Imaging of phase segregation in gradient copolymers: Island and hole surface topography

Michelle M. Mok, John M. Torkelson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Application of traditional block copolymer microscopy techniques to gradient copolymers yields limited results, due to the low compositional contrast provided from the sinusoidal composition profiles of their phase segregated nanostructures. In contrast, optical microscopy and profilometry allow for the first direct visualization of their phase segregation properties through surface features formed in annealed thin films. Three comonomer systems are studied; one block and one gradient copolymer are compared for each system. Island/hole topography is observed in all block cases. Of the three gradient copolymers, one showed no pattern development and two showed emergence of island/hole patterns, which coarsen over initial annealing and then appear to anneal away. These results are related to the lower driving force for phase segregation from gradient sequencing, which lowers the potential of gradient copolymers to form island/hole patterns and also to pin any patterns formed.

Original languageEnglish (US)
Pages (from-to)189-197
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number3
StatePublished - Feb 1 2012


  • block copolymers
  • phase separation
  • self-assembly
  • surfaces
  • thin films

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


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