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Theself-assembly behaviors of fluorinated polyhedral oligomeric silsesquioxane(FPOSS)-based giant surfactants, consisting of an FPOSS cage and apolystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer tail, are studied in the bulk.The tethering point of the FPOSS cage on the PS-b-PEO diblock copolymer chain can be controlled precisely either atthe end of the PS block or the junction point between the PS and PEOblocks, resulting in topological isomer pairs with almost identicalchemical compositions but different architectures. Phase separationbetween the FPOSS head and the block copolymer tail creates a spatiallyconfined environment for the PS-b-PEO component,which are uniformly end- or junction-point-immobilized on the FPOSSlayer, providing a unique model system to study phase behaviors andchain conformation of tethered diblock copolymer in the condensedstate. The polymer tails are highly stretched because the cross-sectionalarea of FPOSS head is smaller than that of the unperturbed block copolymertail, which facilitates further phase separation between the low molecularweight PS and PEO blocks and leads to the formation of hierarchicallamellar structures among three mutually immiscible components. [ABSTRACT FROM AUTHOR]

Controlling self-assembled nanostructures in thin films allows the bottom-up fabrication of ordered nanoscale patterns. Here we report the unique thickness-dependent phase behavior in thin films of a bolaform-like giant surfactant, which consists of butyl- and hydroxyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS and DPOSS) cages telechelically located at the chain ends of a polystyrene (PS) chain with 28 repeating monomers on average. In the bulk, BPOSS-PS28-DPOSS forms a double gyroid (DG) phase. Both grazing incidence small-angle X-ray scattering and transmission electron microscopy techniques are combined to elucidate the thin film structures. Interestingly, films with thicknesses thinner than 200 nm exhibit an irreversible phase transition from hexagonal perforated layer (HPL) to compressed hexagonally packed cylinders (c-HEX) at 130 °C, while films with thickness larger than 200 nm show an irreversible transition from HPL to DG at 200 °C. The thickness-controlled transition pathway suggests possibilities to obtain diverse patterns via thin film self-assembly. [ABSTRACT FROM AUTHOR]

Phase behaviors of two series of giant surfactants consisting of a hydrophilic [60]fullerene (AC60) molecular nanoparticle (MNP) tethered to a polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer were investigated. The physical location of AC60 MNP was specifically designed to be at the end of the PS block (AC60-PS-PEO) or at the junction point [PS-(AC60)-PEO] between the PS and PEO blocks. Self-assemblies of these two series of giant surfactants in the bulk revealed that the incorporation of AC60 MNPs leads to nanophase separation of originally disordered PS-b-PEO block copolymers having their block lengths shorter than the limiting value for the nanophase separation in the PS-b-PEO precursors. Based on small-angle X-ray scattering and transmission electron microscopy results, three ordered nanostructures were observed in these two series of giant surfactants, including lamellae, double gyroids, and cylinders, all of which possess domain sizes smaller than 10 nm. Two pairs of topological isomers, AC60-PS50-PEO45 and PS50-(AC60)-PEO45 as well as AC60-PS78-PEO45 and PS78-(AC60)-PEO45, were explicitly investigated to reveal the topological effect on self-assembly behaviors of these giant surfactants. The results provided evidence of the physical location and distribution of the AC60 MNPs within the nanophase-separated domains and demonstrated abilities to stabilize the different structures via topological variations. This study thus affords an efficient and practical strategy for the design and preparation of giant surfactants to construct ordered nanostructures for technologically relevant applications. [ABSTRACT FROM AUTHOR]

We report the solution self-assembly of an ABC block terpolymer consisting of a polystyrene-blockfopoly(ethylene oxide) (PS-b-PEO) diblock copolymer tail tethered to a fluorinated polyhedral oligomeric silsesquioxane (FPOSS) cage in 1,4-dioxane/water. With increasing water content, abundant unconventional morphologies, including circular cylinders, two-dimensional hexagonally patterned colloidal nanosheets, and laterally patterned vesicles, are sequentially observed. The formation of toroids is dominated by two competing free energies: the end-cap energy of cylinders and the bending energy to form the circular structures. Incorporating the superhydrophobic FPOSS cages enhances the end-cap energy and promotes toroid formation. Lateral aggregation and fusion of the cylinders results in primitive nanosheets that are stabilized by the thicker rims to partially release the rim-cap energy. Rearrangement of the parallel-aligned FPOSS cylindrical cores generates hexagonally patterned nanosheets. Further increasing the water content induces the formation of vesicles with nanopatterned walls. [ABSTRACT FROM AUTHOR]

The engineering of structures across different length scales is central to the design of novel materials with controlled macroscopic properties. Herein, we introduce a unique class of self-assembling materials, which are built upon shapeand volume-persistent molecular nanoparticles and other structural motifs, such as polymers, and can be viewed as a size-amplified version of the corresponding small-molecule counterparts. Among them, "giant surfactants" with precise molecular structures have been synthesized by "clicking" compact and polar molecular nanoparticles to flexible polymer tails of various composition and architecture at specific sites. Capturing the structural features of small-molecule surfactants but possessing much larger sizes, giant surfactants bridge the gap between small-molecule surfactants and block copolymers and demonstrate a duality of both materials in terms of their self-assembly behaviors. The controlled structural variations of these giant surfactants through precision synthesis further reveal that their selfassemblies are remarkably sensitive to primary chemical structures, leading to highly diverse, thermodynamically stable nanostructures with feature sizes around 10 nm or smaller in the bulk, thin-film, and solution states, as dictated by the collective physical interactions and geometric constraints. The results suggest that this class of materials provides a versatile platform for engineering nanostructures with sub-10-nm feature sizes. These findings are not only scientifically intriguing in understanding the chemical and physical principles of the self-assembly, but also technologically relevant, such as in nanopatterning technology and microelectronics. [ABSTRACT FROM AUTHOR]