Melting and aggregation behaviour of novel bio-compatible anionic, cationic and catanionic surfactant systems

摘要

The demands on surfactants systems have increased over the last decades. On the one hand, their performance should be perfectly adapted to the respective tasks. Yet, this comprises the least possible effort concerning complexity and affordable costs for the particular requirement. On the other hand, legal requirements enforce the utilization of compounds with the least possible toxic and environmental impact.Therefore, two main ideas were followed within the scope of this thesis. First, the implementation of Ionic Liquid-like properties in amphiphilic compounds was tested by exploiting the knowledge on ion affinities, acidities and alkylchain flexibilities. For that purpose, carboxylate ions of varying chainlength, with and without ether functionalities, were combined with a diversity of ammonium bases, yielding anionic, cationic or even catanionic surfactant systems. Bases were chosen with regard to their low toxicity (choline), to their accustomed utilisation in common processes (triethanolamine, long-chain primary amines) or to their improvable performance in concrete applications (Lidocaine). The synthesised compounds were characterised with respect to their potential Ionic Liquid - and surfactant-features. Concretely, melting, thermal stability and partially conductivity were evaluated. Likewise, the aggregation and the solution behaviour in diluted and concentrated mixtures with water were deduced. The second main idea was the design of low toxic catanionic surfactant systems. This aim was tried to be accomplished in two steps: •First, low toxic cationic surfactants with natural osmolyte headgroups, such as choline and ectoine, were synthesised and characterized according to their physico-chemical, cytotoxic and biodegradation features.•Second, these surfactants were combined with long-chain- and alkylether carboxylates with known/or approved biocompatibility. Adjacently, the resulting mixtures were investigated with respect to their aggregation behaviour in dilute aqueous solution and their potential to form vesicles – one of the most used carrier systems for pharmaceutically active agents. Further, their efficiency to stabilise emulsions according to the Pickering mechanism was elucidated.