Wetting dynamics of polyoxyethylene alkyl ethers and trisiloxanes in respect of polyoxyethylene chains and properties of substrates

Wetting performance of aqueous solutions of trisiloxane surfactants (TEOn) and polyoxyethylene alkyl ethers (C10EOn) on polypropylene, Parafilm and Teflon AF surfaces in a wide range of concentrations has been investigated. Surfactants C10EOn only facilitate partial wetting of water on all surfaces, but TEOn surfactants induce superspreading on polypropylene and Parafilm at room temperature (22 °C) at critical wetting concentration (CWC). Influence of the length of EO chains on wetting ability has a completely different character for C10EOn and TEOn surfactants. In the case of C10EOn the final contact angle increases on all substrates used with increasing number of EO units. However, the final contact angles for droplets of TEOn solutions decrease with increasing of n(EO) reaching a minimum values at n(EO) = 6 at the critical aggregation concentration (CAC), or show complete spreading (the final contact angle is nearly zero) for n(EO) = 5–8 at 1 CWC on moderately hydrophobic substrates. Temperature-dependent spreading behaviour of both TEOn and C10EOn surfactant solutions has also been studied. It has been shown for the first time, that tuning of spreading performance with temperature for polyoxyethylene alkyl ether surfactants is possible. The increase of spreading capability for both trisiloxane surfactant solutions and polyoxyethylene alkyl ethers solutions is observed at temperature close to the cloud point for a given surfactant