The self-assembly of two nonionic surfactants, pentaethylene glycol monododecyl ether (C12E5) and n-dodecyl-ß-maltoside (ß-C12G2), in the presence of a purpose-synthesized silica sol of uniform particle size (diameter 16 nm) has been studied by adsorption measurements, dynamic light scattering and small-angle neutron scattering (SANS) using a H2O/D2O mixture matching the silica, in order to highlight the structure of the surfactant aggregates. For C12E5 strong aggregative adsorption onto the silica beads, with a high plateau value of the adsorption isotherm above the CMC was found. SANS measurements were made at a series of loadings, from zero surfactant up to maximum surface coverage. It is found that the spherical core-shell model nicely reproduces the SANS data up to and including the local maximum at q = 0.42 nm-1 but not in the Porod region of high q, indicating that the surface area of the adsorbed surfactant is underestimated by the model of a uniform adsorbed layer. A satisfactory representation of the entire scattering profiles is obtained with the model of micelle-decorated silica beads, indicating that C12E5 is adsorbed as spherical micellar aggregates. This behaviour is attributed to the high surface curvature of the silica which prevents an effective packing of the hydrophobic chains of the amphiphile in a bilayer configuration. For the maltoside surfactant ß-C12G2 very weak adsorption on the silica beads was found. The SANS profile indicates that this surfactant forms oblate ellipsoidal micelles in the silica dispersion, as in the absence of the silica beads.

The interactions, in aqueous medium, between hydrophobically end-capped poly(ethylene oxide) (PEO) and sodium dodecyl sulfate (SDS) have been investigated by means of tensiometry, 13C NMR spectroscopy and small-angle neutron scattering (SANS). Besides the association of SDS with the ethylene oxide backbone of associative polymer (AP), revealed by 13C NMR, SDS interacts with hydrophobic endcaps leading to the formation of mixed aggregates. At low SDS concentration, the formation of flowerlike mixed aggregates is governed by AP. Despite the poor affinity between hydrocarbon and fluorocarbon chains, uncooperative binding was detected between SDS and fluorinated AP end groups. With a further increase of SDS concentration, the critical aggregation concentration (cac) marks the onset of SDS cooperative binding with AP end-caps. This process driven by SDS leads to the formation of micellar aggregates with a necklacelike structure. Due to the SDS/AP complex formation, the surfactant aggregation number determined by SANS is lower than that observed in pure water.

Noncovalent interactions play key roles in many natural processes leading to the self-assembly of molecules with the formation of supramolecular structures. One of the most important forces responsible for self-assembly is hydrogen bonding, which also plays an important role in the self-assembly of synthetic polymers in aqueous solutions. Proton-accepting polymers can associate with proton-donating polymers via hydrogen bonding in aqueous solutions and form polymer-polymer or interpolymer complexes. There has been an increased interest among researchers in hydrogen-bonded interpolymer complexes since the first pioneering papers were published in the early 1960s. Several hundred research papers have been published on various aspects of complex formation reactions in solutions and interfaces, properties of interpolymer complexes and their potential applications. This book focuses on the latest developments in the area of interpolymer complexation via hydrogen bonding. It represents a collection of original and review articles written by recognized experts from Germany, Greece, Kazakhstan, Poland, Romania, Russia, UK, Ukraine, and the USA. It highlights many important applications of interpolymer complexes, including the stabilization of colloidal systems, pharmaceuticals, and nanomaterials.

Small-angle Scattering from Self-Assembled and Hierarchical Structures