title: Reversible stimuli-responsive nanostructures assembled from amphiphilic block copolymers.
abstract: We present a novel route to assemble perpendicular cylinders by converting an asymmetric diblock copolymer from poly(styrene-b-tert-butyl acrylate) (PS-b-PtBA) to poly(styrene-b-acrylic acid) (PS-b-PAA) using an autocatalytic reaction. Upon exposure of the films of PS-b-PAA to water, PAA cylinders constrained by the continuous, glassy PS phase protrude 10 nm above the surface and swell laterally to form mushroom caps, rendering the entire surface hydrophilic. Upon annealing, the original nanostructures re-form demonstrating reversibility of swelling. Because of their stimuli-responsive behavior, these nanoscale materials are excellent candidates for sensors and microfluidic applications.
authors.affiliation: Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6272, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Fu
authors.forename: Michael
authors.initials: M
authors.lastname: Fryd
authors.forename: Song
authors.initials: S
authors.lastname: Xu
authors.forename: Bradford B
authors.initials: BB
authors.lastname: Wayland
authors.forename: Karen I
authors.initials: KI
authors.lastname: Winey
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Composto
mesh_terms: D000179:Acrylates / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D018625:Microscopy, Atomic Force / Q000379:methods; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011137:Polystyrenes / Q000138:chemical synthesis* / Q000737:chemistry*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000179:Acrylates; D011137:Polystyrenes; C509855:poly(styrene-b-acrylic acid); C509854:poly(styrene-b-tert-butylacrylate)