Surface modification with cross-linked random copolymers: Minimum effective thickness

Du Yeol Ryu, Jia Yu Wang, Kristopher A. Lavery, Eric Drockenmuller, Sushil K. Satija, Craig J. Hawker, Thomas P. Russell

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Abstract

Ultrathin films of benzocyclobutene (BCB)-functionalized random copolymer with styrene and methyl methacrylate, P(S-r-BCB-r-MMA), with thicknesses ranging from 0 to 10.5 nm, were thermally cross-linked on Si substrates. The penetration of deuterated PMMA (dPMMA) into the P(S-r-BCB-r-MMA) films and the microdomain orientation of PS-b-PMMA diblock copolymers on P(S-r-BCB-r-MMA) coated substrates were investigated by neutron reflectivity (NR) and scanning force microscopy (SFM), respectively. NR measurements on bilayers of dPMMA on cross-linked P(S-r-BCB-r-MMA) showed that the neutron scattering length density (SLD) at the substrate was equal to that of P(S-r-BCB-r-MMA) if the P(S-r-BCB-r-MMA) film was thicker than ∼5.5 nm. With decreasing thickness of the P(S-r-BCB-r-MMA) film, the SLD at the substrate increased, characteristic of an increasing penetration of the dPMMA. When thin films of PS-b-PMMA diblock copolymer having cylindrical microdomains are placed on surfaces modified with cross-linked films of P(S-r-BCB-r-MMA) thinner than ∼5.5 nm, the cylindrical microdomains orient parallel to the surface, whereas for thicker films, the microdomains orient normal to the surface. Both of these results indicate that interfacial interactions are screened when the P(S-r-BCB-r-MMA) film is thicker than ∼5.5 nm.

Original languageEnglish
Pages (from-to)4296-4300
Number of pages5
JournalMacromolecules
Volume40
Issue number12
DOIs
Publication statusPublished - 2007 Jun 12

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All Science Journal Classification (ASJC) codes

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

Cite this

Ryu, D. Y., Wang, J. Y., Lavery, K. A., Drockenmuller, E., Satija, S. K., Hawker, C. J., & Russell, T. P. (2007). Surface modification with cross-linked random copolymers: Minimum effective thickness. Macromolecules, 40(12), 4296-4300. https://doi.org/10.1021/ma062939w