title: Geometry induced sequence of nanoscale Frank-Kasper and quasicrystal mesophases in giant surfactants.
abstract: Frank-Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with "soft" spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Kan
authors.initials: K
authors.lastname: Yue
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Marson
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
authors.forename: Jinlin
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Jiahao
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
authors.forename: Xuesheng
authors.initials: X
authors.lastname: Yan
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Kan
authors.initials: K
authors.lastname: Wu
authors.affiliation: Department of Chemistry, The University of Akron, Akron, OH 44325.
authors.forename: Zaihong
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.
authors.forename: Wei
authors.identifier: 0000-0002-9321-6411
authors.initials: W
authors.lastname: Zhang
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
authors.forename: Peihong
authors.initials: P
authors.lastname: Ni
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909.|Department of Chemistry, The University of Akron, Akron, OH 44325.
authors.forename: Chrys
authors.initials: C
authors.lastname: Wesdemiotis
authors.affiliation: Key Laboratory of Polymer Chemistry & Physics of Ministry of Education, Centre for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China; wenbin@pku.edu.cn sglotzer@umich.edu scheng@uakron.edu.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109; wenbin@pku.edu.cn sglotzer@umich.edu scheng@uakron.edu.|Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Glotzer
authors.affiliation: Department of Polymer Science, College of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909; wenbin@pku.edu.cn sglotzer@umich.edu scheng@uakron.edu.
authors.forename: Stephen Z D
authors.initials: SZ
authors.lastname: Cheng
keywords: Frank–Kasper phases; POSS; giant surfactants; quasicrystal phases; self-assembly