Supramolecular Assemblies from Poly(styrene)-block-poly(4-vinylpyridine) Diblock Copolymers Mixed with 6-Hydroxy-2-naphthoic Acid

Supramolecular assemblies involving interaction of a small organic molecule, 2-hydroxy-6-Naphthoic acid (HNA), with poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are utilized to obtain micellar structures in solution, nanostructured thin films on flat substrates and, finally, nanoporous thin films. The formation of hydrogen bonds between HNA and the poly(4-vinylpyridine) (P4VP) blocks is confirmed by spectroscopic measurements. The accordingly P4VP/HNA hydrogen-bonded complexes are poorly soluble in 1,4-dioxane, resulting in the formation of micellar structures with a P4VP/HNA core and a polystyrene (PS) corona. Those micelles have been spin-coated onto silicon wafers, resulting in nanostructured thin films consisting of P4VP/HNA dot-like features embedded in a PS matrix. The morphology of those films has been tuned by solvent annealing. Selective dissolution of HNA by methanol results in the formation of a nanoporous thin film. The P4VP/HNA nanodomains have been also cross-linked by borax, and the thin films have been further dissolved in a good solvent for PS, leading to micelles with a structure reminiscent of the thin films

The effects of salts and ionic surfactants on the micellar structure of tri-block copolymer PEO-PPO-PEO in aqueous solution

The micelles of two poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, P123 and F127 (same mol wt of PPO but different % PEO) in aqueous solution in the absence and presence of salts as well as ionic surfactants were mainly examined by dynamic light scattering (DLS). The study is further supported by cloud point and viscosity measurements. The change in cloud point (CP), as well as the size of micelles in aqueous solution in presence of salts obeys the Hofmeister lyotropic series. Addition of both cationic cetylpyridinium chloride (CPC) and anionic sodium dodecylsulfate (SDS) surfactants in the aqueous solution of P123 show initial decrease of micellar size from 20 nm to nearly 7 nm and then increasing with a double relaxation mode, further in the presence of NaCl this double relaxation mode vanishes. The effect of surfactant on F127, which has much bigger hydrophilic part is different than P123 and have no double relaxation. The relaxation time distributions is obtained using the Laplace inversion routine REPES. Two relaxation modes for P123 are explained on the bases of Pluronic rich mixed micelles containing ionic surfactants and the other smaller, predominantly surfactant rich micelles domains

Aggregation of 1-alkyl-3-methylimidazolium octylsulphate ionic liquids and their interaction with Triton X-100 micelles

Halogen-free surface active and biamphiphilic ionic liquids 1-alkyl-3-methylimidazolium octylsulphates (Cnmim C8SO4, n = 4, 6, 8, 10) were synthesized and their aqueous solution behaviour was studied using NMR and scattering techniques.</p