Authors:S. Verheyen, N. Blaton, R. Kinget, and G. Van den Mooter
Differential scanning calorimetry (DSC) data showed that the crystallinity of poly(ethylene glycol) 6000 in solid dispersions
containing and diazepam or temazepam only slightly increased upon aging and that the twice folded modification of the polymer
unfolded into the once folded modification during aging, while the once folded modification did not unfold. This unfolding
was found to be time and temperature dependent. X-ray powder diffraction data revealed that the drug crystallinity in the
solid dispersions slightly increased upon aging. The dissolution profiles of aged and non-aged solid dispersions were comparable.
It was concluded that polymer unfolding did not have an impact on the pharmaceutical performance of the investigated dispersions.
Authors:C. G. Mothé, A. D. Azevedo, W. S. Drumond, S. H. Wang, and R. D. Sinisterra
excellent mechanical properties, they might be widely used in pharmaceutical and other medical applications. Poly(ethyleneglycol) (PEG) presents remarkable biological and physico-chemical properties, including hydrophilicity, solubility in water and organic
Authors:F. Attanasio, G. Rialdi, R. Swierzewski, and W. Zielenkiewicz
The physico-chemical properties
of poly(ethylene) glycol solutions in water have been studied with use of
pressure perturbation calorimetry. The three PEGs of average molecular mass
(Mr) 6000, 10000,
20000 were used. The concentration of polymers was changed in the range 0–30%
mass per volume (w/v%).
On the basic of VP-DSC measurements with use of PPC technique the dependencies
of thermal expansion coefficient (α) and excess specific heat capacity
(Cp,exc) on temperature
were determinated for PEG–water solutions.
Effects of nano-metal powders (aluminum and nickel) addition on the thermooxidative degradation of binder PEG in air atmosphere
from 20 to 350°C were studied by TG/DTA and in-situ FTIR. TG/DTA results showed that the addition of nano-Al slowed down the
degradation process of PEG in the early period but accelerated the process in the late period; the addition of nano-Ni made
the PEG degradation process begin as soon as melted. The in-situ FTIR results showed that nano-Ni promoted the thermooxidative
degradation of PEG in air, and made the degradation process of PEG complete much earlier.
Authors:S. Verheyen, N. Blaton, R. Kinget, and G. Van den Mooter
The effect of grinding on the physical properties and pharmaceutical performance of solid dispersions made of poly(ethylene)
glycol 6000 (PEG6000) and temazepam or diazepam was studied using differential scanning calorimetry (DSC), X-ray powder diffraction
and dissolution experiments. DSC-analysis of flash-cooled dispersions revealed that amorphous PEG present immediately after
grinding crystallised upon aging mainly into the twice folded modification and to a small extent into the extended form. DSC-analysis
of dispersions kept in the slab form for 1 month and subsequently ground, revealed that in the abscence of the grinding impulse
crystallisation of PEG6000 takes place in the same way as in dispersions ground immediately after preparation and then aged
for 1 month. Grinding solid dispersions immediately after preparation resulted in superior dissolution properties compared
with solid dispersions kept in the monolith-slab form and subsequently ground. This difference in dissolution properties was
found to be attributed to the drug and not to the polymer, more precisely, it was suggested that the drug particle size in
ground dispersions was smaller than in dispersions kept in the slab form and subsequently ground. These findings suggest that
grinding of solid dispersions immediately after preparation is the preparation method of choice instead of liquid filling
of hard gelatin capsules resulting in monoliths.
Authors:N. Molochnikova, V. Frenkel, and B. Myasoedov
Extraction of actinides has been examined in two-phase aqueous systems based on poly(ethylene glycol) (PEG) from sulfate solutions in the presence of potassium phosphotungstate, which forms strong complexes with ions of tri- and tetravalent transuranium elements. Extraction of these complexes by aqueous PEG solution is complete in contrast to that of penta- and hexavalent actinides. Conditions have been chosen for the separation of actinides in different oxidation states.
Authors:V. Shkinev, N. Molochnikova, T. Zvarova, B. Spivakov, B. Myasoedov, and Yu. Zolotov
The distribution of lanthanides and actinides in a two-phase liquid system obtained by mixing an aqueous solution of poly(ethylene glycol) and ammonium sulfate has been studied as a function of pH. Conditions are reported which provide the heterogeneity of the system suggested. It is shown that thorium and plutonium can be separated from transplutonium elements and lanthanides. Conditions have been chosen for quantitative group extraction of actinides and lanthanides.
Authors:W Zielenkiewicz, R Swierzewski, F Attanasio, and G Rialdi
of lysozyme–polyethylene glycol system were made by differential scanning
calorimetry, fluorescence and density techniques. The values of unfolding
enthalpies, ΔHNU, unfolding temperatures, Tm,
excess molar heat capacities, ΔCp,
and apparent molar volumes, VΦ
, were determined as functions of PEG concentration. The three PEGs of average
molecular mass (MW) 6000, 10000, 20000
were used as macromolecular crowding agents. The concentration of polymers
was changed in the range 0–30% mass per volume (w/v). The values of ΔHNU remained
constant with no dependence on PEG concentration, while PEG addition to buffered
lysozyme solutions caused linear decrease of Tm.
The values of ΔCp
and VΦ of lysozyme
dramatically changed in the range of 8–10% of PEG concentration. The
fluorescence spectroscopy was used in order to investigate the polymer influence
on possible solvent–lysozyme interactions. The electrical properties
of polymer–water and polymer–buffer systems, the dielectric constants
of solutions were determined with use of impedance spectroscopy.
Authors:N. Mallikarjuna, B. Govindaraj, A. Lagashetty, and A. Venkataraman
A novel combustion method of employing poly(ethylene glycol) with the precursor in a fixed ratio for the synthesis of ultrafine
γ-Fe2O3 through a self-propagating combustion synthesis is reported. Four different precursors viz. ferrous hydroxide, ferrous oxalate
dihydrate, ferric 8-hydroxyquinoline and ferric acetylacetonate are employed in this study for the conversion of these precursors
to ultrafine g-Fe2O3 particles. The as synthesized γ-Fe2O3 samples are characterized by XRD, SEM and thermal techniques. A case study for the synthesis of γ-Fe2O3 employing ferric acetyl acetonate as precursor is reported. The importance of employing thermal analysis techniques in understanding
the combustion synthesis is envisaged.
Authors:Mariano Pracella, Cristiano Pancrazi, Md. Minhaz-Ul Haque, and Aldo D'Alessio
min and containing 7 wt% MA were supplied by Sigma-Aldrich (Schnelldorf, Germany). Low molecular weight poly(ethyleneglycol) (PEG) with M w = 600 was supplied by Sigma-Aldrich (Milano, Italy). Cellulose fibres (Technocel 75), with average length of