Abstract
We have 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) d8-1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (d8-[C2mIm+][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 Tc. Furthermore, we evaluated the enthalpic and entropic contributions to the effective interaction parameter χeff of PPhEtMA in [C2mIm+][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 χeff was smaller than the previously reported value for a thermo-responsive polymer in an aqueous system. It was found out that the strong dependence of Tc on the chemical structure in IL systems originated from the relatively smaller temperature dependence of χeff.
Original language | English |
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Pages (from-to) | 17881-17889 |
Number of pages | 9 |
Journal | Physical Chemistry Chemical Physics |
Volume | 18 |
Issue number | 27 |
DOIs | |
State | Published - 2016 |
Funding
This work has been financially supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (No. 22245018 to M. S.). The experiment (IPTS12408.1) using the General-Purpose SANS (CG-2) at Oak Ridge National Laboratory was supported by the US-Japan Cooperative Program on Neutron Scattering. Travel expenses for the experiment were also supported by General User Program for Neutron Scattering Experiments, Institute for Solid State Physics, The University of Tokyo (proposal no. 14906), at JRR-3, Japan Atomic Energy Agency, Tokai, Japan. The High Flux Isotope Reactor and beamline CG2 of ORNL was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. K. H. was supported by Japan Society for the Promotion of Science through Program for Leading Graduate Schools (MERIT).
Funders | Funder number |
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General-Purpose SANS | CG-2 |
Japan Atomic Energy Agency, Tokai, Japan | |
Scientific User Facilities Division | |
US-Japan | |
U.S. Department of Energy | |
Basic Energy Sciences | |
Japan Society for the Promotion of Science | 26620164, 15H05495, 15H05758, 16H02277 |
Ministry of Education, Culture, Sports, Science and Technology | 22245018, IPTS12408.1 |
University of Tokyo | 14906 |