Giant Molecular Shape Amphiphiles Based on Polystyrene–Hydrophilic [60]Fullerene Conjugates: Click Synthesis, Solution Self-Assembly, and Phase Behavior

Abstract

This paper reports a comprehensive study on the synthesis and self-assembly of two model series of molecular shape amphiphiles, namely, hydrophilic [60]fullerene (AC(60)) tethered with one or two polystyrene (PS) chain(s) at one junction point (PS(n)-AC(60) and 2PS(n)-AC(60)). The synthesis highlighted the regiospecific multiaddition reaction for C(60) surface functionalization and the Huisgen 1,3-dipolar cycloaddition between alkyne functionalized C(60) and azide functionalized polymer to give rise to shape amphiphiles with precisely defined surface chemistry and molecular topology. When 1,4-dioxane/DMF mixture was used as the common solvent and water as the selective solvent, these shape amphiphiles exhibited versatile self-assembled micellar morphologies which can be tuned by changing various parameters, such as molecular topology, polymer tail length, and initial molecular concentration, as revealed by transmission electron microscopy and light scattering experiments. In the low molecular concentration range of equal or less than 0.25 (wt) %, micellar morphology of the series of PS(n)-AC(60) studied was always spheres, while the series of 2PS(n)-AC(60) formed vesicles. Particularly, PS(44)-AC(60) and 2PS(23)-AC(60) are synthesized as a topological isomer pair of these shape amphiphiles. PS(44)-AC(60) formed spherical micelles while 2PS(23)-AC(60) generated bilayer vesicles under identical conditions. The difference in the self-assembly of PS(n)-AC(60) and 2PS(n)-AC(60) was understood by the molecular shape aspect ratio. The stretching ratio of PS tails decreased with increasing PS tail length in the spherical micelles of PS(n)-AC(60), indicating a micellar behavior that changes from small molecular surfactant-like to amphiphilic block copolymer-like. For the series of PS(n)-AC(60) in the high molecular concentration range [>0.25 (wt) %], their micellar morphological formation of spheres, cylinders, and vesicles was critically dependent upon both the initial molecular concentration and the PS tail length. On the other hand, the series of 2PS(n)-AC(60) remained in the state of bilayer vesicles in the same concentration range. Combining both of the experimental results obtained in the low and high molecular concentrations, a systematic morphological phase diagram was constructed for the series of PS(n)-AC(60) with different PS tail lengths. The versatile and concentration-sensitive phase behaviors of these molecular shape amphiphiles are unique and have not been systematically explored in the traditional surfactants and block copolymers systems.

Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering

“…Whereas the self-assembly of giant surfactants in the bulk and thin-film states is similar to that of block copolymers, they behave like small-molecule surfactants in solution (30,40,52). Not only do they exhibit various micellar morphologies, but also the polymer tails are found to be highly stretched under certain circumstances, a feature reminiscent of small-molecule surfactants.…”

“…Compact and rigid molecular nanoparticles (MNPs) with specific symmetry and precise structure provide access to perfect building blocks for the polar heads (30,35,36). They include, but are not limited to, polyhedral oligomeric silsesquioxane (POSS) (37,38) and [60]fullerene (C 60 ) (39,40) derivatives. In this paper, we report MNP-based giant surfactants (Fig.…”

Synthesis and Self-Assembled Structure of A Cluster-Cluster Hybrid Molecule Composed of POM and POSS Clusters

“…[9～15] 、倍半硅氧烷簇(POSSs) [16,17] 和 富勒烯(C60) [18,19] 等是业已使用的、 具有特殊拓扑结构的 构筑单元. 将它们通过共价键与有机分子 [9,12～15] 、线性 聚合物 [10,11] 、寡聚物 [16] 等结合制备了一系列有趣的称为 形状两亲性分子(Shape Amphiphiles).…”

Highly Efficient Synthesis of Globular (Bola)amphiphilic [5:1]Hexakisadducts of C60

“…Recently, Cheng and co-workers described the synthesis of polystyrene-based amphiphilic [5:1]hexakisadducts. [6] These amphiphiles showed very interesting aggregation properties, which were dependent on both the polystyrene chain length and the molecular concentration. Iehl and Nierengarten developed a click-click approach that allows for the facile synthesis of functionalized [5:1]hexakisadducts.…”

“…Keywords: amphiphiles · dendrimers · fullerenes · NMR spectroscopy · X-ray spectroscopy to the remaining octahedral [6,6] double bond proceeds completely regioselective without any formation of side products. [1] By using fullerene pentakisadducts for a "convergent" reaction the synthesis of 1 was considerably improved both in yield and simplicity of the purification.…”