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Title: SANS study on the solvated structure and molecular interactions of a thermo-responsive polymer in a room temperature ionic liquid

Here, we utilized small-angle neutron scattering (SANS) to quantitatively characterize the LCST-type phase behavior of the poly(benzyl methacrylate) (PBnMA) derivative poly(2-phenylethyl methacrylate) (PPhEtMA) in the deuterated ionic liquid (IL) d 8-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (d 8-[C 2mIm +][TFSA -]). The SANS curves showed a discontinuous change from those characteristics of dispersed polymer chains to those of large aggregates of PPhEtMA chains suspended in the IL solution, indicating that phase separation occurs discontinuously at T c. We also evaluated the enthalpic and entropic contributions to the effective interaction parameter χ eff of PPhEtMA in [C 2mIm +][TFSA -] and compared them with those of PBnMA. The absolute value of the enthalpic contribution observed for PPhEtMA was smaller than that for PBnMA. This difference in the enthalpic term can be attributed to the unfavorable interaction between the IL and the alkyl group in the side chain of PPhEtMA. In addition, the temperature dependence of χ eff was smaller than the previously reported value for a thermo-responsive polymer in an aqueous system. Finally, it was found out that the strong dependence of T c on the chemical structure in IL systems originated from the relatively smaller temperature dependence of χ eff.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4] ;  [1]
  1. Univ. of Tokyo (Japan). Inst. for Solid State Physics
  2. Yamaguchi Univ., Ube (Japan)
  3. National Inst. for Materials Science (NIMS), Tsukuba (Japan). Polymer Materials Unit
  4. Yokohama National Univ., Hodogaya-ku (Japan)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 18; Journal Issue: 27; Journal ID: ISSN 1463-9076
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier: