Multiscale Structure of Starches Grafted with Hydrophobic Groups: A New Analytical Strategy.

Starch, an abundant and low-cost plant-based glucopolymer, has great potential to replace carbon-based polymers in various materials. In order to optimize its functional properties for bioplastics applications chemical groups need to be introduced on the free hydroxyl groups in a controlled manner, so an understanding of the resulting structure-properties relationships is therefore essential. The purpose of this work was to study the multiscale structure of highly-acetylated (degree of substitution, 0.

Binary and ternary phase behaviors of short double-chain quaternary ammonium amphiphiles: surface tension, polarized optical microscopy, and SAXS investigations.

A series of short chain dialkyldimethylammonium amphiphiles ([DiC(n)][X] and [DiC(n)]2[X] with n = 6, 8, or 10) has been investigated as a function of the nature of the counteranion [X] (Cl(-) and Br(-) as classical references and MoO4(2-) and WO4(2-) as catalytic anions). Critical aggregation concentrations (CACs) in water were determined by surface tension measurements, and the binary phase diagrams of the surfactant/water systems were established using polarized optical microscopy (POM) and small angle X-ray scattering (SAXS). The evolution of microstructures and lyotropic phases were discussed in terms of surfactant chain length and counterion effect.

Counter anion effect on the self-aggregation of dimethyl-di-N-octylammonium cation: a dual behavior between hydrotropes and surfactants.

Self-aggregation of eight dimethyl-di-N-octylammonium salts ([DiC(8)]) has been investigated as a function of the nature of the counteranion. Tensiometry, conductimetry, and [DiC(8)]-selective electrode measurements highlighted three different behaviors and led to a rationalization of the aggregation process depending on the counteranion: "hydrophilic" anions (MoO(4)(2-), WO(4)(2-), SO(4)(2-), F(-)) give only unimers and micelles, whereas less hydrated anions form unimers, dimers, and either one micelle-like structure (NO(3)(-), Br(-)) or two micelle-like structures (CH(3)SO(3)(-), Cl(-)). Small-angle neutron and dynamic light scattering confirms the unusual behavior of [DiC(8)][Cl], which forms two types of aggregates: (i) disk or vesicles between 10 and 30 mM and (ii) ellipsoidal micelles above 30 mM.