Anomalous Confinement Slows Surface Fluctuations of Star Polymer Melt Films

Fan Zhang, Qiming He, Yang Zhou, Suresh Narayanan, Chao Wang, Bryan D. Vogt, Mark D. Foster

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The unusually large film thickness at which confinement effects manifest themselves in surface fluctuations of unentangled four-arm star polymers has been defined using film thicknesses from 10Rg to 107Rg. For 15k four-arm star polystyrene (SPS), confinement appears at a thickness between 112 nm (40Rg) and 72 nm (26Rg), which is remarkably larger than the thicknesses at which confinement appears for unentangled 6k linear (<15 nm, <7Rg) and 6k and 14k cyclic (24 and 22 nm, respectively) polystyrenes. Data for 15k star films can be rationalized using a two-layer model with a 17 nm (6Rg) thick highly viscous layer at the substrate, which is significantly thicker than the 1Rg thick "irreversibly adsorbed" layer. For a 29 nm (10Rg) thick film, more striking confinement occurs due to the combined influence of both interfaces. These results underscore the extraordinary role long-chain branching plays in dictating surface fluctuations of thin films.

Original languageEnglish (US)
Pages (from-to)834-839
Number of pages6
JournalACS Macro Letters
Issue number7
StatePublished - Jul 17 2018

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry


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