title: Unique toroidal morphology from composition and sequence control of triblock copolymers.
abstract: The mechanism by which the unique toroidal supramolecular assemblies were formed for triblock copolymers of acrylic acid (AA), methyl acrylate (MA), and styrene (S), PAA99-b-PMA73-b-PS66, was probed in this study by investigating the influences of the block copolymer compositions and sequences. Two triblock copolymers, PAA99-b-PMA73-b-PS66 and PAA99-b-PS76-b-PMA62, and two diblock copolymers, PAA99-b-PMA155 and PAA99-b-PS133, were studied under experimental solution-state conditions that involved a range of solvent/nonsolvent (tetrahydrofuran/water) compositions, each in the presence of 2,2'-(ethylenedioxy)bis(ethylamine). The resulting morphologies were determined by transmission electron microscopy. The failures to afford toroidal supramolecular assemblies from both diblock copolymers having comparable lengths of the total hydrophobic chain segment, either entirely PMA or entirely PS, and from the triblock copolymer having a reversed connection sequence for the hydrophobic (PMA and PS) segments demonstrate the unique self-assembly behaviors of triblock copolymers and the importance of the block copolymer sequence.
authors.affiliation: Center for Materials Innovation and Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Chen
authors.forename: Honggang
authors.initials: H
authors.lastname: Cui
authors.forename: Kelly
authors.initials: K
authors.lastname: Hales
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Li
authors.forename: Kai
authors.initials: K
authors.lastname: Qi
authors.forename: Darrin J
authors.initials: DJ
authors.lastname: Pochan
authors.forename: Karen L
authors.initials: KL
authors.lastname: Wooley
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D016503:Drug Delivery Systems; D004492:Edetic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D011108:Polymers; D011109:Polymethacrylic Acids; D011137:Polystyrenes; C006903:carbopol 940; C026058:EDDA; D004492:Edetic Acid