scholarly journals Phase Transition Behaviors of Hydroxypropyl Methylcellulose Induced By Small Molecular Weak Acids

2021 ◽  
Author(s):  
Zhifei Xu ◽  
Qixuan Zhao ◽  
Di Zhao
Keyword(s):  
Phase Transition ◽  
Hydrogen Bonding ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Effect ◽  
Hydroxypropyl Methylcellulose ◽  
Weak Acids ◽  
Bonding Effect ◽  
Change Material ◽  
Hydrogen Bonding Effect

Abstract In this paper, phase change material hydroxypropyl methylcellulose (HPMC) was chosen to investigate the influence of small molecular weak acids on its phase transition temperature. The results showed that all of the chosen small molecular weak acids such as acrylic acid (AA), methacrylic acid (MAA), DL-lactic acid (LA), citric acid (CA) and acetic acid (AAc) can trigger the decrease of phase transition temperature of HPMC at different pH. With the increase of pH, AA, LA, CA and AAc can further lower the phase transition temperature, on the contrary, the phase transition temperature of HPMC increased with MAA. The change range of LCST was largest around pKa compared with other pH values because triggering effect changed gradually from hydrogen bonding effect to salt effect upon the increase of pH. Besides, phase transition temperature can also be reduced by the increase of acid concentration. This is attributed to smaller distance between molecules caused by higher concentration leading to stronger hydrogen bonding effect or salt effect. This paper provided a new perspective to modulate the LCST of phase change material by small molecular weak acids at different pH.

Ultrahigh phase transition temperature in a metal–halide perovskite-type material containing unprecedented hydrogen bonding interactions

2019 ◽  
Vol 48 (19) ◽  
pp. 6621-6626 ◽  
Author(s):  
Xiu-Ni Hua ◽  
Ji-Xing Gao ◽  
Xiao-Gang Chen ◽  
Peng-Fei Li ◽  
Guang-Quan Mei ◽  
...  
Keyword(s):  
Phase Transition ◽  
Hydrogen Bonding ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
High Temperatures ◽  
Type Material ◽  
Hydrogen Bonding Interactions ◽  
Metal Halide Perovskite ◽  
Halide Perovskite ◽  
Perovskite Type

An ABX3 perovskite-type compound (N,N-dimethylethanolammonium)CdCl3 with hydrogen bonding interactions between organic ammonium cations undergoes a phase transition at super-high temperatures.

The influence of l-amino acid molecular structure on the phase transition temperature of hydroxypropyl methylcellulose

2006 ◽  
Vol 65 (1) ◽  
pp. 22-27 ◽  
Author(s):  
J. Craig Richardson ◽  
Craig S. Foster ◽  
Steve W. Doughty ◽  
Janet S. Burton ◽  
Ross J. MacRae ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Phase Transition ◽  
Transition Temperature ◽  
Amino Acid ◽  
Phase Transition Temperature ◽  
Hydroxypropyl Methylcellulose

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

scholarly journals Study of physical properties of a ferrimagnetic spinel Cu1.5Mn1.5O4: spin dynamics, magnetocaloric effect and critical behavior

RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25664-25676
Author(s):  
Abir Hadded ◽  
Jalel Massoudi ◽  
Sirine Gharbi ◽  
Essebti Dhahri ◽  
A. Tozri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Physical Properties ◽  
Magnetocaloric Effect ◽  
Phase Transition Temperature ◽  
Magnetic Phase Transition ◽  
Critical Behavior ◽  
Magnetic Phase ◽  
Spin Dynamics ◽  
Critical Behaviour

The present work reports a detailed study of the spin dynamics, magnetocaloric effect and critical behaviour near the magnetic phase transition temperature, of a ferrimagnetic spinel Cu1.5Mn1.5O4.

scholarly journals Modulating the phase transition temperature of giant magnetocaloric thin films by ion irradiation

2017 ◽  
Vol 1 (6) ◽  
Author(s):  
S. Cervera ◽  
M. Trassinelli ◽  
M. Marangolo ◽  
C. Carrétéro ◽  
V. Garcia ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Ion Irradiation
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