Synthesis of Nanogels of Poly Methyacrylic Acid Using Methyl Cellulose as a Template

2014 ◽  
Vol 787 ◽  
pp. 401-406
Author(s):  
Jun Li Zhang ◽  
Peng Wang ◽  
Dong An ◽  
Xue Ting Li ◽  
Qian Wu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Methacrylic Acid ◽  
Aqueous Media ◽  
Polymer System ◽  
Methyl Cellulose ◽  
Solution Temperature ◽  
Lower Phase ◽  
Lower Temperature

In recent decades, thermo sensitive polymer system has been intensively studied due to significant importance in fundamental studies and various applications. Methyl cellulose (MC) is a thermo sensitive natural polymer, having a phase transition temperature or a lower critical solution temperature of about 65 °C. When methacrylic acid (MAA) was added to the MC solution, the phase transition of MC occurred at a lower temperature less than 65°C, and a higher concentration of MAA leds to a lower phase transition temperature of MC. Based on the phase transition of MC solution triggered by MAA, the surfactant-free poly (methacrylic acid) nanogels were synthesized by using methyl cellulose as a template in an aqueous media. The resulting PMAA nanogels characterized by using dynamic light scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR). The nanogels of poly methyacrylic acid (PMAA) were affected by the concentration of both MC and MAA. A higher concentration of MAA led to a higher polymerization rate, and the higher concentration of MC resulted in the formation of the samller size of PMAA nanogels.

scholarly journals Influence of dimensionality on phase transition in VO2 nanocrystals

2013 ◽  
Vol 45 (3) ◽  
pp. 305-311 ◽  
Author(s):  
V.A. Blagojevic ◽  
N. Obradovic ◽  
N. Cvjeticanin ◽  
D.M. Minic
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Transition Temperature ◽  
Apparent Activation Energy ◽  
Phase Transition Temperature ◽  
Bulk Material ◽  
Two Dimensional ◽  
Lower Phase ◽  
One Dimensional ◽  
Simultaneous Movement

Hydrothermally synthesized one-dimensional and two-dimensional nanocrystals of VO2 undergo phase transition around 65?C, where temperature and mechanism of phase transition are dependent on dimensionality of nanocrystals. Both nanocrystalline samples exhibit depression of phase transition temperature compared to the bulk material, the magnitude of which depends on the dimensionality of the nanocrystal. One-dimensional nanoribbons exhibit lower phase transition temperature and higher values of apparent activation energy than two-dimensional nanosheets. The phase transition exhibits as a complex process with somewhat lower value of enthalpy than the phase transition in the bulk, probably due to higher proportion of surface atoms in the nanocrystals. High values of apparent activation energy indicate that individual steps of the phase transition involve simultaneous movement of large groups of atoms, as expected for single-domain nanocrystalline materials.

Lower phase transition temperature of solid hydrogen sulphide

1972 ◽  
Vol 22 (7) ◽  
pp. 617-620
Author(s):  
A. S. Farghaly
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Hydrogen Sulphide ◽  
Solid Hydrogen ◽  
Lower Phase

FePt nanoparticle formation with lower phase transition temperature by single shot plasma focus ion irradiation

2008 ◽  
Vol 41 (13) ◽  
pp. 135213 ◽  
Author(s):  
J J Lin ◽  
M V Roshan ◽  
Z Y Pan ◽  
R Verma ◽  
P Lee ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Plasma Focus ◽  
Ion Irradiation ◽  
Single Shot ◽  
Lower Phase ◽  
Nanoparticle Formation ◽  
Fept Nanoparticle

NANOSTRUCTURE AND DROPPING PHASE TRANSITION TEMPERATURE IN VANADIUM DIOXIDE THIN FILMS

2005 ◽  
Vol 04 (01) ◽  
pp. 99-106 ◽  
Author(s):  
XINJIAN YI ◽  
YI LI ◽  
SIHAI CHEN ◽  
SHUANGBAO WANG ◽  
JIANJUN LAI ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Vanadium Dioxide ◽  
Infrared Imaging ◽  
Film Structure ◽  
Smart Window ◽  
Device Applications ◽  
Lower Temperature ◽  
Uncooled Infrared Imaging

A conventional microstructure of vanadium dioxide film with grain size of 1–2 μm exhibits a phase transition from a lower-temperature semiconductor phase to a higher-temperature metal one with a phase transition temperature of 68°C and with resistivity changes two to three orders of magnitude. Here, we report a nonconventional nanopolycrystalline thin film structure of vanadium dioxide with an average grain of 8 nm and with a phase transition temperature of about 35°C, indicating more promising device applications such as smart window coatings for solar energy, uncooled infrared imaging technology, optical and electronic switching devices, etc.

scholarly journals Fluctuation In the Phase Transition Temperature of Poly (NIPAAm-co-HEMA-co-DMAMVA)-Post-guanine Affected by Hydrophilic/hydrophobic Interaction: Fabrication and Characterizations

2021 ◽  
Author(s):  
Momen Abdelaty
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Polymer Solution ◽  
Phase Transition Temperature ◽  
Click Reaction ◽  
Aldehyde Group ◽  
Solution Temperature ◽  
Hydroxyethyl Methacrylate ◽  
Dual Responsive ◽  
Vis Spectroscopy

Abstract The phase separation and transition temperature of poly (N-isopropylacrylamide) have been developed by the terpolymerization with new pH-responsive monomer and highly hydrophilic 2-Hydroxyethyl methacrylate. The new monomer based on vanillin is called 2-((dimethylamino)methyl)-4-formyl-6-methoxyphenyl acrylate (DMAMVA), and is investigated by chemical methods (1H, 13C NMR, FTIR, and mass spectroscopy). Terpolymers of dual-responsive thermo-pH with functional groups were fabricated via free radical polymerization of N-isopropylacrylamide (NIPAAm), 10 mol% 2-Hydroxyethyl methacrylate (HEMA), and 5, 10, and 20 mol% DMAMVA. A selected terpolymer was used for post-polymerization with guanine via click reaction and the formation of an imine between the aldehyde group of DMAMVA and the amine group of guanine. All terpolymer and post-terpolymer are chemically evaluated. The physical properties have been implemented by GPC (molecular weight and dispersity), DSC (glass transition temperature Tg), TGA (steps of degradation), and SEM (morphological features). The fluctuations in phase transition temperature Tc or the lower critical solution temperature LCST of the polymer solution in different pH solutions have been performed by two methods, first, the turbidity test by UV-Vis-spectroscopy, second, by micro-DSC for aqueous polymer solution. This work will be extended for more applications in bio-separation technology.

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.

Molecular Ordering of a Nematogen at Phase Transition Temperature - A Theoretical Study

2002 ◽  
Vol 75 (4-5) ◽  
pp. 413-421
Author(s):  
Durga Prasad Ojha ◽  
Devesh Kumar ◽  
V.G.K.M. Pisipati
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Theoretical Study ◽  
Molecular Ordering
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