scholarly journals Characterization of Polymers for Fine Processing. II. Volume Phase Transitions of Poly(N-isopropylacrylamide) Gels with Temperature and Methanol/Water as Composition Discussed in Terms of Free Volume Parameters.

1996 ◽  
Vol 53 (6) ◽  
pp. 366-374 ◽  
Author(s):  
Kenji ITO ◽  
Yusuke UJIHIRA ◽  
Makoto ASANO ◽  
Takashi YAMASHITA ◽  
Kazuyuki HORIE
Keyword(s):  
Phase Transitions ◽  
Free Volume ◽  
Volume Phase

Temperature-Sensitive Nanogels PNIPAAm/DMA Prepared and Research

2012 ◽  
Vol 465 ◽  
pp. 141-145
Author(s):  
Hai Yan Wang ◽  
Qian Liao ◽  
Qiao Lan Shao ◽  
Gao Qiu ◽  
Xi Hua Lu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Synthesis And Characterization ◽  
Temperature Sensitive ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
New Class ◽  
Copolymer Gels ◽  
Temperature Controlled

There have much study about thermo-responsive nanogels,which exhibit temperature-controlled volume phase transitions.There have been few reports,however,of electrostatically neutral,thermosensitive nanogels with a high composition of hydrophilic monomer.Here,we describe the synthesis and characterization of a new class of nonionic copolymer nanogels based on N-ispropylacrylamide(NIPAM) and N,N-dimethylacrylamide(DMA),wich exhibit tunable volume phase transition temperatures.And increasing percentages of DMA in copolymer gels raises the LCST,and attenuates and broadens the volume phases transition.Through DLS, AFM and UV-Vis measurement it's size,shape and VPTTs.The character of nonionic NIPAM/DMA nanogels show it's tunable phase transitions promise to be useful for applicatipns in biotechnology and medicine.

Synthesis and characterization of ammonia-responsive polymer microgels

2015 ◽  
Vol 6 (48) ◽  
pp. 8331-8342 ◽  
Author(s):  
Yahui Peng ◽  
Xiaomei Jiang ◽  
Shoumin Chen ◽  
Qingshi Wu ◽  
Jing Shen ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Synthesis And Characterization ◽  
Sensitive Volume ◽  
Volume Phase ◽  
Highly Sensitive ◽  
Responsive Polymer

We report a polymer microgel that can undergo rapid, reversible, and highly-sensitive volume phase transitions upon varying ammonia concentrations in milieu.

scholarly journals Free-volume Characterization of Polysilanes Using Positron Annihilation Spectroscopy.

1999 ◽  
Vol 12 (5) ◽  
pp. 739-742
Author(s):  
Mutsumi Tashiro ◽  
Shu Seki ◽  
Pradeep K. Pujari ◽  
Yoshihide Honda ◽  
Seiichi Tagawa
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Annihilation Spectroscopy

scholarly journals Photoacoustic characterization of phase transitions in amorphous metal alloys

1998 ◽  
Vol 66 (2) ◽  
pp. 245-249 ◽  
Author(s):  
D.J. Orzi ◽  
G.M. Bilmes ◽  
J.O. Tocho ◽  
N. Mingolo ◽  
O.E. Martínez
Keyword(s):  
Phase Transitions ◽  
Amorphous Metal ◽  
Metal Alloys ◽  
Amorphous Metal Alloys

Characterization of Supersaturated Danazol Solutions – Impact of Polymers on Solution Properties and Phase Transitions

2016 ◽  
Vol 33 (5) ◽  
pp. 1276-1288 ◽  
Author(s):  
Matthew J. Jackson ◽  
Umesh S. Kestur ◽  
Munir A. Hussain ◽  
Lynne S. Taylor
Keyword(s):  
Phase Transitions ◽  
Solution Properties

Diffusivity of solvents in semi-crystalline polyethylene using the Vrentas-Duda free-volume theory

2018 ◽  
Vol 38 (10) ◽  
pp. 925-931 ◽  
Author(s):  
Derek R. Sturm ◽  
Kevin J. Caputo ◽  
Siyang Liu ◽  
Ronald P. Danner
Keyword(s):  
Free Volume ◽  
Weight Fraction ◽  
Amorphous Region ◽  
Model Parameters ◽  
Crystalline Region ◽  
Free Volume Theory ◽  
Melt Temperature ◽  
Tortuosity Factor ◽  
Crystalline Polyethylene

Abstract Diffusion of penetrants in polyethylene below the melt temperature is heavily dependent on the crystallinity of the polyethylene, the temperature of the experiment, and the concentration of solvent in the polymer. As the crystallinity of the polyethylene increases, there is an increase in the path that the solvent must travel as the solvent cannot penetrate the tightly packed chains in the crystalline domain. This effect is typically accounted for by a tortuosity factor. In this work, a simple and effective characterization of the tortuosity factor based simply on the crystal weight fraction has been developed. Data have been collected for six polyethylenes having densities ranging from 0.912 to 0.961 g/cm3 and for three solvents – isopentane, cyclohexane, and 1-hexene. Diffusivity predictions have been obtained using the free-volume theory of Vrentas and Duda in conjunction with the new tortuosity factor. The polyethylenes had crystallinities varying from 40% to 82% effecting an approximately 60% change in the diffusivity. The decrease resulting from ignoring the crystallinity altogether was in some cases essentially a factor of 5. The error in the predicted diffusivities over all the systems was 25%. For cyclohexane, it is shown that the same model parameters characterize data below the melt temperature (in the semi-crystalline region) as well as above the melt temperature (in the amorphous region).

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.

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