title: Aqueous self-assembly of giant bottlebrush block copolymer surfactants as shape-tunable building blocks.
abstract: Programmed self-assembly of well-defined molecular building blocks enables the fabrication of precisely structured nanomaterials. In this work, we explore a new class of giant polymeric surfactants (Mn = (0.7-4.4) × 10(6) g/mol) with bottlebrush architecture and show that their persistent molecular shape leads to the formation of uniform aggregates in a predictable manner. Amphiphilic bottlebrush block copolymers containing polylactide (PLA) and poly(ethylene oxide) (PEO) side chains were synthesized by a grafting-from method, and their self-assembly in aqueous environment was studied by cryogenic transmission electron microscopy. The produced micelle structures with varying interfacial curvatures and core radii (19-55 nm) boasted rod-like hydrophilic PEO brushes protruding from the hydrophobic PLA cores normal to the interface. Highly uniform spherical micelles with low dispersities were obtained from bottlebrush amphiphiles with packing parameters of ∼0.3, estimated from the polymer structural data. Long cylindrical micelles and other nonspherical aggregates were observed for the first time for compositionally less asymmetric bottlebrush surfactants. Critical micelle concentration values of 1 nM, measured for PEO-rich bottlebrush amphiphiles, indicated an enhanced thermodynamic stability of the produced micelle aggregates. Shape-dependent assembly of bottlebrush surfactants allows for the rational fabrication of a range of micelle structures in narrow morphological windows.
authors.affiliation: Department of Chemistry, University at Buffalo, The State University of New York , Buffalo, New York 14260-3000, United States.
authors.forename: Ryan
authors.initials: R
authors.lastname: Fenyves
authors.forename: Marc
authors.initials: M
authors.lastname: Schmutz
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Horner
authors.forename: Frank V
authors.initials: FV
authors.lastname: Bright
authors.forename: Javid
authors.initials: J
authors.lastname: Rzayev
mesh_terms: D046911:Macromolecular Substances; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D012997:Solvents; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water
chemical_list: D046911:Macromolecular Substances; D011108:Polymers; D012997:Solvents; D013501:Surface-Active Agents; D014867:Water