Low-surface energy surfactants with branched hydrocarbon architectures

International audienceSurface tensiometry and small-angle neutron scattering have been used to characterize a new class of low-surface energy surfactants (LSESs), "hedgehog" surfactants. These surfactants are based on highly branched hydrocarbon (HC) chains as replacements for environmentally hazardous fluorocarbon surfactants and polymers. Tensiometric analyses indicate that a subtle structural modification in the tails and headgroup results in significant effects on limiting surface tensions γcmc at the critical micelle concentration: a higher level of branching and an increased counterion size promote an effective reduction of surface tension to low values for HC surfactants (γcmc 24 mN m-1). These LSESs present a new class of potentially very important materials, which form lamellar aggregates in aqueous solutions independent of dilution

Cation-cation clusters in ionic liquids: Cooperative hydrogen bonding overcomes like-charge repulsion

Direct spectroscopic evidence for H-bonding between like-charged ions is reported for the ionic liquid, 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate. New infrared bands in the OH frequency range appear at low temperatures indicating the formation of H-bonded cation-cation clusters similar to those known for water and alcohols. Supported by DFT calculations, these vibrational bands can be assigned to attractive interaction between the hydroxyl groups of the cations. The repulsive Coulomb interaction is overcome by cooperative hydrogen bonding between ions of like charge. The transition energy from purely cation-anion interacting configurations to those including cation-cation H-bonds is determined to be 3–4 kJmol(−1). The experimental findings and DFT calculations strongly support the concept of anti-electrostatic hydrogen bonds (AEHBs) as recently suggested by Weinhold and Klein. The like-charge configurations are kinetically stabilized with decreasing temperatures

Surfactants from Itaconic Acid: Physicochemical Properties and Assessment of the Synthetic Strategies

Surfactants are a wide class of compounds used in a broad spectrum of industrial and everyday applications. In this paper, we present the synthesis of a new family of surfactants having C12 and C18 alkyl chains obtained from itaconic acid and fatty amines, molecules industrially obtained from renewable resources. Main physicochemical properties of synthesized surfactants have been measured and their rheological behaviors have been evaluated at the air-water interface using the pendant drop technique. Some of the synthesized surfactants are stimuli responsive compounds, switchable to a polar form in the presence of CO2. The synthetic strategies have been optimized aiming at the sustainability of the process employing a complete set of green metrics and the software EATOS