Lower Critical Solution Temperature (LCST) Phase Behavior of Poly(ethylene oxide) in Ionic Liquids

Lee, Hau Nan; Lodge, Timothy P.

doi:10.1021/jz100617t

Cited by 136 publications

(184 citation statements)

References 37 publications

Supporting

Mentioning

165

Contrasting

Order By: Relevance

“…The copolymer CPT decreased by at least 14 °C when F VBK increased from 2 to 4 mol %; about 18 °C when F VBK increased from 4 to 9 mol %; and for B/V‐11 ( F VBK = 13 mol %), the copolymer was not soluble in the IL at room temperature. Although the phase separation temperature in ILs was reported to be sensitive to molecular weight for various homopolymers, the copolymer composition was considered the dominant factor affecting the transition temperature because the range in molecular weight (ranged from 6.7 to 17.7 kg mol −1 ) of the BzMA/VBK copolymers studied was fairly limited. A similar conclusion was drawn by Ueki et al for BzMA/styrene and BzMA/MMA copolymers, who studied copolymers in the molecular weight range between 13 and 28 kg mol −1 .…”

Section: Resultsmentioning

confidence: 99%

Fluorescent, thermoresponsive copolymers via nitroxide-mediated polymerization: Synthesis and effect of fluorescent groups on phase transitions in an ionic liquid

Zhang

Marić

2013

J. Polym. Sci. Part A: Polym. Chem.

View full text Add to dashboard Cite

Synthesis of poly(benzyl methacrylate) (PBzMA) by nitroxide‐mediated polymerization with a small fraction of fluorescent, controlling comonomer, 9‐(4‐vinylbenzyl)‐9H‐carbazole (VBK, 2–11 mol % in the feed), was studied along with the resulting copolymers' LCST phase behavior in the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium bis(trifluoromethane sulfone)imide. The effectiveness of VBK as a controlling comonomer was demonstrated by a dramatic decrease in the product of average propagation rate constant and average equilibrium constant, , compared to BzMA polymerizations with styrene as comonomer. Linear molecular weight increase with conversion (up to ∼40% conversion), with polydispersities of about 1.34–1.42, and successful chain extensions indicated the copolymerizations were relatively well controlled. The incorporation of fluorescent and solvatophobic VBK units in the BzMA/VBK copolymers not only affected transition temperature and reversibility of the LCST‐type phase separation in the IL, but also led to about a fivefold phase separation‐triggered fluorescent enhancements, likely due to enhanced fluorescence resonance energy transfer from BzMA to VBK being in close proximity during aggregation. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4702–4715

show abstract

Section: Resultsmentioning

confidence: 99%

Fluorescent, thermoresponsive copolymers via nitroxide-mediated polymerization: Synthesis and effect of fluorescent groups on phase transitions in an ionic liquid

Zhang

Marić

2013

J. Polym. Sci. Part A: Polym. Chem.

View full text Add to dashboard Cite

show abstract

“…2,3 In this work, we use atomistic computer simulations to study the phase behavior of PEO in [BMIM] [BF 4 ] .…”

Section: [Emim][bf 4 ]) and 1-butyl-3-methylimidazolium Tetrafluorobomentioning

confidence: 99%

Entropic Mechanism for the Lower Critical Solution Temperature of Poly(ethylene oxide) in a Room Temperature Ionic Liquid

Choi

Yethiraj

2015

ACS Macro Lett.

View full text Add to dashboard Cite

Polymers exhibit interesting phase behavior in room temperature ionic liquids. For example poly(ethylene oxide) (PEO) displays a lower critical solution temperature (LCST) in [BMIM]- [BF 4 ] with a critical temperature and concentration that are only weakly dependent on molecular weight, contrary to the behavior of polymers in other solvents. To shed light on the mechanism of the LCST, we study the phase behavior of PEO in [BMIM][BF 4 ] using molecular dynamics (MD) simulations. The simulations show the signature of a phase transition as the temperature is increased. At low temperatures, interactions similar to a hydrogen bond are found between the imidazolium hydrogen and the PEO oxygen (HI−O Hbond) and the imidazolium hydrogen and the anion fluorines (HI−F H-bond). These interactions stabilize the mixed phase. A potential of mean force (PMF) analysis shows an entropic cost associated with the HI−O H-bond, which makes the bond formation unfavorable at higher temperatures, while the HI−F Hbond does not show a significant temperature dependence: This suggests that LCST phase separation is driven by the entropic penalty of the polymer for a PEO-cation hydrogen bond. We test the effect of scaling the charges on the [BMIM] [BF 4 ]. Interestingly, the scaled charge force-field does not predict a phase separation at any temperature, thus, emphasizing the pitfalls of charge scaling for mixtures. I onic liquids have attracted great attention in the past decade due to their interesting unique properties, such as negligible vapor pressure, high thermal and chemical stability, relatively high ionic conductivity, and nonflammability. These properties have made them an excellent candidate for the next generation solvents that could potentially replace traditional organic solvents in many areas. When mixed with certain polymers, ionic liquids have potential in materials design because the polymers can provide mechanical integrity and structural persistence that ionic liquids lack. 1 These include applications as membranes for fuel cells, polymerized ion gels for gas separation, basis of electromechanical actuators, and electrolytes in lithium batteries. Understanding the phase behavior and miscibility of polymers in ionic liquids is therefore crucial for materials design. There is also fundamental interest because the phase behavior is unusual. Poly(ethylene oxide) (PEO) displays a lower critical solution temperature (LCST) in 1-ethyl-3-methylimidazolium tetrafluoroborate ( [EMIM][BF 4 ]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]).Interestingly, unlike typical polymer solutions, the critical composition occurs at high polymer concentrations, and the critical temperature is insensitive to polymer molecular weight. 2,3 In this work, we use atomistic computer simulations to study the phase behavior of PEO in [BMIM] [BF 4 ] .An LCST usually occurs when both enthalpy of mixing and entropy of mixing are negative. The negative entropy of mixing is often explained either by specific interactions 4−6 or compre...

show abstract

“…41 A mixture of PEO/imidazolium-based ILs containing [BF 4 ] anions has been reported to show similar phase behavior. 42 However, the structural effects of polyethers and ILs on LCST liquidliquid phase separation behavior still remain unclear. In the present study, to understand this unique phase behavior in ILs, we investigate the LCST phase behavior of several polyethers, including PEGE, in ILs and the structural effects of ILs on phase separation.…”

Section: Introductionmentioning

confidence: 99%

Structural effects of polyethers and ionic liquids in their binary mixtures on lower critical solution temperature liquid-liquid phase separation

Kodama

Tsuda

Niitsuma

et al. 2011

Polym J

103

View full text Add to dashboard Cite

The solubility and phase behavior of five polyethers (poly(ethylene oxide), poly(glycidyl methyl ether), poly(ethyl glycidyl ether), poly(ethoxyethyl glycidyl ether) and poly(propylene oxide)) in 14 different room-temperature ionic liquids (ILs) were studied by changing the structures of polyethers and the cations and anions in the ILs. Certain combinations of a polyether and an IL binary mixture exhibited lower critical solution temperature (LCST) phase behavior. For ILs containing the same anions, the polyethers were highly soluble in imidazolium-or pyridinium-based ILs, whereas they were insoluble in ammonium-or phosphonium-based ILs. An increase in length of the alkyl chain in the imidazolium cation and an increase in polarity of the polyethers resulted in a higher LCST phase separation temperature, whereas substitution of the hydrogen atoms on the imidazolium ring by methyl groups resulted in a lower LCST phase separation temperature. The hydrogen bonding interaction between the oxygen atoms in the polyethers and the aromatic hydrogen atoms on the cations in the ILs had an important role in the LCST phase behavior of the mixtures. Miscibility of the mixtures was also affected by the Lewis basicity of the anions in the ILs.

show abstract

Lower Critical Solution Temperature (LCST) Phase Behavior of Poly(ethylene oxide) in Ionic Liquids

Cited by 136 publications

References 37 publications

Fluorescent, thermoresponsive copolymers via nitroxide-mediated polymerization: Synthesis and effect of fluorescent groups on phase transitions in an ionic liquid

Fluorescent, thermoresponsive copolymers via nitroxide-mediated polymerization: Synthesis and effect of fluorescent groups on phase transitions in an ionic liquid

Entropic Mechanism for the Lower Critical Solution Temperature of Poly(ethylene oxide) in a Room Temperature Ionic Liquid

Structural effects of polyethers and ionic liquids in their binary mixtures on lower critical solution temperature liquid-liquid phase separation

Contact Info

Product

Resources

About