Field-Theoretic Simulation Method to Study the Liquid-Liquid Phase Separation of Polymers

Saeed Najafi; James McCarty; Kris T Delaney; Glenn H Fredrickson; Joan-Emma Shea

doi:10.1007/978-1-0716-2663-4_2

Field-Theoretic Simulation Method to Study the Liquid-Liquid Phase Separation of Polymers

Methods Mol Biol. 2023:2563:37-49. doi: 10.1007/978-1-0716-2663-4_2.

Authors

Saeed Najafi^{1

2}, James McCarty³, Kris T Delaney², Glenn H Fredrickson^{2

4}, Joan-Emma Shea^{5

6}

Affiliations

¹ Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA.
² Materials Research Laboratory, University of California, Santa Barbara, CA, USA.
³ Department of Chemistry, Western Washington University, Bellingham, WA, USA.
⁴ Department of Chemical Engineering, University of California, Santa Barbara, CA, USA.
⁵ Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA. shea@ucsb.edu.
⁶ Department of Physics, University of California Santa Barbara, Santa Barbara, CA, USA. shea@ucsb.edu.

PMID: 36227467
DOI: 10.1007/978-1-0716-2663-4_2

Abstract

Liquid-liquid phase separation (LLPS) is a process that results in the formation of a polymer-rich liquid phase coexisting with a polymer-depleted liquid phase. LLPS plays a critical role in the cell through the formation of membrane-less organelles, but it also has a number of biotechnical and biomedical applications such as drug confinement and its targeted delivery. In this chapter, we present a computational efficient methodology that uses field-theoretic simulations (FTS) with complex Langevin (CL) sampling to characterize polymer phase behavior and delineate the LLPS phase boundaries. This approach is a powerful complement to analytical and explicit-particle simulations, and it can serve to inform experimental LLPS studies. The strength of the method lies in its ability to properly sample a large ensemble of polymers in a saturated solution while including the effect of composition fluctuations on LLPS. We describe the approaches that can be used to accurately construct phase diagrams of a variety of molecularly designed polymers and illustrate the method by generating an approximation-free phase diagram for a classical symmetric diblock polyampholyte.

Keywords: Complex Langevin; Field-theoretic simulation; LLPS; Polymer.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, N.I.H., Extramural

MeSH terms

Chemical Phenomena
Computer Simulation
Organelles*
Polymers*

Substances

Polymers