Direct measurement of interaction force between hydrophilic silica surfaces in triblock copolymer solutions with salt by atomic force microscopy

Dewetting-Assisted Interface Templating: Complex Emulsions to Multicavity Particles

Interfacial tension-driven formation of intricate microparticle geometries from complex emulsions is presented in this work. Emulsion-templating is a reliable platform for the generation of a diverse set of microparticles. Here, water-in-styrene-in-water complex emulsions undergo reproducible metamorphosis, i.e., from liquid state emulsions to solid structured microparticles are employed. In contrast to the traditional usage of glass-based microfluidics, polydimethylsiloxane (PDMS) swelling behavior is employed to generate complex emulsions with multiple inner cores. In the presence of block copolymer surfactant, these emulsions undergo gravity-driven dewetting of styrene, to transform into membranous structures with compartments. Further polymerization of styrene skeletal remains resulted in microparticles with interesting geometries and intact membranes. Mechanical and confocal microscopic studies prove the absence of polystyrene within these membranes. Using osmotic pressure, membrane rupture and release of encapsulated gold nanoparticles from such polymerized emulsions leading up to applications in cargo delivery and membrane transport are promoted. Even after membrane rupture, the structured microparticles have shown interesting light-scattering behavior for applications in structural coloring and biosensing. Thereby, proving PDMS-based swelling as a potential methodology for reproducible production of complex emulsions with a potential to be transformed into membranous emulsions or solid microparticles with intricate structures and multiple applications.

DPD Study on the Interfacial Properties of PEO/PEO-PPO-PEO/PPO Ternary Blends: Effects of Pluronic Structure and Concentration

Using the method of dissipative particle dynamics (DPD) simulations, we investigated the interfacial properties of PEO/PEO-PPO-PEO/PPO ternary blends composed of the Pluronics L64(EO₁₃PO₃₀EO₁₃), F68(EO₇₆PO₂₉EO₇₆), F88(EO₁₀₄PO₃₉EO₁₀₄), or F127(EO₁₀₆PO₇₀EO₁₀₆) triblock copolymers. Our simulations show that: (i) The interfacial tensions (γ) of the ternary blends obey the relationship γF68 < γL64 < γF88 < γF127, which indicates that triblock copolymer F68 is most effective in reducing the interfacial tension, compared to L64, F88, and F127; (ii) For the blends of PEO/L64/PPO and the F64 copolymer concentration ranging from c_cp = 0.2 to 0.4, the interface exhibits a saturation state, which results in the aggregation and micelle formation of F64 copolymers added to the blends, and a lowered efficiency of the L64 copolymers as a compatibilizer, thus, the interfacial tension decreases slightly; (iii) For the blends of PEO/F68/PPO, elevating the Pluronic copolymer concentration can promote Pluronic copolymer enrichment at the interfaces without forming the micelles, which reduces the interfacial tension significantly. The interfacial properties of the blends contained the PEO-PPO-PEO triblock copolymer compatibilizers are, thus, controlled by the triblock copolymer structure and the concentration. This work provides important insights into the use of the PEO-PPO-PEO triblock copolymer as compatibilizers in the PEO and PPO homopolymer blend systems.