Direct Observation of Topological Defects in Striped Block Copolymer Discs and Polymersomes

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  • Tina I. Gröschel, University of Duisburg-Essen
  • ,
  • Chin Ken Wong, University of Münster
  • ,
  • Johannes S. Haataja, Cambridge University
  • ,
  • Marcelo A. Dias
  • Andre H. Gröschel, University of Duisburg-Essen, University of Münster

Topology and defects are of fundamental importance for ordered structures on all length scales. Despite extensive research on block copolymer self-assembly in solution, knowledge about topological defects and their effect on nanostructure formation has remained limited. Here, we report on the self-assembly of block copolymer discs and polymersomes with a cylinder line pattern on the surface that develops specific combinations of topological defects to satisfy the Euler characteristics for closed spheres as described by Gauss-Bonnet theorem. The dimension of the line pattern allows the direct visualization of defect emergence, evolution, and annihilation. On discs, cylinders either form end-caps that coincide with λ+1/2 disclinations or they bend around τ+1/2 disclinations in 180° turns (hairpin loops). On polymersomes, two λ+1/2 defects connect into three-dimensional (3D) Archimedean spirals, while two τ+1/2 defects form 3D Fermat spirals. Electron tomography reveals two complementary line patterns on the inside and outside of the polymersome membrane, where λ+1/2 and τ+1/2 disclinations always eclipse on opposing sides ("defect communication"). Attractive defects are able to annihilate with each other into +1 disclinations and stabilize anisotropic polymersomes with sharp tips through screening of high-energy curvature. This study fosters our understanding of the behavior of topological defects in self-assembled polymer materials and aids in the design of polymersomes with preprogrammed shapes governed by synthetic block length and topological rules.

OriginalsprogEngelsk
TidsskriftACS Nano
Vol/bind14
Nummer4
Sider (fra-til)4829-4838
Antal sider10
ISSN1936-0851
DOI
StatusUdgivet - 2020

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