Ultrastable Glassy Polymer Films with an Ultradense Brush Morphology

Biao Zuo, Cheng Li, Quanyin Xu, Katelyn Randazzo, Naisheng Jiang, Xinping Wang, Rodney D. Priestley

Research output: Contribution to journalArticlepeer-review

Abstract

Glassy polymer films with extreme stability could enable major advancements in a range of fields that require the use of polymers in confined environments. Yet, from a materials design perspective, we now know that the glass transition temperature (Tg) and thermal expansion of polymer thin films can be dramatically different from those characteristics of the bulk, i.e., exhibiting confinement-induced diminished thermal stability. Here, we demonstrate that polymer brushes with an ultrahigh grafting density, i.e., an ultradense brush morphology, exhibit a significant enhancement in thermal stability, as manifested by an exceptionally high Tg and low expansivity. For instance, a 5 nm thick polystyrene brush film exhibits an ∼75 K increase in Tg and ∼90% reduction in expansivity compared to a spin-cast film of similar thickness. Our results establish how morphology can overcome confinement and interfacial effects in controlling thin-film material properties and how this can be achieved by the dense packing and molecular ordering in the amorphous state of ultradense brushes prepared by surface-initiated atom transfer radical polymerization in combination with a self-assembled monolayer of initiators.

Original languageEnglish (US)
Pages (from-to)9568-9576
Number of pages9
JournalACS Nano
Volume15
Issue number6
DOIs
StatePublished - Jun 22 2021

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Keywords

  • glass transition
  • polymer brushes
  • thermal expansion
  • thin polymer films
  • ultrastable polymer glasses

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