Small-angle neutron scattering study on microstructure of poly(N-isopropylacrylamide)-block-poly(ethylene glycol) in water

Ryuhei Motokawa, Annaka Masahiko, Takayuki Nakahira, Satoshi Koizumi

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Abstract

By employing small-angle neutron scattering (SANS), we investigated the microstructures of, poly(N-isopropylacrylamide) (PNIPA)-block-poly(ethylene glycol) (PEG) (NE) in deuterated water D 2O, as related to macroscopic behaviors of fluidity, turbidity and synerisis. SANS revealed following results: (i) microphase separation occurs at around above 17°C in a temperature range of transparent sol below 30°C. In the microdomain appeared in the transparent sol state, both block chains of PNIPA and PEG are swollen by water; (ii) for the NE solution of polymer concentration W p > 3.5% (w/v), corresponding to opaque gel above 30°C, a percolated structure, i.e., network-like domain is formed by NE as a result of macrophase separation due to dehydration of the PNIPA chains. As the temperature increases toward 40°C, the network domain is squeezed along a direction parallel to the NE interface, which leads to increase of the interfacial thickness given by swollen PEG chains and to the macroscopic synerisis behavior.

Original languageEnglish
Pages (from-to)213-219
Number of pages7
JournalColloids and Surfaces B: Biointerfaces
Volume38
Issue number3-4 SPEC. ISS.
DOIs
Publication statusPublished - Nov 15 2004

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All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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