The mechanism of relaxation of dipole polarization and structure formation below the temperature of phase separation of a polymer solution

1976 ◽  
Vol 18 (2) ◽  
pp. 334-340 ◽  
Author(s):  
L.L. Burshtein ◽  
V.P. Malinovskaya
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Structure Formation ◽  
Dipole Polarization

Solidification characteristics of polymer solution during polyvinylidene fluoride membrane preparation by nonsolvent-induced phase separation

2013 ◽  
Vol 438 ◽  
pp. 77-82 ◽  
Author(s):  
Toru Ishigami ◽  
Keisuke Nakatsuka ◽  
Yoshikage Ohmukai ◽  
Eiji Kamio ◽  
Tatsuo Maruyama ◽  
...  
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Polyvinylidene Fluoride ◽  
Membrane Preparation

scholarly journals Prebiotically-relevant low polyion multivalency can improve functionality of membraneless compartments

2020 ◽  
Author(s):  
Fatma Pir Cakmak ◽  
Saehyun Choi ◽  
McCauley O. Meyer ◽  
Philip C. Bevilacqua ◽  
Christine D. Keating
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Structure Formation ◽  
Rna Structure ◽  
Salt Resistance ◽  
Origins Of Life ◽  
Complex Coacervation ◽  
The Impact ◽  
Local Ph

AbstractMultivalent polyions can undergo complex coacervation, producing membraneless compartments that accumulate ribozymes and enhance catalysis, and offering a mechanism for functional prebiotic compartmentalization in the origins of life. Here, we evaluated the impact of low, prebiotically-relevant polyion multivalency in coacervate performance as functional compartments. As model polyions, we used positively and negatively charged homopeptides with one to 100 residues, and adenosine mono-, di-, and triphosphate nucleotides. Polycation/polyanion pairs were tested for coacervation, and resulting membraneless compartments were analyzed for salt resistance, ability to provide a distinct internal microenvironment (apparent local pH, RNA partitioning), and effect on RNA structure formation. We find that coacervates formed by phase separation of the relatively shorter polyions more effectively generated distinct pH microenvironments, accumulated RNA, and preserved duplexes. Hence, reduced multivalency polyions are not only viable as functional compartments for prebiotic chemistries, but they can offer advantages over higher molecular weight analogues.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

scholarly journals Prebiotically-relevant low polyion multivalency can improve functionality of membraneless compartments

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Fatma Pir Cakmak ◽  
Saehyun Choi ◽  
McCauley O. Meyer ◽  
Philip C. Bevilacqua ◽  
Christine D. Keating
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Structure Formation ◽  
Rna Structure ◽  
Functional Performance ◽  
Salt Resistance ◽  
Origins Of Life ◽  
Complex Coacervation ◽  
The Impact ◽  
Local Ph

AbstractMultivalent polyions can undergo complex coacervation, producing membraneless compartments that accumulate ribozymes and enhance catalysis, and offering a mechanism for functional prebiotic compartmentalization in the origins of life. Here, we evaluate the impact of lower, more prebiotically-relevant, polyion multivalency on the functional performance of coacervates as compartments. Positively and negatively charged homopeptides with 1–100 residues and adenosine mono-, di-, and triphosphate nucleotides are used as model polyions. Polycation/polyanion pairs are tested for coacervation, and resulting membraneless compartments are analyzed for salt resistance, ability to provide a distinct internal microenvironment (apparent local pH, RNA partitioning), and effect on RNA structure formation. We find that coacervates formed by phase separation of the shorter polyions more effectively generated distinct pH microenvironments, accumulated RNA, and preserved duplexes than those formed by longer polyions. Hence, coacervates formed by reduced multivalency polyions are not only viable as functional compartments for prebiotic chemistries, they can outperform higher molecular weight analogues.

Producing PVP Nanofibers by Electrospinning in N2

2012 ◽  
Vol 560-561 ◽  
pp. 701-708 ◽  
Author(s):  
Lu Li ◽  
Jie Xu ◽  
Tao Fang ◽  
Jin Geng ◽  
Detlef Freitag ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Phase Equilibrium ◽  
Phase Separation ◽  
Phase Behavior ◽  
Polymer Solution ◽  
Aspen Plus ◽  
Good Choice ◽  
The Other ◽  
Binary Phase ◽  
Novel Method

Electrospinning combined with nonsolvent-induced phase separation is a simple and novel method to produce porous nanofibers. In the study, Poly (vinylpyrrolidone) (PVP) nanofibers were fabricated using an electrospinning approach complemented by compressed nitrogen (N). N2 was used as the nonsolvent of choice. Besides, the tun2ning of N2 pressure and temperature can impact the nanofibers’ morphologies by altering phase behavior and mass transfer. Also, the other parameters affecting electrospinning of polymer solution were discussed. The results were demonstrated by extending the technique to PVP/dichloromethane (DCM) and PVP/ethanol (EtOH) systems. And the binary phase equilibrium of solvents (dichloromethane or ethanol) and N simulated by ASPEN PLUS 2006 demonstrates that N is not a 2good choice for producing hollow or po2rous polymer nanofibers.

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