Counterion‐Mediated Self‐Assembly of Ion‐Containing Block Copolymers on the Basis of the Hofmeister Series

Abstract

A Cl− and I− ion‐containing amphiphilic diblock copolymer [PEO‐b‐P(qVBC‐co‐St)], IBCP, which comprises the poly(ethylene oxide) block and poly(quaternized 4‐vinylbenzyl chloride‐co‐styrene) is prepared by sequence reactions. Then the counterion‐mediated self‐assembly behavior in aqueous solution is investigated in detail. The hydrophilicity of anion containing units (qVBC) is controlled by the nature of the different counterions after ion exchange, which is crucial in regulating the self‐assembly process. The addition of Br−, I−, and SCN− counterions (based on the Hofmeister series) results in the formation of tighter ion‐pairs with cations (i.e., more hydrophobic as the qVBC units), which triggers spheres to vesicles, micro‐meter long cylinders and “branched wormlike” aggregates, respectively. Moreover, addition of different amounts of Cl− also causes morphological transition from spheres to long cylinders. And this morphological transition is totally reversible after removing additional Cl−. The adhesive collisions of spherical particles may contribute to the observed sphere‐to‐cylinder morphological transition.

Lateral growth of cylinders

“…17 . The morphology of the cylinders was similar to the previously reported cylinders that obtained via counterion-mediated particle fusion of spherical micelles self-assembled from ion-containing block copolymers 45 . In addition, the diffraction spots in SAED pattern in Fig.…”

Reactive Oxygen Species Synergistic pH/H2O2-Responsive Poly(l-lactic acid)-block-poly(sodium 4-styrenesulfonate)/Citrate-Fe(III)@ZIF-8 Hybrid Nanocomposites for Controlled Drug Release

“…The average size of vesicles determined from TEM observation is about 180 nm, which is slightly smaller than that calculated from DLS (238 nm, Figure d). This is possibly due to the shrunk corona of the dried vesicles, which is widely report elsewhere. , After incorporation with Cit-Fe­(III), the BCP/Cit-Fe­(III) forms solid aggregates (Figure b), and the size of particle measured from TEM observation is about 210 nm, which is very similar to the result determined from DLS (Figure d). Finally, using the assemblies of BCP/Cit-Fe­(III) as templates, ZIF-8 crystals are successfully grown from BCP/Cit-Fe­(III).…”

Spatially Restricted Templated Growth of Poly(ε-caprolactone) from Carbon Nanotubes by Crystallization-Driven Self-Assembly

“…Fabrication of novel and complex hybrid hierarchical assemblies with well-defined structures is of great importance in research because of their diverse applications in nanomedicine and microelectronics. , However, robust approaches to create hybrid structures with precise shape and uniform size still remain challenging because of the immature technology in manipulating and incorporating the organic building blocks on the different inorganic substances. − Self-assembly of block copolymers (BCPs) in selective solvents offers a promising way to build different nanostructures including spheres, − cylinders, , lamellae, and vesicles . More recently, crystallization-driven self-assembly (CDSA) of BCPs with semicrystalline cores leads to the preparation of diverse anisotropic structures with controlled dimensions and size, enabling access to more complex hierarchical nanomaterials. − …”