Effect of supercritical carbon dioxide on molecular aggregation states of side chains of semicrystalline poly{2-(perfluorooctyl)ethyl acrylate} brush thin films

Hiroki Yamaguchi, Peter Gin, Hiroshi Arita, Motoyasu Kobayashi, Steve Bennett, Sushil K. Satija, Mitsunori Asada, Tadanori Koga, Atsushi Takahara

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Abstract

We report a carbon dioxide-based approach to induce highly ordered molecular aggregation states of perfluoroalkyl (Rf) chains of densely-grafted poly{2-(perfluorooctyl)ethyl acrylate} (poly(FA-C8)) brush in place of conventional thermal annealing. Poly(FA-C8) brush films of 40 nm thickness were prepared by surface-initiated atom transfer radical polymerization. In-situ neutron reflectivity measurements for the poly(FA-C8) brush films under the isothermal condition of T = 309 K, which is below the bulk melting temperature (Tm = 348 K), elucidated large expansion of polymer chains due to sorption of CO2 molecules. Comparison of the swelling behavior with an amorphous poly{2-(perfluorobutyl) ethyl acrylate} brush thin film clarified that the sorption of CO2 molecules results in the melting of the semicrystalline poly(FA-C8) brush at P > 4.1 MPa. In addition, by using out-of-plane grazing incidence wide-angle X-ray diffraction, it was found that subsequent slow quench from P > 4.1 MPa induces rearrangement of the rigid rod-like Rf groups, forming highly ordered molecular aggregation structures similar to those via a conventional thermal process. The appropriate CO2 process conditions for the effective induction of the highly ordered structures of the rigid R f groups are discussed in detail.

Original languageEnglish
Pages (from-to)4778-4785
Number of pages8
JournalRSC Advances
Volume3
Issue number14
DOIs
Publication statusPublished - Apr 14 2013

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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