scholarly journals Physicochemical Properties of Solutions of Polyvinyl Alcohol (PVA) of Different Molecular Weights

2021 ◽  
Vol 6 (2) ◽  
pp. 242-248
Author(s):  
V. V. Chekanova ◽  
◽  
Yu. S. Pakhomova ◽  
A. M. Kompaniets ◽  
V. A. Kireev ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Physicochemical Properties ◽  
Dynamic Viscosity ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
Molecular Masses ◽  
Pva Solutions

The physicochemical properties (surface tension, dynamic viscosity, crystallization and melting temperatures) of polyvinyl alcohol solutions of molecular weight 9, 31 and 72 kDa have been studied. The surface tension and the critical concentration of micelle formation were determined by the method of stalogometry, and the dynamic viscosity was determined using an Oswald viscometer. The crystallization and melting temperatures were determined in a cooled modified chamber of the UOP-6 software freezer at a rate of 2°C/min. Cryomicroscopic studies were carried out on a polarizing microscope "MIN-8". The surface tension reflects the interaction of PVA solutions with the lipid layer of biomembranes and indicates the hydrophobic properties of substances. The viscosity of PVA solutions characterizes their interaction with water molecules and reflects hydrophilic interactions. The purpose of the study is to determine the physicochemical properties of PVS that characterize the hydrophilic-hydrophobic interactions in the studied solutions and the micelle formation of PVА solutions of different molecular weights. Materials and methods. Studies of the dynamic viscosity and density of 0.1%-1% PVA solutions of molecular weight 9, 31 kDa showed that these parameters increase with increasing PVA concentration, which leads to increased hydrophilicity of the solutions. Results and discussion. It was shown that the surface tension of PVA solutions decreases with increasing concentration, which leads to a decrease in the hydrophobic properties of the polymer. It was found that in 0.5% PVА solutions of molecular weight 9 and 31 kDa the crystallization and melting temperatures decrease from -5 to -6°C. At these temperatures, crystallization and melting of the solutions begin. Conclusion. The study of micelle formation in PVА solutions of different molecular masses was carried out, surface tension isotherms were constructed, and the break point on the isotherm corresponding to the CCM was determined. The values of the critical concentration of micelle formation of PVА of molecular masses 9, 31, 72 kDa were determined. Hydrophobic links of PVА of molecular masses 9 and 31 kDa form hydrophobic cavities in the micelle structure, which can reduce recrystallization activity

scholarly journals Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles’ Micromeritics

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1049 ◽  
Author(s):  
Rosalía Rodríguez-Dorado ◽  
Clara López-Iglesias ◽  
Carlos García-González ◽  
Giulia Auriemma ◽  
Rita Aquino ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Textural Properties ◽  
Supercritical Drying ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Molecular Weights ◽  
Nanostructured Particles

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

scholarly journals PECULARITIES OF MICELLE FORMATION OF PENTACYCLIC GLYCOSIDES IN AQUEOUS SOLUTIONS

2021 ◽  
Vol 64 (4) ◽  
pp. 26-33
Author(s):  
Natalia V. Mironenko ◽  
Irina V. Shkutina ◽  
Vladimir F. Selemenev
Keyword(s):  
Surface Tension ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Aqueous Solutions ◽  
Hydrodynamic Radius ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Cylindrical Shape ◽  
Scattering Method ◽  
Dynamic Light Scattering Method

The regularities of changes in structural characteristics during the formation of associates in micellar aqueous solutions of triterpene saponins Quillaja Saponin and Sapindus Mukorossi are considered. The dependence of surface tension and adsorption on the concentration of an aqueous saponin solution is analyzed, and the values of surface activity and parameters of the adsorption layer are calculated. The average values of diffusion coefficients for spherical and cylindrical micelles are determined based on the measurement of the solution viscosity. The effect of the electrolyte solution on the surface tension and viscosity of glycoside solutions is studied: when the electrolyte is introduced into the saponin solution, the surface tension decreases, which leads to a shift in the critical concentration of micelle formation towards lower concentrations. The introduction of potassium chloride electrolyte reduces the degree of ionization and, as a result of suppressing the electroviscosity effect, leads to a decrease in the viscosity of the solution. The dynamic light scattering method is used to determine the size of glycoside aggregates. It is established that there are aggregates of several sizes in an aqueous solution of saponin. The size and shape of aggregates were calculated using the concepts of micelle packing parameters. In the region of very low concentrations of glycoside solutions, when approaching the critical concentration of micelle formation in the solution, there are spherical micelles. A further increase in the saponin concentration in the solution leads to a decrease in the content of structures with a hydrodynamic radius of 50-80 nm and the appearance of larger agglomerates with sizes greater than 100 nm. It was found that micelles acquire a less hydrated and more densely packed cylindrical shape in the concentration range of 1.7-2.6 mmol/dm3. Compaction of associates leads to an increase in the content of particles with a hydrodynamic radius of 150-250 nm and larger ones, and their presence predicts the appearance of larger agglomerates. Analyzing the data obtained using the dynamic light scattering method, it can be concluded that aggregates of several sizes co-exist in the volume of aqueous saponin solutions at certain concentrations.

Aging Study of Gold Nanoparticles Functionalized with Chitosan in Aqueous Solutions

2017 ◽  
Vol 68 (10) ◽  
pp. 2385-2388
Author(s):  
Raoul Vasile Lupusoru ◽  
Laurentiu Simion ◽  
Ion Sandu ◽  
Daniela Angelica Pricop ◽  
Aurica Chiriac ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Aqueous Solutions ◽  
Colloidal Stability ◽  
Chemical Reduction ◽  
Storage Conditions ◽  
Chemical Reduction Method ◽  
Molecular Weights ◽  
Aging Period ◽  
Aging Study

We studied the way in which stability and physicochemical properties of gold (Au) nanoparticles (NP) coated with chitosan are influenced by the molecular weight of chitosan and Au precursor concentration when samples are subjected to aging. Pharmaceutical use of AuNPs coated with chitosan is closely related to stability and physicochemical properties in relation to storage conditions and processing. For this purpose, series of AuNPs of different sizes were prepared by aqueous chemical reduction method using chitosan with various molecular weights as template. The physicochemical properties and stability at room temperature of AuNPs in aqueous solutions of chitosan have been investigated by following the temporal evolution of surface plasmon absorbance, Zeta potential, average dimension, and Au-chitosan interaction, after synthesis and through a period of 24 months. In our experiment, during the observed aging period, the AuNPs coated with chitosan presented a better colloidal stability, while using chitosan with medium molecular weight and medium concentration of Au precursor.

EFFECTS OF ELECTRICAL CURRENT FREQUENCY ON THE PHYSICOCHEMICAL CHARACTERISTICS OF WASTEWATER

2021 ◽  
pp. 55-61
Author(s):  
Ba
Keyword(s):  
Surface Tension ◽  
Physicochemical Properties ◽  
Electric Fields ◽  
Dynamic Viscosity ◽  
Growth And Development ◽  
Electrical Current ◽  
Specific Weight ◽  
Physicochemical Characteristics ◽  
Current Frequency ◽  
Treatment Regimes

Water plays a crucial role in the growth and development of species on Earth. Changes in the physicochemical properties of water have a large effect on human activities as well. Researchers have studied and evaluated the effects of electrical current frequency (f = 0÷2.000 Hz) on the physicochemical properties (surface tension, dynamic viscosity, specific weight) of wastewater. The effect of electric fields on the physicochemical properties of water, allows it to identify the optimal treatment regimes that promote the intensification of various processes taking place in an aqueous medium or in the presence of water.

scholarly journals High Performance Conditioning Shampoo with Hyaluronic Acid and Sustainable Surfactants

Cosmetics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 71
Author(s):  
Kelly Yorke ◽  
Samiul Amin
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Hyaluronic Acid ◽  
High Performance ◽  
Low Cost ◽  
Hair Follicles ◽  
Shear Rates ◽  
Molecular Weights ◽  
Surface Activity Properties ◽  
Alkyl Polyglucoside

Recently, consumers have become invested in more natural and sustainable ingredients contained in personal care products. Unfortunately, cationic surfactants are still heavily relied on as primary conditioning agents in products such as conditioning shampoos because of their ability to cling well to the negatively charged surface of hair follicles. Additionally, sulfates are utilized as cleansing agents because they are highly effective and low cost. The objective of this study is to find a more sustainable formulation for a conditioning shampoo without compromising the desired wet combing, rheological, and surface activity properties. The systems which were investigated contained hyaluronic acid (HA) at a variety of molecular weights and concentrations, in combination with a surfactant, either acidic sophorolipid (ASL) or alkyl polyglucoside (APG), and varying the presence of sodium chloride. A Dia-stron was utilized to test the wet combing force, a rheometer recorded the viscosity at various shear rates, and a tensiometer measured the surface tension of the samples before a visual foaming study was conducted. Molecular weight and concentration seemed to have a large impact on wet combing force, as well as rheology, with the largest molecular weight and concentration producing the lowest friction coefficient and desired rheological profile. The addition of a surfactant significantly aids in the reduction in surface tension and increased foamability. Therefore, the optimal system to achieve the largest reduction in wet combing force, large viscosity with shear-thinning behavior, and relatively low surface tension with decent foaming is composed of 1% HA at 800 kDa, 10% ASL and 1% NaCl. This system shows a viable sulfate-free and silicone-free option that can achieve both conditioning and cleansing.

High-Throughput Synthesis of Oligo(ε-caprolactone) / Oligotetrahydrofuran Based Polyurethanes

MRS Advances ◽  
2018 ◽  
Vol 3 (49) ◽  
pp. 2965-2973
Author(s):  
M. Balk ◽  
A. Lendlein ◽  
M. Behl
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
High Throughput ◽  
Melting Transition ◽  
Multiblock Copolymers ◽  
Molecular Weights ◽  
Melting Temperatures ◽  
End Groups ◽  
Model Components ◽  
End Group

ABSTRACTRobot assisted synthesis as part of high-throughput (HT) technology can assist in the creation of polymer libraries, e.g. polymers with a variety of molecular weights, by automatizing similar reactions. Especially for multiblock copolymers like polyurethanes (PUs) synthesized from telechels via polyaddition reaction, the adjustment of equivalent molar amounts of reactants requires a comprehensive investigation of end group functionality.In this work, PUs based on oligo(ε-caprolactone) (OCL) / oligotetrahydrofuran (OTHF) as model components were designed utilizing HT synthesis enabling the quantitative determination of the optimized ratio between reactive end-groups via fully automated syntheses without major characterization effort of end group functionality. The semi-crystalline oligomeric telechelics were connected with a diisocyanate and OCL with a molecular weight of 2, 4, or 8 kg∙mol-1 was integrated. Here, optimized molecular weights between 90 ± 10 kg∙mol-1 (in case of OCL 8 kg∙mol-1) and 260 ± 30 kg∙mol-1 (in case of OCL 2 kg∙mol-1) were obtained with an isocyanate content of 120 mol%, whereby 100 mol% of isocyanate groups resulted only in molecular weights between 60 ± 6 kg∙mol-1 (OCL 8 kg∙mol-1) and 80 ± 10 kg∙mol-1 (OCL 2 kg∙mol-1). In addition to the optimized ratio between isocyanate and hydroxy end groups, quantitative influences of the OCL chain length and overall molecular weights of PUs on thermal and mechanical properties were detected. The melting temperatures (Tms) of OCL and OTHF domains were well separated for PUs of low molecular weight, the temperature interval between the Tms decreased when the molecular weight of the PUs was increased, and were even overlapping towards one broad Tm, when OCL 2 kg∙mol-1 was incorporated. The storage modulus E’ was highly dependent on OCL chain length exhibiting an increase with increasing molecular weight of OCL from 220 MPa to 440 MPa at 0 °C and decreased with increasing chain length of PUs. The elongation at break (εb) was analyzed below and above Tm of OTHF resulting in εb = 780-870% at 0 °C and εb = 510-830% at 30 °C for PUs of high molecular weight. Accordingly, stretchability of PUs was almost independent of the state of OTHF (semi crystalline or amorphous) but correlated with the OCL precursor chain length (increasing εb with increasing chain length) and overall molecular weight of PUs (PUs at higher molecular weight exhibited higher εb). Hence, the analysis of these quantitative influences between macromolecular structure of multiblock copolymers and the resulting properties (well separated Tms versus overlapping melting transition, improvement of stretchability) would enable the design of new tailored PUs.

scholarly journals Incorrect Molecular Weights due to inaccurate Prestained Protein Molecular Weight Markers that are used for Gel Electrophoresis and Western Blotting

2020 ◽  
Author(s):  
Rômulo Leão Silva Neris ◽  
Ajuni Kaur ◽  
Aldrin V. Gomes
Keyword(s):  
Molecular Weight ◽  
Molecular Mass ◽  
Western Blotting ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Protein Band ◽  
Molecular Weights ◽  
Molecular Masses ◽  
Protein Molecular Weight

ABSTRACTThe most widely used Western blotting protein standards are prestained proteins of known molecular mass (kDa). They are also utilized for sodium dodecyl sulphate (SDS) Polyacrylamide Gel Electrophoresis (PAGE) to determine the molecular mass of proteins separated by electrophoresis. The objective of this study was to assess the reliability of different commercially available protein standards in predicting accurate protein molecular weights. We performed this experiment by running Criterion TGX gels with five prestained protein standards (Thermo Fisher SeeBlue Plus 2, Bio-Rad Precision Plus Protein Dual-color, Thermo Fisher Spectra Multi-color, Novex-Sharp Pre-stained, and Invitrogen iBright Pre-Stained). To evaluate their accuracy, we utilized highly purified Bovine Serum Albumin (BSA, 66.44 kDa) and Cytochrome C (Cyto C, 11.62 kDa). We also made use of the dimers of BSA (132.88 kDa) and Cyt C (23.24 kDa) that are present on SDS-PAGE gels. Our results suggest that three of the standards were less accurate at higher molecular masses with the iBright marker having the highest error in determining the expected 132.88 kDa molecular weight. The SeeBlue Plus 2 was accurate at identifying the 132.88 kDa molecular weight protein band but was less reliable for the three other lower molecular weight proteins. These findings have significant implications for the determination of protein masses because researchers rely on these standards to evaluate the molecular masses of their protein(s). We suggest that at least two different protein standards should be initially used in electrophoresis gels and for Western blotting in order to get accurate protein molecular weight results.

scholarly journals Aqueous polyvinyl alcohol solution foaming at different molecular masses

2021 ◽  
Vol 16 (4) ◽  
pp. 337-344
Author(s):  
A. A. Akimova ◽  
V. A. Lomovskoy ◽  
I. D. Simonov-Emel’yanov
Keyword(s):  
Molecular Weight ◽  
Polyvinyl Alcohol ◽  
Solution Structure ◽  
Water Solution ◽  
Solution Temperature ◽  
Process Conditions ◽  
Molecular Weights ◽  
Foaming Process ◽  
Pva Solutions ◽  
Main Component

Objectives. Investigation of aqueous polyvinyl alcohol (PVA) foaming process and the influence of its water solution structure, when possessed of different molecular weights and concentrations, on foaming multiplicity.Methods. Solution foaming analysis was performed on the data of dynamic light scattering obtained on the Zetasizer Nano particle analyzer.Results. In this work, the foaming ability and foaming multiplicity of aqueous PVA solutions (as a main component for obtaining special-purpose foams) have been studied. It is shown that PVA solutions in water are colloidal dispersed systems consisting of different-sized associates (from 4.8 to 68.1 nm), depending on the molecular weight of PVA. Dependencies of aqueous PVA solution foaming multiplicities on the concentration, molecular weight, and solution temperature were given. Optimal values of concentration and molecular PVA weight, as well as optimal foaming process conditions from aqueous PVA solutions, were established.Conclusions. Increasing PVA concentrations in aqueous solutions cause foaming multiplicity to decrease for all molecular weights by 1.5 times, and increasing molecular weight increases foaming multiplicity by 2 times. The foaming ratio of aqueous PVA solutions with different concentrations and molecular weights (depending on a solution temperature characterized by a maximum of 30 °C) is associated with decreased viscosity and surface tension.

Synthesis and Characterisation of PLA-CO-PEG Copolymers

2012 ◽  
Vol 506 ◽  
pp. 178-181 ◽  
Author(s):  
C. Thanomsilp ◽  
U. Phetthianchai
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Thermal Degradation ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Molecular Weights ◽  
Copolymer Films ◽  
Melting Temperatures ◽  
Monomer Feed ◽  
Solution Cast

PLA-co-PEG copolymers synthesized through ring opening polymerization between a lactide monomer and PEG were solution-cast into films. The effect of the molecular weight of PEG and also the percentage of added PEG on the properties of the copolymers were studied. The molecular weight of PEG was 4000, 8000, and 20000 while the percentage of added PEG was varied from 10 to 50 mol%. The NMR spectrums confirmed that the ratio of PLA:PEG in the copolymers are close to the monomer feed of the respective monomers. DSC and TGA results showed that, compared to PLA, the PLA-co-PEG copolymers have slightly lower melting temperatures but similar thermal degradation temperatures. Both molecular weights and the percentage added of PEG influenced the properties of the films. As expected, the tensile strength and Youngs modulus of the PLA-co-PEG copolymer films were lower than that of neat PLA. Conversely, theelongation at break of the copolymer film was higher than that of the PLA when the molecular weight of PEG was 20000. This study suggests that high molecular weight PEG could be used to improve the flexibility of the polymer films.

scholarly journals Purification, Physicochemical Properties, and Antioxidant Activities of Two Low-Molecular-Weight Polysaccharides from Ganoderma leucocontextum Fruiting Bodies

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1145
Author(s):  
Xiong Gao ◽  
Jiayi Qi ◽  
Chi-Tang Ho ◽  
Bin Li ◽  
Yizhen Xie ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Antioxidant Activities ◽  
Molecular Surface ◽  
Low Molecular Weight ◽  
Fruiting Bodies ◽  
Nih3t3 Cells ◽  
Antioxidant Power ◽  
Molecular Weights ◽  
Ferric Reducing Antioxidant Power

Two low-molecular-weight polysaccharides (GLP-1 and GLP-2) were purified from Ganoderma leucocontextum fruiting bodies, and their physicochemical properties and antioxidant activities were investigated and compared in this study. The results showed that GLP-1 and GLP-2 were mainly composed of mannose, glucose, galactose, xylose, and arabinose, with weight-average molecular weights of 6.31 and 14.07 kDa, respectively. Additionally, GLP-1 and GLP-2 had a similar chain conformation, crystal structure, and molecular surface morphology. Moreover, GLP-1 exhibited stronger antioxidant activities than GLP-2 in five different assays: 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), hydroxyl radical, superoxide anion radical, ferric reducing antioxidant power (FRAP), and oxygen radical antioxidant capacity (ORAC). The main linkage types of GLP-1 were found to be →4)-α-D-Glcp-(1→, →4)-β-D-Glcp-(1→, →3)-β-D-Glcp-(1→, →6)-β-D-Galp-(1→, →6)-α-D-Glcp-(1→, →4,6)-α-D-Glcp-(1→, and Glcp-(1→ by methylation analysis and nuclear magnetic resonance (NMR) spectroscopy. In addition, GLP-1 could protect NIH3T3 cells against tert-butyl hydroperoxide (tBHP)-induced oxidative damage by increasing catalase (CAT) and glutathione peroxidase (GSH-Px) activities, elevating the glutathione/oxidized glutathione (GSH/GSSG) ratio, and decreasing the malondialdehyde (MDA) level. These findings indicated that GLP-1 could be explored as a potential antioxidant agent for application in functional foods.

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