Friction behavior of high-density poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous media

Motoyasu Kobayashi, Yuki Terayama, Nao Hosaka, Masataka Kaido, Atsushi Suzuki, Norifumi Yamada, Naoya Torikai, Kazuhiko Ishihara, Atsushi Takahara

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226 Citations (Scopus)


Super-hydrophilic polymer brushes were prepared by surface-initiated atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) on initiator-immobilized silicon wafers. The graft density was estimated to be ca. 0.22 chains nm-2 based on the linear relationship between Mn and the layer thickness. The contact angle against water was very low, and air bubbles in water hardly attached onto the brush surface, indicating a super-hydrophilic surface. Neutron reflectivity measurements of the poly(MPC) brush showed that the grafting polymer chains extended a fair amount in the vertical direction from the substrate in a good solvent such as water, while they shrunk in a poor solvent. Frictional properties of the poly(MPC) brushes were characterized by sliding a glass ball probe in air and various solvents under a load of 0.49 N at a sliding velocity of 90 mm min-1. An extremely low friction coefficient of the poly(MPC) brush was observed in humid atmosphere because water molecules adsorbed into the brush layer acted as a lubricant.

Original languageEnglish
Pages (from-to)740-746
Number of pages7
JournalSoft Matter
Issue number6
Publication statusPublished - 2007

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Condensed Matter Physics


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