Critical fluctuations and static inhomogeneities in polymer gel volume phase transitions

2015 ◽  
Vol 53 (16) ◽  
pp. 1112-1122 ◽  
Author(s):  
Axel Habicht ◽  
Willi Schmolke ◽  
Günter Goerigk ◽  
Frank Lange ◽  
Kay Saalwächter ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Polymer Gel ◽  
Critical Fluctuations ◽  
Volume Phase

Directed Motion and Cargo Transport Through Propagation of Polymer-Gel Volume Phase Transitions

2005 ◽  
Vol 17 (15) ◽  
pp. 1869-1873 ◽  
Author(s):  
L. Yeghiazarian ◽  
S. Mahajan ◽  
C. Montemagno ◽  
C. Cohen ◽  
U. Wiesner
Keyword(s):  
Phase Transitions ◽  
Polymer Gel ◽  
Directed Motion ◽  
Volume Phase ◽  
Cargo Transport

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.

Discontinuous Binding of Surfactants to a Polymer Gel Resulting from a Volume Phase Transition

1999 ◽  
Vol 32 (25) ◽  
pp. 8589-8594 ◽  
Author(s):  
Yasuyuki Murase ◽  
Tomohiro Onda ◽  
Kaoru Tsujii ◽  
Toyoichi Tanaka
Keyword(s):  
Phase Transition ◽  
Volume Phase Transition ◽  
Polymer Gel ◽  
Volume Phase

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

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.

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