The evolution of ABC star polymers: from trial-and-error to rational design

Abstract

ABC star polymers, consisting of three chemically distinct polymeric chains bound to a common point, have emerged over the last 35 years as versatile materials with tunable morphologies and potential applications in nanofabrication, drug delivery, or solid-state electrolytes. Despite decades of progress, well-defined synthesis and design remain a challenge due to their high synthetic complexity. This review surveys key developments in synthetic strategies, ranging from early anionic routes to modern reversible-deactivation radical polymerizations and click-driven methods, highlighting the trade-offs between architectural precision, functional compatibility, and scalability. Particular emphasis is placed on the resulting morphologies in bulk, thin-film, and solution states, where the star topology enables unique structural motifs not accessible to linear triblocks. These include complex tilings, hierarchical phases, and multicompartment micelles. Emerging computational and data-driven approaches are discussed in the context of inverse design, offering new directions for bridging idealized model systems with scalable, application-ready materials.

Fig. 1. (a) Core and (b) arm-first techniques for preparation of ABC star polymers.

Fig. 2. The synthetic pathways of the first two reported ABC stars. (a) DPE-based synthesis by Fujimoto et al., (b) chlorosilane-based synthesis by Iatrou et al. Adapted from ref. and .

Fig. 3. Representative monomers employed in anionic ABC star synthesis.

Fig. 4. Synthetic pathway for a PS–PEO–PCL star, combining anionic and ring opening polymerization. Adapted from Lambert et al.

Fig. 5. Common monomers incorporated into ABC stars via ROP, including biodegradable polyesters, hydrophilic epoxides, and functional polypeptide precursors.

Fig. 6. Schematic representation of the first-reported fully core-first syntheses, He et al. (left), Tunca et al. (right). The different polymerization mechanisms are color coded as follows: blue = ROP, green = NMP/FRP, red = ATRP.

Fig. 7. Modular approach to the synthesis of PS–PCL–PEO ABC star by Iskin et al. via three orthogonal “click” reactions. Adapted from ref. with permission.

Fig. 8. Monomers commonly used in the synthesis of responsive ABC stars.

Fig. 9. Schematic representation of the penta-responsive ABC star by Zhao et al.

Fig. 10. Contrast between approaches by Jie et al. (a) and by Shingu et al. (b) for obtaining tricyclic ABC stars. Reproduced from Shingu et al.

Fig. 11. Ternary phase diagram of the ISP star. Reproduced with permission from ref. .

Fig. 12. Ternary phase diagram of an EOF star system. Reprinted with permission from ref. .

Fig. 13. Representative micelles formed by an ABC star containing a perfluorinated segment, illustrating composition-dependent self-assembly into patchy spheres, segmented worms, vesicles, stomatocytes, and raspberry-like structures. Adapted with permission from ref. .

Fig. 14. Schematic depiction of a thermally-induced corona collapse in a PS-PNIPAM-PCL ABC star. Adapted with permission from ref. .

Fig. 15. Mechanism for a formation of “superstructure” in PB–PtBMA–P2VP ABC star, triggered by complexation of P2VP with methyl iodide. Adapted from ref. .

Matus Kalina

Babak Nouri

Kristoffer Almdal