Spontaneously formed hydrophilic surfaces by segregation of block copolymers with water-soluble blocks

Hideaki Yokoyama, Takayuki Miyamae, Seok Han, Takashi Ishizone, Keiji Tanaka, Atsushi Takahara, Naoya Torikai

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

A block copolymer of deuterated polystyrene (dPS) and 2-[2-(2-methoxyethoxy)ethoxy]ethyl methacrylate (PME3MA) spontaneously exposes the PME3MA block, which is soluble in water, to the surface in a vacuum. dPS-PME3MA mixed with polystyrene (PS) segregates to the PS surface and changes the hydrophobic PS surface into hydrophilic surface. Neutron reflectivity, X-ray photoelectron spectroscopy, and dynamic secondary ion mass spectrometry probe the surface segregation of dPS-PME3MA to the surface of PS due to its PME3MA block. Sum-frequency generation vibrational spectroscopy detects exclusively the triethylene oxide (3EO) side chains of PME3MA regardless of a small fraction of dPS-PME3MA in the mixture, suggesting the conformation of the side chains influencing the segregation behavior. Because of the amphiphilic character of the methoxy-terminated 3EO side chains, the PME3MA block exposes the terminal methyl groups of the side chains to the surface to reduce the free energy of the system. However, such a hydrophobic methyl surface layer barely covers the EO part of the side chains; the surface quickly reconstructs and becomes hydrophilic upon contact with water. This is a technologically important demonstration of converting a hydrophobic polymer surface to a hydrophilic surface just by adding a small amount of block copolymer.

Original languageEnglish
Pages (from-to)5180-5189
Number of pages10
JournalMacromolecules
Volume38
Issue number12
DOIs
Publication statusPublished - Jun 14 2005

All Science Journal Classification (ASJC) codes

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

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