scholarly journals Salt-Induced Swelling and Volume Phase Transition of Polyelectrolyte Gels

2017 ◽  
Vol 84 (5) ◽  
Author(s):  
Yalin Yu ◽  
Chad M. Landis ◽  
Rui Huang
Keyword(s):  
Phase Transitions ◽  
Salt Concentration ◽  
Volume Fraction ◽  
External Solution ◽  
Quantitative Agreement ◽  
Continuous Transition ◽  
Volume Phase ◽  
Polyelectrolyte Gels ◽  
Monovalent Ions ◽  
Polymer Solvent

A theoretical model of polyelectrolyte gels is presented to study continuous and discontinuous volume phase transitions induced by changing salt concentration in the external solution. Phase diagrams are constructed in terms of the polymer–solvent interaction parameters, external salt concentration, and concentration of fixed charges. Comparisons with previous experiments for an ionized acrylamide gel in mixed water–acetone solvents are made with good quantitative agreement for a monovalent salt (NaCl) but fair qualitative agreement for a divalent salt (MgCl2), using a simple set of parameters for both cases. The effective polymer–solvent interactions vary with the volume fraction of acetone in the mixed solvent, leading to either continuous or discontinuous volume transitions. The presence of divalent ions (Mg2+) in addition to monovalent ions in the external solution reduces the critical salt concentration for the discontinuous transition by several orders of magnitude. Moreover, a secondary continuous transition is predicted between two highly swollen states for the case of a divalent salt. The present model may be further extended to study volume phase transitions of polyelectrolyte gels in response to other stimuli such as temperature, pH and electrical field.

Volume-phase transitions of cationic polyelectrolyte gels

Polymer ◽  
1992 ◽  
Vol 33 (23) ◽  
pp. 5040-5043 ◽  
Author(s):  
Shinichi Kudo ◽  
Norio Kosaka ◽  
Mikio Konno ◽  
Shozaburo Saito
Keyword(s):  
Phase Transitions ◽  
Cationic Polyelectrolyte ◽  
Volume Phase ◽  
Polyelectrolyte Gels

scholarly journals Wave onset in central gray matter - its intrinsic optical signal and phase transitions in extracellular polymers

2001 ◽  
Vol 73 (3) ◽  
pp. 351-364 ◽  
Author(s):  
VERA M. FERNANDES-DE-LIMA ◽  
JOÃO E. KOGLER ◽  
JOCELYN BENNATON ◽  
WOLFGANG HANKE
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Gray Matter ◽  
Action Potentials ◽  
Optical Signal ◽  
Excitable Media ◽  
Extracellular Polymers ◽  
Axon Membrane ◽  
Intrinsic Optical Signal ◽  
Volume Phase

The brain is an excitable media in which excitation waves propagate at several scales of time and space. ''One-dimensional'' action potentials (millisecond scale) along the axon membrane, and spreading depression waves (seconds to minutes) at the three dimensions of the gray matter neuropil (complex of interacting membranes) are examples of excitation waves. In the retina, excitation waves have a prominent intrinsic optical signal (IOS). This optical signal is created by light scatter and has different components at the red and blue end of the spectrum. We could observe the wave onset in the retina, and measure the optical changes at the critical transition from quiescence to propagating wave. The results demonstrated the presence of fluctuations preceding propagation and suggested a phase transition. We have interpreted these results based on an extrapolation from Tasaki's experiments with action potentials and volume phase transitions of polymers. Thus, the scatter of red light appeared to be a volume phase transition in the extracellular matrix that was caused by the interactions between the cellular membrane cell coat and the extracellular sugar and protein complexes. If this hypothesis were correct, then forcing extracellular current flow should create a similar signal in another tissue, provided that this tissue was also transparent to light and with a similarly narrow extracellular space. This control tissue exists and it is the crystalline lens. We performed the experiments and confirmed the optical changes. Phase transitions in the extracellular polymers could be an important part of the long-range correlations found during wave propagation in central nervous tissue.

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

Temperature-Jump Investigations of the Kinetics of Hydrogel Nanoparticle Volume Phase Transitions

2001 ◽  
Vol 123 (45) ◽  
pp. 11284-11289 ◽  
Author(s):  
Jianping Wang ◽  
Daoji Gan ◽  
L. Andrew Lyon ◽  
Mostafa A. El-Sayed
Keyword(s):  
Phase Transitions ◽  
Temperature Jump ◽  
Volume Phase ◽  
Kinetics Of

Volume phase transition of polyelectrolyte gels in dimethyl sulfoxide/ tetrahydrofuran mixtures

Polymer ◽  
1996 ◽  
Vol 37 (26) ◽  
pp. 5947-5949 ◽  
Author(s):  
Xinxing Liu ◽  
Zhen Tong ◽  
Xianwu Cao ◽  
Ou Hu
Keyword(s):  
Phase Transition ◽  
Dimethyl Sulfoxide ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Polyelectrolyte Gels

scholarly journals Swelling of ionic microgel particles in the presence of excluded-volume interactions: a density functional approach

2016 ◽  
Vol 18 (7) ◽  
pp. 5372-5385 ◽  
Author(s):  
Arturo Moncho-Jordá ◽  
Joachim Dzubiella
Keyword(s):  
Density Functional Theory ◽  
Salt Concentration ◽  
Density Functional ◽  
Functional Approach ◽  
Excluded Volume ◽  
Local Concentration ◽  
Functional Theory ◽  
Monovalent Ions ◽  
Microgel Particles ◽  
Theory Framework

In this work a new density functional theory framework is developed to predict the salt-concentration dependent swelling state of charged microgels and the local concentration of monovalent ions inside and outside the microgel.

Sign in / Sign up

Export Citation Format

Share Document