Poly(4‐vinyl imidazole): A pH‐Responsive Trigger for Hierarchical Self‐Assembly of Multicompartment Micelles Based upon Triblock Terpolymers

Abstract

Poly(vinyl pyridine) has widely been used as a pH‐responsive polymer to trigger changes in self‐assembly of block copolymer micelles. However, the polymer is known to display toxic features, which limits its ultimate applicability for biological applications. Here, poly(4‐vinyl imidazole) (P4VIm), a much more biocompatible polymer, is used as a pH‐responsive block to modulate the self‐assembly of ABC triblock terpolymers. In this article, the synthesis of the poly(1‐acryloyl fructopyranose)‐block‐ poly(n‐butyl acrylate)‐block‐ poly(4‐vinyl imidazole) (PFruA52‐b‐PBuA300‐b‐P4VIm250) triblock terpolymers is first discussed by sequential reversible addition fragmentation chain transfer (RAFT) polymerization. Subsequently, the structure formation of the triblock terpolymer is elucidated by step‐wise solvent exchange. The polymer readily dissolves in methanol, but self‐assembles into micelles with PBuA cores and mixed shell in methanol–water mixtures. Solvent exchange against buffer solutions of pH 6–6.5 leads to collapse of P4VIm due to deprotonation and induces self‐assembly into caterpillar‐like non‐spherical nanoparticles, most likely via the formation of intermediate Janus particles. The rearrangement into larger hierarchical structure, as seen by small angle X‐ray scattering (SAXS), is found to process within several hours. The article is concluded by demonstrating lower cytotoxicity values for the present polymer in comparison to a structurally analogous triblock terpolymer based on poly(vinyl pyridine).

Morphology Control of Multicompartment Micelles in Water through Hierarchical Self-Assembly of Amphiphilic Terpolymers

“…Recently, we and others started transferring this concept to aqueous systems, ,− as shown on the hierarchical self-assembly of linear poly­(ethylene oxide)- block -polystyrene- block -poly­(2-vinylpyridine) (PEO- b -PS- b -P2VP) terpolymers. The latter two blocks collapsed sequentially into precursor micelles with a polystyrene (PS) core and mixed poly­(ethylene oxide) (PEO)/P2VP corona, which further served as subunits for the supracolloidal aggregation into linear chains .…”

Mimicking the Natural World with Nanoarchitectonics for Self‐Assembled Superstructures

“…[40] Pispas and co-workers reported worm-like core-shell nanoparticles from the co-assembled double hydrophilic block polyelectrolyte with an oppositely charged fluorosurfactant. They synthesized the polyelectrolyte- [39] with permission of the Wiley.…”

“…They further showed that such types of self‐assembled microstructures can be useful in biomedical applications. In another report, [39] they used linear triblock glycopolymer containing both a poly(4‐vinyl imidazole) (P4Vim) block and a hydrophilic fructose functionalized block and their self‐assembly led to formation of structures with caterpillar‐like structural morphologies (Figure 8b–d). The triblock terpolymers poly(1‐acryloyl fructopyranose)‐block‐ poly(n‐butyl acrylate)‐ block‐ poly(4‐vinyl imidazole) (PFruA 52 ‐b‐PBuA 300 ‐b‐P4VIm 250 ) were synthesised by reversible addition fragmentation chain transfer (RAFT) polymerization reactions.…”

Two dimensional hierarchical architectures fabricated by the self-assembly of poly(3-hexylthiophene)-b-polyethylene glycol

“…[9][10][11][12] In addition, self-assembly of polymers has also proved to be an effective and low-cost method with which to prepare hierarchical architectures. Various hierarchical nanostructures, such as complex spherical micelles, [13][14][15][16][17][18][19] super-vesicles, 20 one-dimensional nanostructures [21][22][23][24][25][26][27] and two dimensional (2D) nanostructures are obtained by the self-assembly of polymers. [28][29][30][31][32] Various polymers have been developed and used to prepare well-defined hierarchical architectures.…”