Experimental and theoretical investigation of the interfacial phenomenon associated with wetting of trisiloxane surfactant solutions
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Date
2010Author
Radulovic, Jovana
Metadata
Abstract
Surface active agents have been successfully employed in numerous industrial,
agricultural and biomedical applications for decades. Trisiloxane surfactants in
particular have proved to be exceptionally effective as wetting enhancers; hence the
name ‘superspreaders’. Since the early ‘90s these extraordinary surfactants have
become an irreplaceable component in various products and processes. However, the
true nature of their specific wetting behaviour has not been fully revealed and their
underlying wetting mechanisms are still poorly understood despite substantial
scientific interest during the last decades. In this thesis is an attempt to shed light on
specific wetting and spreading behaviour of trisiloxane solutions.
Commercial superspreader products were tested in various environments in order to
get further insight into their performance in specific practical applications.
Experimental investigation of wetting of superspreader solutions on surfaces of
different hydrophobicity and comparison to that of a conventional surfactant revealed
superiority of trisiloxanes. Exceptional interfacial activity was explained in terms of
the specific chemical structure and ‘T’-shape of the molecule. However, sensitivity
of the trisiloxane head to low pH and long-time ageing in aqueous environment was
revealed. Performance of binary mixtures of commercial superspreaders and
conventional surfactant was also assessed. Behaviour of trisiloxanes in the capillary
action was studied. Finally, a comprehensive mathematical model for trisiloxane
wetting, which incorporates diffusion as the governing factor of the wetting process,
was developed.