1. Phase Behavior of Charged Star Block Copolymers at Fluids Interface
- Author
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Chen, Zhan, Ribbe, Alexander E, Steinmetz, Christian, Coughlin, E Bryan, Hu, Mingqiu, Gan, Xuchen, and Russell, Thomas P
- Subjects
Macromolecular and Materials Chemistry ,Chemical Sciences ,Nanotechnology ,Bioengineering ,Architecture ,Block Copolymer ,Interfaces ,Morphology ,Phase Behavior ,Organic Chemistry ,Chemical sciences - Abstract
The phase behavior of block copolymers (BCPs) at the water-oil interface is influenced by the segmental interaction parameter ( χ${\chi }$ ) and chain architecture. We synthesized a series of star block copolymers (s-BCPs) having polystyrene (PS) as core and poly(2-vinylpyridine) (P2VP) as corona. The interaction parameters of block-block ( χ${\chi }$ PS-P2VP ) and block-solvent ( χ${\chi }$ P2VP-solvent ) were varied by adjusting the pH of the aqueous solution. Lowering pH increased the fraction of quaternized-P2VP (Q-P2VP) with enhanced hydrophilicity. By transferring the equilibrated interfacial assemblies, morphologies ranging from bicontinuous films at pH of 7 and 3.1 to nanoporous and nanotubular structure at pH of 0.65 were observed. The nanoporous films formed hexagonally packed pores in s-BCP matrix, while nanotubes comprised Q-P2VP as corona and PS as core. Control over pore size, d-spacing between pores, and nanotube diameters was achieved by varying polymer concentration, molecular weight, volume fraction and arm number of s-BCPs. Large-scale nanoporous films were obtained by freeze-drying emulsions. Remarkably, the morphologies of linear BCPs were inverted, forming hexagonal-packed rigid spherical micelles with Q-P2VP as core and PS as corona in multilayer. This work provides insights of phase behaviors of BCP at fluids interface and offer a facile approach to prepare nanoporous film with well-controlled pore structure.
- Published
- 2024