scholarly journals Reversible switching of polymeric gel structure and property by solvent exchange

2021 ◽  
Author(s):  
Liju Xu ◽  
Dong Qiu
Keyword(s):  
Solvent Exchange ◽  
Gel Structure ◽  
Structure And Property ◽  
Polymeric Gel

scholarly journals Effect of Ethanol on the Textural Properties of Whey Protein and Egg White Protein Hydrogels during Water-Ethanol Solvent Exchange

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4417
Author(s):  
Christian Kleemann ◽  
Joël Zink ◽  
Ilka Selmer ◽  
Irina Smirnova ◽  
Ulrich Kulozik
Keyword(s):  
Whey Protein ◽  
Textural Properties ◽  
Egg White ◽  
Ion Concentration ◽  
Solvent Exchange ◽  
Gel Structure ◽  
Covalent Bonds ◽  
Egg White Protein ◽  
Gel Texture ◽  
Protein Hydrogels

This study aims at investigating the effect of ethanol (EtOH) on the textural properties of whey protein and egg white protein hydrogels. The hydrogels were produced by thermally induced gel formation of aqueous protein solutions. The water contained in the gel network was subsequently exchanged by EtOH to assess structural changes upon exposure of hydrogels to ethanolic aqueous phases. The textural properties of the hydrogel and alcogel samples were analyzed by uniaxial compression tests. For both protein sources, the hardness increased exponentially when pH and EtOH concentration were increased. This increase correlated with a shrinkage of the gel samples. The gel texture was found to be elastic at low EtOH concentrations and became stiff and hard at higher EtOH concentrations. It was found that the solvent exchange influences the ion concentration within the gels and, therefore, the interactions between molecules in the gel structure. Non-covalent bonds were identified as substantially responsible for the gel structure.

ANALYTICAL SOLUTIONS OF POLYMERIC GEL STRUCTURES UNDER BUCKLING AND WRINKLE

2011 ◽  
Vol 03 (02) ◽  
pp. 235-257 ◽  
Author(s):  
Z. S. LIU ◽  
S. SWADDIWUDHIPONG ◽  
F. S. CUI ◽  
W. HONG ◽  
Z. SUO ◽  
...  
Keyword(s):  
Thin Film ◽  
Analytical Solutions ◽  
Critical Stress ◽  
Chemical Potential ◽  
Slenderness Ratio ◽  
Experimental Studies ◽  
Structure Design ◽  
Inhomogeneous Field ◽  
Gel Structure ◽  
Polymeric Gel

One of the unique properties of polymeric gel is that the volume and shape of gel can dramatically change even at mild variation of external stimuli. Though a variety of instability patterns of slender and thin film gel structures due to swelling have been observed in various experimental studies, many are not well understood. This paper presents the analytical solutions of swelling-induced instability of various slender and thin film gel structures. We have adopted the well developed constitutive relation of inhomogeneous field theory of a polymeric network in equilibrium with a solvent and mechanical load or constraint with the incremental modulus concept for slender beam and thin film gel structures. The formulas of buckling and wrinkle conditions and critical stress values are derived for slender beam and thin film gel structures under swelling-induced instability using nonlinear buckling theories of beam and thin film structures. For slender beam structure, we construct the stability diagram with the distinct stable and unstable zones. The critical slenderness ratio and corresponding critical stresses are provided for different dimensionless material parameters. For thin film gel structures, we consider the thin film gel on an elastic foundation with different stiffness. The analytical solutions of critical stress and corresponding wrinkle wavelength, as well as buckling condition (or critical chemical potential) are given. These analytical solutions will provide a guideline for gel structure design used in polymeric gels MEMS and NEMS structures such as sensors and actuators. More importantly, the work provides a theoretical foundation of gel structure buckling and wrinkle, instability phenomena are different from normal engineering or material buckling.

Effect of Mold Temperature on Structure and Property Variations of PBT Injection Moldings in the Thickness Direction

2004 ◽  
Vol 19 (3) ◽  
pp. 303-307 ◽  
Author(s):  
M. Shibaya ◽  
H. Ishihara ◽  
K. Yamashita ◽  
N. Yoshihara ◽  
C. Nonomura
Keyword(s):  
Mold Temperature ◽  
Thickness Direction ◽  
Structure And Property

scholarly journals Solvent-exchange process in MOF ultrathin films and its effect on CO2 and methanol adsorption

2021 ◽  
Vol 590 ◽  
pp. 72-81
Author(s):  
M.A. Andrés ◽  
P. Fontaine ◽  
M. Goldmann ◽  
C. Serre ◽  
O. Roubeau ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Exchange Process ◽  
Solvent Exchange ◽  
Methanol Adsorption

scholarly journals Green Solvents as an Alternative to DMF in ZIF-90 Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1573
Author(s):  
Aljaž Škrjanc ◽  
Ciara Byrne ◽  
Nataša Zabukovec Logar
Keyword(s):  
Room Temperature ◽  
Product Yield ◽  
Solvent Exchange ◽  
Green Solvents ◽  
Zeolitic Imidazolate Framework ◽  
Short Treatment ◽  
Molar Ratios ◽  
Primary Particles ◽  
High Product Yield

The use of green solvents as an alternative to dimethylformamide (DMF) in the synthesis of zeolitic imidazolate framework-90 (ZIF-90) was investigated. Two biobased aprotic dipolar solvents CyreneTM and γ-valerolactone (GVL) proved to successfully replace DMF in the synthesis at room temperature with a high product yield. While the CyreneTM—based product shows reduced porosity after activation, the use of GVL resulted in materials with preserved crystallinity and porosity after activation, without prior solvent exchange and a short treatment at 200 °C. The primary particles of 30 nm to 60 nm in all products further form agglomerates of different size and interparticle mesoporosity, depending on the type and molar ratios of solvents used.

scholarly journals Impact of the Simulated Gastric Digestion Methodology on the In Vitro Intestinal Proteolysis and Lipolysis of Emulsion Gels

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 321
Author(s):  
Camila Mella ◽  
Michelle Quilaqueo ◽  
Rommy N. Zúñiga ◽  
Elizabeth Troncoso
Keyword(s):  
Heat Treatment ◽  
Protein Isolate ◽  
Gastric Digestion ◽  
Human Gastrointestinal Tract ◽  
Gel Structure ◽  
Intestinal Digestion ◽  
Food Digestion ◽  
The Impact ◽  
Digestion Methods

The aim of this work was to study the impact of the methodology of in vitro gastric digestion (i.e., in terms of motility exerted and presence of gastric emptying) and gel structure on the degree of intestinal proteolysis and lipolysis of emulsion gels stabilized by whey protein isolate. Emulsions were prepared at pH 4.0 and 7.0 using two homogenization pressures (500 and 1000 bar) and then the emulsions were gelled by heat treatment. These gels were characterized in terms of texture analysis, and then were subjected to one of the following gastric digestion methods: in vitro mechanical gastric system (IMGS) or in vitro gastric digestion in a stirred beaker (SBg). After gastric digestion, the samples were subjected to in vitro intestinal digestion in a stirred beaker (SBi). Hardness, cohesiveness, and chewiness were significantly higher in gels at pH 7.0. The degree of proteolysis was higher in samples digested by IMGS–SBi (7–21%) than SBg–SBi (3–5%), regardless of the gel’s pH. For SBg–SBi, the degree of proteolysis was not affected by pH, but when operating the IMGS, higher hydrolysis values were obtained for gels at pH 7.0 (15–21%) than pH 4.0 (7–13%). Additionally, the percentage of free fatty acids (%FFA) released was reduced by 47.9% in samples digested in the IMGS–SBi. For the methodology SBg–SBi, the %FFA was not affected by the pH, but in the IMGS, higher values were obtained for gels at pH 4.0 (28–30%) than pH 7.0 (15–19%). Our findings demonstrate the importance of choosing representative methods to simulate food digestion in the human gastrointestinal tract and their subsequent impact on nutrient bioaccessibility.

ChemInform Abstract: CORRELATIONS OF SOLVENT-EXCHANGE ACTIVATION ENTHALPIES

1978 ◽  
Vol 9 (41) ◽  
Author(s):  
L. L. RUSNAK ◽  
E. S. YANG ◽  
R. B. JORDAN
Keyword(s):  
Solvent Exchange
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