Spherically Symmetric Solvent is Sufficient to Explain the LCST Mechanism in Polymer Solutions

Bharadwaj, Swaminath; Kumar, P. B. Sunil; Komura, Shigeyuki; Deshpande, Abhijit P.

doi:10.1002/mats.201600073

Cited by 4 publications

(14 citation statements)

References 50 publications

(105 reference statements)

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“…All the studies were performed on a N = 200 chain in 5000 (N s +N c ) beads of the solvent mixture. In our previous work on a polymer in a pure solvent, 46 we observed a decrease in R g with temperature for as = 1.7, 1.8. Hence, the simulations were performed on three different polymer-solvent interactions; as = ac = 1.7, 1.8, 2.0 at three different temperatures (T = 0.55, 0.65, 0.75).…”

Section: Aa Hh Ss(cc) Ah Hs(hc) As(ac) Csmentioning

confidence: 67%

“…The phase transition occurs when x > 1. In our previous study, 46 we showed that the LCST in the case of pure solvent is dependent on the competition between the mean energy difference between the bulk and the bound solvent (U BS − U US ), and the bound solvent…”

Section: B Theoretical Modelmentioning

confidence: 99%

“…The LCST behavior has been modeled by using the Kolomeisky-Widom (KW) potential. 46,49 In the KW-model, solvent molecules form a onedimensional lattice with a nearest neighbor interaction and each solvent molecule can exist in q different states. Depending on the interaction between the neighboring solvent molecules, they can be classified into one Bound State (BS) and q −1 Unbound States (US) with energy w and u, respectively.…”

Section: B Theoretical Modelmentioning

confidence: 99%

“…The expression for B KW has been derived in our previous work (see SI for details). 46 We define dimensionless quantities,…”

Section: B Theoretical Modelmentioning

confidence: 99%

“…Following our earlier study on the LCST of polymer in pure solvent, 46 the polymer is modeled as a linear chain consisting of alternating solvophobic and amphiphilic beads (N total beads, N/2 solvophobic, and N/2 amphiphilic beads). To avoid any temperature dependence on the interaction potentials, the solvent-cosolvent mixture has been included explicitly by N s solvent and N c cosolvent beads.…”

Section: A Coarse-grained Explicit Solvent Simulationsmentioning

confidence: 99%

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Kosmotropic effect leads to LCST decrease in thermoresponsive polymer solutions

Bharadwaj

Kumar

Komura

et al. 2018

The Journal of Chemical Physics

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We study the phenomena of decrease in lower critical solution temperature (LCST) with addition of kosmotropic (order-making) cosolvents in thermoresponsive polymer solutions. A combination of explicit solvent coarse-grained simulations and mean-field theory has been employed. The polymer-solvent LCST behavior in the theoretical models has been incorporated through the Kolomeisky-Widom solvophobic potential. Our results illustrate how the decrease in the LCST can be achieved by the reduction in the bulk solvent energy with the addition of cosolvent. It is shown that this effect of cosolvent is weaker with an increase in polymer hydrophilicity which can explain the absence of a LCST decrease in poly(N,N-diethylacrylamide), water, and methanol systems. The coarse-grained nature of the models indicates that a mean energetic representation of the system is sufficient to understand the phenomena of LCST decrease.

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Section: Aa Hh Ss(cc) Ah Hs(hc) As(ac) Csmentioning

confidence: 67%

Section: B Theoretical Modelmentioning

confidence: 99%

Section: B Theoretical Modelmentioning

confidence: 99%

“…The expression for B KW has been derived in our previous work (see SI for details). 46 We define dimensionless quantities,…”

Section: B Theoretical Modelmentioning

confidence: 99%

Section: A Coarse-grained Explicit Solvent Simulationsmentioning

confidence: 99%

See 3 more Smart Citations

Kosmotropic effect leads to LCST decrease in thermoresponsive polymer solutions

Bharadwaj

Kumar

Komura

et al. 2018

The Journal of Chemical Physics

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Phase Separation of Aqueous Poly(diisopropylaminoethyl methacrylate) upon Heating

et al. 2021

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Poly(diisopropylaminoethyl methacrylate) (PDPA) is a pHand thermally responsive water-soluble polymer. This study deepens the understanding of its phase separation behavior upon heating. Phase separation upon heating was investigated in salt solutions of varying pH and ionic strength. The effect of the counterion on the phase transition upon heating is clearly demonstrated for chloride-, phosphate-, and citrate-anions. Phase separation did not occur in pure water. The buffer solutions exhibited similar cloud points, but phase separation occurred in different pH ranges and with different mechanisms. The solution behavior of a block copolymer comprising poly(dimethylaminoethyl methacrylate) (PDMAEMA) and PDPA was investigated. Since the PDMAEMA and PDPA blocks phase separate within different pH-and temperature ranges, the block copolymer forms micelle-like structures at high temperature or pH.

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Water/Cosolvent Attraction Induced Phase Separation: A Molecular Picture of Cononsolvency

Zuo

Jiao

et al. 2019

Macromolecules

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Cononsolvency is a phenomenon for which the solubility of a macromolecule decreases or even vanishes in the mixture of two good solvents. Although it has been widely applied in physicochemical, green chemical and pharmaceutical industry, its origin is still under active debate. Here, by using combined neutron total scattering, deuterium-labelling and all-atom molecular dynamic simulations, we demonstrated that it is the strong water/cosolvent attraction that leads to the cononsolvency. The combined approach presented here has opened a new route for investigating the most probable allatom structure in macromolecular solutions and the thermodynamic origin of solubilities.The solubility of macromolecules is of fundamental importance in many scientific disciplines and industrial applications. Unfortunately, the existing theoretical framework to describe the solvation of macromolecules are constructed primarily based on empirical observations without knowing the real solubility parameters, which cannot be measured directly 1, 2 . One problematic consequence of this inability to directly measure the real macromolecular solubility parameter, is that several important dissolution phenomena cannot then explained in the existing framework of understanding; cononsolvency is a typical example 3 .Since the first evidence of cononsolvency was found in the 1980s, theoretical debates on its origin have continued. Currently, there are four main hypotheses, i.e., the perturbation of the water-cosolvent interaction with the presence of polymer network 4 , Competitive adsorption 5, 6 , the formation of a stoichiometric complexation between water and cosolvent 7 , and strong water-cosolvent interactions 8 . Although still widely considered, we note that the first hypothesis was tarnished when Schild et al. 9 found that similar cononsolvency phenomena happened in both macromolecular dilute solution and

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Spherically Symmetric Solvent is Sufficient to Explain the LCST Mechanism in Polymer Solutions

Cited by 4 publications

References 50 publications

Kosmotropic effect leads to LCST decrease in thermoresponsive polymer solutions

Kosmotropic effect leads to LCST decrease in thermoresponsive polymer solutions

Phase Separation of Aqueous Poly(diisopropylaminoethyl methacrylate) upon Heating

Water/Cosolvent Attraction Induced Phase Separation: A Molecular Picture of Cononsolvency

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