE), polyethylene (PE), polymethyl methacrylate (PMMA), polyamide (nylon 6), and quartz. Based on the obtained results, the adsorption of Tween 20 (T20), Tween 60 (T60), and Tween 80 (T80) at the solid-water interface was determined based on the structure and size of their molecules. Next, the tendency of polysorbates to adsorb at the solid-water interface was considered based on the Gibbs standard free energy of adsorption (ΔGadso). This energy was evaluated using various methods, including a method we propose based on the critical micelle concentration (CMC) and the contact angle of water and solution at the CMC, as well as their surface tension. The ΔGadso values obtained by this method were comparable to those calculated from the Langmuir equation. Taking into account the Tweens tendency to adsorb at the solid-water interface, the measured contact angle, the components and parameters of surface tension of Tweens solutions and solids, and the surface tension of water and its Lifshitz-van der Waals component that we determined, the wetting process in the solid-solution drop-air system was analyzed. The results based on the mentioned parameters showed that it is possible to predict the wettability of apolar, monopolar, and bipolar solids using the aqueous Tweens solution and their solution adhesion.
Highlights
Polysorbates are extensively used in food, cosmetic, pharmaceutical preparations, bioresearch, and chemical compounds detection owing to their nontoxicity, easy accessibility, emulsification, and solubilisation [1,2,3,4]
If the liquid is not spread completely over the solid surface, solid wetting can be described by the modified Young equation [27]: γS − π1 − = γL cos θ where γS is the solid surface tension, γL is the liquid or solution surface tension, γSL is the solid-liquid interface tension, π1 is the film pressure behind the liquid or solution drop settled on the solid surface, π2 is the film pressure under the liquid or solution drop settled on the solid surface, and θ is the contact angle
From the data reported in the literature on the adsorption of Tween 20 (T20), Tween 60 (T60), and Tween 80 (T80) at the water-air interface, and the analysis of the isotherms of the contact angle of the aqueous solution of these surfactants on the PTFE and PE, our results showed that the adsorption of Tweens at the water-air interface is comparable to that at the PTFE-water and PE-water interfaces
Summary
Polysorbates are extensively used in food, cosmetic, pharmaceutical preparations, bioresearch, and chemical compounds detection owing to their nontoxicity, easy accessibility, emulsification, and solubilisation [1,2,3,4]. Polysorbates such as Tween 20 and Tween 60 were found to be capable of enhancing drug transport across biological membranes [5]. The solid-water interface tension changes that are due to surfactants adsorption depend on the length of hydrophobic chain of surfactant molecules and on their orientation toward the water phase. The orientation toward the water phase by the hydrophobic part of molecules causes the increase of the solid-water interface tension but the reverse orientation can result in its decrease [20]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
