Phase behaviour of polyampholyte chains from grand canonical Monte Carlo simulations

Cheong, Daniel W.; Panagiotopoulos, Athanassios Z.

doi:10.1080/00268970500186045

Cited by 23 publications

(41 citation statements)

References 66 publications

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“…* cr 's is 0.339/0.117 = 2.90 for N = 8 and 1.215/0.143 = 8.50 for N = 16. The corresponding ratios from the explicit-chain simulation data of ref 86. are, respectively, 0.361/0.240 = 1.50 and 0.876/0.278 = 3.15.…”

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confidence: 94%

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A Lattice Model of Charge-Pattern-Dependent Polyampholyte Phase Separation

et al. 2018

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In view of recent intense experimental and theoretical interests in the biophysics of liquid-liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs), heteropolymer models with chain molecules configured as self-avoiding walks on the simple cubic lattice are constructed to study how phase behaviors depend on the sequence of monomers along the chains. To address pertinent general principles, we focus primarily on two fully charged 50-monomer sequences with significantly different charge patterns. Each monomer in our models occupies a single lattice site, and all monomers interact via a screened pairwise Coulomb potential. Phase diagrams are obtained by extensive Monte Carlo sampling performed at multiple temperatures on ensembles of 300 chains in boxes of sizes ranging from 52 × 52 × 52 to 246 × 246 × 246 to simulate a large number of different systems with the overall polymer volume fraction ϕ in each system varying from 0.001 to 0.1. Phase separation in the model systems is characterized by the emergence of a large cluster connected by intermonomer nearest-neighbor lattice contacts and by large fluctuations in local polymer density. The simulated critical temperatures, T, of phase separation for the two sequences differ significantly, whereby the sequence with a more "blocky" charge pattern exhibits a substantially higher propensity to phase separate. The trend is consistent with our sequence-specific random-phase-approximation (RPA) polymer theory, but the variation of the simulated T with a previously proposed "sequence charge decoration" pattern parameter is milder than that predicted by RPA. Ramifications of our findings for the development of analytical theory and simulation protocols of IDP LLPS are discussed.

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confidence: 94%

“…10). Green diamonds: Simulated results and predictions by salt-free RPA theory for three different N = 16 sequences in ref 86…”

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confidence: 99%

A Lattice Model of Charge-Pattern-Dependent Polyampholyte Phase Separation

et al. 2018

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“…In polyampholyte solutions electrostatic interactions between oppositely charged monomers promote phase separation [89]. The condition for phase separation depends on the chain degree of polymerization, charge sequence along the polymer backbone, strength of the electrostatic interactions and solution temperature.…”

Section: Salt Effectsmentioning

confidence: 99%

Theory and simulations of charged polymers: From solution properties to polymeric nanomaterials

Dobrynin

2008

Current Opinion in Colloid & Interface Science

262

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“…One principal advantage of polyampholytes is that their association and stabilization behavior can be easily regulated by adjusting solution pH. This leads to many potential applications 5 and considerable interest in experimental, [33][34][35][36][37][38][39][40] theoretical, 2, 28, 41-45 and simulation [46][47][48][49][50][51][52][53][54][55][56] studies of polyampholytes. The conductivity, viscosity, as well as coil size of random polyampholytes have a minimum at the isoelectric conditions where there are equal numbers of positive and negative charges on the polymer backbone.…”

Section: Introductionmentioning

confidence: 99%

“…Grand canonical Monte Carlo simulations have also been performed to study the phase diagram of diblock polyampholyte solutions. 51 A charge-symmetric diblock polyampholyte chain with equally charged positive and negative blocks collapses into a globule, while a charge-asymmetric block polyampholyte has a tadpole shape with a globular head and a polyelectrolyte tail. 44 The association of block polyampholytes is driven by the charge density fluctuationinduced attractive interactions between oppositely charged blocks.…”

Section: Introductionmentioning

confidence: 99%