Wetting of PTFE and Glass Surfaces by Aqueous Solutions of Cationic and Anionic Double-Chain Surfactants

Abstract

The wetting of hydrophobic and hydrophilic solid surfaces by surfactant solutions is an important research topic recently because of its profound practical applications. The wettability of two double-chain surfactants (cationic, didodecyldimethylammonium bromide or DDAB, and anionic, aerosol OT or AOT) solutions on poly(tetrafluoroethylene) (PTFE) and glass surfaces has been investigated here. Different physicochemical parameters such as critical micelle concentration (CMC) and surface tension, contact angle, surface excess at air−water and solid-water interfaces, work of adhesion, and free energy of wetting have been estimated for two double-chain surfactants solutions and compared with the reported results of single-chain surfactants. The double-chain surfactant solutions showed maximum lowering of surface tension values (24.36 and 26.35 mN/m for DDAB and AOT, respectively) and a change in contact angle values from pure water on PTFE (∼38°for DDAB and AOT) and glass (∼26.5 and 24°for DDAB and AOT, respectively) surfaces compared to the conventionally studied single-chain surfactants. The surfactant molecules mostly formed a monolayer adsorption on both surfaces during the wetting process. The surface excess values of both of the surfactants on PTFE−water and glass−water interfaces are 0.759 and 0.850 times lower than that of the air−water interface, respectively.

Wettability alteration by novel betaines at polymer–aqueous solution interfaces

“…The variations of the contact angle values with the increasing concentration of 18C and 18S are presented in Figure 2 for PTFE and PMMA surfaces. Figure 2a clearly depicts that the dependency of contact angle with the logarithm of concentrations on the PTFE surface are different from other researchers' conclusions[12,18,19,31] : for 18C and 18S, the contact angle keep almost a constant value in a wide range of surfactant concentration even more than CMC of individual surfactant solution.Above 1×10 -4 mol/L, the contact angles of both 18C and 18S show rapid downward trend and the values of 18C are significantly lower than that of 18S. However, for the conventional surfactants, there is a decrease in contact angle with the increase in surfactant concentration until CMC of surfactant solution and above that it is almost constant.…”

Trimethyl borate‐treated polytetrafluoroethylene micropowders with improved hydrophilic and adhesive properties based on coordination bond theory

“…In Figure A, the water contact angle decreased from 115° for the unmodified PTFE to 85.4° after the modification. Additionally, the water contact angle of the treated PTFE (85.4°) is similar to the results of PTFE treated with a surfactant …”

“…A study by Biswal and Paria 2011 reported on the absorption and wetting behavior of 2 nonionic surfactants (TX‐100 and CO‐630). Furthermore, the wettability of 2 double‐chain surfactants (cationic DDAB, and anionic AOT) solutions on PTFE surface was investigated by Biswal and Paria 2012 . In the above studies, the results revealed an evident improvement in the hydrophilic property of PTFE micropowders via treatment with the surfactant.…”

Interfacial and wetting behavior of natural–synthetic mixed surfactant systems

“…Fig. 2 35 A comparison of the surface tension results between Shikakai and DDAB shows that Shikakai has a higher CMC value as well as a higher minimum surface tension at CMC than that of DDAB, which indicates that the former is less surface active. Although the nal concentration for the minimum surface tension at CVC is a little higher for DDAB than for Shikakai, the minimum surface tension is signicantly lower ($24.36 mN m À1 ).…”

“…33,34 DDAB was also chosen as a synthetic surfactant because of its superior performance to many other conventionally used synthetic single as well as double-chain surfactants. 35 Addition of a cationic surfactant can also enhance the storage life of natural surfactant solutions by preventing fungal attack, which is also an additional advantage. This study shows that the addition of a double chain cationic surfactant can dramatically enhance the performance of a plant based surfactant.…”