Authors:M. Pappalardo, D. Milardi, D. Grasso, and C. La Rosa
Summary DPPC dispersions containing DPPE with attached PEG of molecular masses 350, 2000 and 5000 were investigated by DSC in order to determine their phase behaviour and potential use as drug delivery systems. In comparison with previously obtained ESR data, DSC provided a definition of the lipid composition and temperature at which the vesicles are in a liquid crystalline phase. For DPPC DPPE-PEG 350 the composition range is at molar fractions 0<&PEG350<0.5.For DPPC DPPE-PEG 2000 the range of applicability is 0<&PEG2000<0.07 and for DPPC/DPPE-PEG 5000 system it is 0<&PEG5000<0.05.
The phase behaviour and phase stability of lipids are of importance in an understanding of the biological functions of cell membranes. Among a variety of physical techniques employed to study the phase behaviour and structural properties of polar lipids, differential scanning calorimetry and X-ray diffraction have proved to be successful and are the most frequently used methods. Applications involving a combination of the two techniques, particularly when synchrotron radiation is used as the light source of X-ray diffraction, are reviewed in this article.
The present report deals with some results on phase behavior, miscibility and phase separation for several polymer blends casting from solutions. These blends are grouped as the amorphous polymer blends, blends containing a crystalline polymer or two crystalline polymers. The blends of PMMA/PVAc were miscible and underwent phase separation at elevated temperature, exhibited LCST behavior. The benzoylated PPO has both UCST and LCST nature. For the systems composed of crystalline polymer poly(ethylene oxide) and amorphous polyurethane, of two crystalline polymers poly(-caprolactone) and poly[3,3,-bis-(chloromethyl) oxetane], appear a single Tg, indicating these blends are miscible. The interaction parameter B's were determined to be –14 J cm–3, –15 J cm–3 respectively. Phase separation of phenolphthalein poly(ether ether sulfone)/PEO blends were discussed in terms of thermal properties, such as their melting and crystallization behavior.
Authors:Ya-Ting Hsieh, Nai-Tzu Kuo, and Eamor M. Woo
Thermal transitions and phasebehavior in polymer blends can be temperature dependent, as revealed in common upper critical solution temperature (UCST) or lower critical solution temperature (LCST) phenomena. UCST
Authors:X. Z. Lan, H. R. Pei, X. Yan, and W. B. Liu
, organic solvents, and ionic liquid. However, phasebehavior of binary mixture in confined state has rarely been investigated. Czwartos et al. [ 15 ] have studied solid–liquid (s–l) phase diagram of C 6 H 5 Br–CCl 4 confined in CPGs with average pore
Authors:Nadia Mayoufi, Didier Dalmazzone, Walter Fürst, Leila Elghoul, Adel Seguatni, Anthony Delahaye, and Laurence Fournaison
latent heat of phase change. In this study, this technique was used to investigate the CO 2 pressure effect on the phasebehaviour and the enthalpy changes in the system CO 2 + TBMAC + H 2 O. In addition, IR spectrometry experiments were performed for
[ 7 ]. Archaeal tetraether lipids are an excellent source for the formation of mixed liposomes with enhanced tightness against solute leakage [ 8 ]. In this study, we investigated the phasebehaviours and permeabilities of mixed C 25,25 –DPPC liposomes
stigmasterol (shown in Fig. 1 ) have been used to prepare liposomes. We have investigated the thermotropic phasebehavior of stigmasterol/DPPC liposomes and constructed the binary phase diagram of this binary system employing differential scanning calorimetry
Authors:P. Schulz, J. Rodríguez, F. Soltero-Martínez, J. Puig, and Z. Proverbio
The phase behaviour of the twin-tailed surfactant dioctadecyldimethylammonium bromide with water was studied by DSC, FT-IR,
X-ray and polarizing microscope. The phase diagram of DODAB-water system is very similar to that of DODAC-water. The dihydrate
is in equilibrium with isotropic solution below 55°C. Above this temperature there is a lamellar liquid crystalline region,
in equilibrium with isotropic liquid and solid crystals of DODAB·2H2O, up to 69°C. From 69 to 86°C, the lamellar mesophase is in equilibrium with ‘waxy’ anhydrous DODAB. From 86 to 116°C and
very high DODAB content, there is a very narrow region of existence of inverse hexagonal mesophase, in equilibrium via a narrow
biphase region with lamellar mesophase. AtT > 116°C an isotropic liquid appears. There seems to exist two different lamellar mesophases, one of them between 10 and 40
wt.% DODAB and the other between 60 and about 97 wt.% DODAB, with a biphase zone between them.
Authors:Luis Alberto Alcazar-Vara and Eduardo Buenrostro-Gonzalez
mechanism of high molecular weight n -paraffins in the presence of solvents and asphaltenes of different chemical nature where the liquid–solid phasebehavior and crystallinity are studied by means of Differential Scanning Calorimetry (DSC) and FT