Molecular insights on poly(<i>N</i>-isopropylacrylamide) coil-to-globule transition induced by pressure

Tavagnacco, Letizia; Chiessi, Ester; Zaccarelli, Emanuela

doi:10.1039/d0cp06452a

Cited by 14 publications

(34 citation statements)

References 65 publications

(86 reference statements)

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“…Globular states were assigned to conformations with an average radius of gyration smaller than 1.2 nm. This cutoff value, already introduced in previous studies, 63 corresponds to the value of R G at the inflection point obtained by fitting using a sigmoidal function the temperature evolution of the average radius of gyration at atmospheric pressure ( Figure 1 A).…”

Section: Methodsmentioning

confidence: 87%

“…Data are calculated at 0.1 MPa for TIP4P/Ice (green circles) and TIP4P/2005 (violet triangles). Data for TIP4P/Ice are reproduced from ref ( 63 ).…”

Section: Results and Discussionmentioning

confidence: 99%

“…The transition temperature values, equal to 298.5 ± 1.5 and 288.5 ± 1.0 K for TIP4P/Ice and TIP4P/2005, respectively, are identified by vertical bands including error bars. Data for TIP4P/Ice are reproduced from ref ( 63 ).…”

Section: Methodsmentioning

confidence: 99%

“… 42 , 48 , 49 , 55 , 56 , 62 Recently, the OPLS-AA force field, with some revisions aimed at increasing PNIPAM–water affinity, has been the one more frequently adopted. 36 , 40 − 46 , 48 − 52 , 54 , 55 , 57 − 63 Interestingly, there is an even greater heterogeneity for the water model selected to simulate this polymer in aqueous environments, including SPC, 35 SPC/E, 43 , 45 , 48 , 49 , 53 − 55 , 61 PCFF, 38 TIP3P, 37 , 39 , 56 TIP4P, 46 TIP4P/2005, 36 , 40 − 42 , 44 , 57 , 58 , 62 and TIP4P/Ice 50 − 52 , 59 , 60 , 63 water models. With this background and with the aim of extending atomistic simulation methods to other PNIPAM-based systems, it would thus be valuable for the community to identify the best protocol in terms of both PNIPAM and water parametrization.…”

Section: Introductionmentioning

confidence: 99%

“…Recent MD simulations provided insights into the behavior of PNIPAM systems in aqueous media, 36 , 40 , 41 , 51 , 57 , 58 , 60 extending the range of temperatures and pressures to unexplored regions. 50 , 52 , 59 , 63 These studies have consistently used the same polymer force field, namely, the OPLS-AA 64 with the modifications of Siu et al, 65 but they either employed TIP4P/2005 66 or TIP4P/Ice 67 for water, depending on the physical conditions investigated. Both water models, proposed by the Vega’s group in 2005, are very effective in reproducing several water properties, each one with its own peculiarities: on one hand, the TIP4P/2005 model captures very well the dependence of the isothermal compressibility on pressure at 298 K as well as the slope of the P–T coexistence line; on the other hand, the TIP4P/Ice model allows for an excellent prediction of melting temperature.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Solution Behavior of Poly(N-isopropylacrylamide): A Comparison between Water Models

2022

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Water is known to play a fundamental role in determining the structure and functionality of macromolecules. The same crucial contribution is also found in the in silico description of polymer aqueous solutions. In this work, we exploit the widely investigated synthetic polymer poly( N -isopropylacrylamide) (PNIPAM) to understand the effect of the adopted water model on its solution behavior and to refine the computational setup. By means of atomistic molecular dynamics simulations, we perform a comparative study of PNIPAM aqueous solution using two advanced water models: TIP4P/2005 and TIP4P/Ice. The conformation and hydration features of an atactic 30-mer at infinite dilution are probed at a range of temperature and pressure suitable to detect the coil-to-globule transition and to map the P–T phase diagram. Although both water models can reproduce the temperature-induced coil-to-globule transition at atmospheric pressure and the polymer hydration enhancement that occurs with increasing pressure, the PNIPAM–TIP4P/Ice solution shows better agreement with experimental findings. This result can be attributed to a stronger interaction of TIP4P/Ice water with both hydrophilic and hydrophobic groups of PNIPAM, as well as to a less favorable contribution of the solvent entropy to the coil-to-globule transition.

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Section: Methodsmentioning

confidence: 87%

“…Data are calculated at 0.1 MPa for TIP4P/Ice (green circles) and TIP4P/2005 (violet triangles). Data for TIP4P/Ice are reproduced from ref ( 63 ).…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling Solution Behavior of Poly(N-isopropylacrylamide): A Comparison between Water Models

2022

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Cononsolvency of the responsive polymer poly(N-isopropylacrylamide) in water/methanol mixtures: a dynamic light scattering study of the effect of pressure on the collective dynamics

et al. 2022

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The collective dynamics of 25 wt% poly(N-isopropylacrylamide) (PNIPAM) solutions in water or an 80:20 v/v water/methanol mixture are investigated in the one-phase region in dependence on pressure and temperature using dynamic light scattering. Throughout, two dynamic modes are observed, the fast one corresponding to the relaxation of the chain segments within the polymer blobs and the slow one to the relaxation of the blobs. A pressure scan in the one-phase region on an aqueous solution at 34.0 °C, i.e., slightly below the maximum of the coexistence line, reveals that the dynamic correlation length of the fast mode increases when the left and the right branch of the coexistence line are approached. Thus, the chains are rather swollen far away from the coexistence line, but contracted near the phase transition. Temperature scans of solutions in neat H2O or in H2O/CD3OD at 0.1, 130, and 200 MPa reveal that the dynamic correlation length of the fast mode shows critical behavior. However, the critical exponents are significantly larger than the value predicted by mean-field theory for the static correlation length, ν = 0.5, and the exponent is significantly larger for the solution in the H2O/CD3OD mixture than in neat H2O.

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One-step grafting reaction of thermoresponsive polymer brushes over silica nanoparticles

Peña

Du²,

Xing³

2022

Colloid Polym Sci

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Molecular insights on poly(N-isopropylacrylamide) coil-to-globule transition induced by pressure

Abstract: By using extensive all-atom molecular dynamics simulations of an atactic linear polymer chain, we provide microscopic insights into Poly(N-isopropylacrylamide) (PNIPAM) coil-to-globule transition addressing the roles played by both temperature and...

Cited by 14 publications

References 65 publications

Modeling Solution Behavior of Poly(N-isopropylacrylamide): A Comparison between Water Models

Modeling Solution Behavior of Poly(N-isopropylacrylamide): A Comparison between Water Models

Cononsolvency of the responsive polymer poly(N-isopropylacrylamide) in water/methanol mixtures: a dynamic light scattering study of the effect of pressure on the collective dynamics

One-step grafting reaction of thermoresponsive polymer brushes over silica nanoparticles

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