scholarly journals Cryostructuring of Polymeric Systems. 49. Unexpected “Kosmotropic-Like” Impact of Organic Chaotropes on Freeze–Thaw-Induced Gelation of PVA in DMSO

Gels ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 81 ◽  
Author(s):  
Vladimir Lozinsky ◽  
Olga Kolosova ◽  
Dmitrii Michurov ◽  
Alexander Dubovik ◽  
Viktor Vasil’ev ◽  
...  
Keyword(s):  
Guanidine Hydrochloride ◽  
Aqueous Media ◽  
Poly Vinyl Alcohol ◽  
Gel Formation ◽  
Polymeric Systems ◽  
Freeze Thaw ◽  
Structural Regularity ◽  
Huggins Constant ◽  
Key Factor ◽  
Activation Heat

Urea (URE) and guanidine hydrochloride (GHC) possessing strong chaotropic properties in aqueous media were added to DMSO solutions of poly(vinyl alcohol) (PVA) to be gelled via freeze–thaw processing. Unexpectedly, it turned out that in the case of the PVA cryotropic gel formation in DMSO medium, the URE and GHC additives caused the opposite effects to those observed in water, i.e., the formation of the PVA cryogels (PVACGs) was strengthened rather than inhibited. Our studies of this phenomenon showed that such “kosmotropic-like” effects were more pronounced for the PVACGs that were formed in DMSO in the presence of URE additives, with the effects being concentration-dependent. The additives also caused significant changes in the macroporous morphology of the cryogels; the commonly observed trend was a decrease in the structural regularity of the additive-containing samples compared to the additive-free gel sample. The viscosity measurements revealed consistent changes in the intrinsic viscosity, Huggins constant, and the excess activation heat of the viscosity caused by the additives. The results obtained evidently point to the urea-induced decrease in the solvation ability of DMSO with respect to PVA. As a result, this effect can be the key factor that is responsible for strengthening the structure formation upon the freeze–thaw gelation of this polymer in DMSO additionally containing additives such as urea, which is capable of competing with PVA for the solvent.

Entrapment of ethyl vanillin in calcium alginate and calcium alginate/poly(vinyl alcohol) beads

2013 ◽  
Vol 67 (2) ◽  
Author(s):  
Steva Levic ◽  
Verica Djordjevic ◽  
Nevenka Rajic ◽  
Milan Milivojevic ◽  
Branko Bugarski ◽  
...  
Keyword(s):  
Vinyl Alcohol ◽  
Calcium Alginate ◽  
Poly Vinyl Alcohol ◽  
Gel Formation ◽  
Ftir Analysis ◽  
Ethyl Vanillin ◽  
Freeze Thaw ◽  
Thermal Gravimetry ◽  
The Matrix ◽  
Cross Linker

AbstractElectrostatic extrusion was applied to the encapsulation of 3-ethoxy-4-hydroxybenzaldehyde (ethyl vanillin) in calcium alginate and calcium alginate/poly(vinyl alcohol) beads. The calcium alginate/poly(vinyl alcohol) hydrogel spheres were formed after contact with the cross-linker solution of calcium chloride, followed by the freeze-thaw method for poly(vinyl alcohol) gel formation. The entrapment of aroma in beads was investigated by FTIR and thermal analysis (thermogravimetry/differential thermal gravimetry; TGA/DTG). The mass loss in the temperature range of 150–300°C is related to degradation of the matrix and the release of ethyl vanillin. According to the DTG curve, the release of ethyl vanillin occurs at about 260°C. TGA measurements of the stored samples confirmed that formulations were stable for a period of one month. FTIR analysis provides no evidence for chemical interactions between flavour and alginate that would alter the nature of the functional groups in the flavour compound.

scholarly journals Self-Healing Polymer-Clay Hybrids by Facile Complexation of a Waterborne Polymer with a Clay

2021 ◽  
Author(s):  
Aranee Pleng Teepakakorn ◽  
Makoto Ogawa
Keyword(s):  
Vinyl Alcohol ◽  
Aqueous Media ◽  
Water Soluble ◽  
Poly Vinyl Alcohol ◽  
Self Healing ◽  
Soluble Polymer ◽  
Water Soluble Polymer ◽  
Smectite Clay

Water-induced self-healing materials were prepared by the hybridization of a water-soluble polymer, poly(vinyl alcohol), with a smectite clay by mixing in an aqueous media and subsequent casting. Without using chemical...

scholarly journals Enhancing the Freeze-Thaw Durability of Concrete Through Ice Recrystallization Inhibition by Poly(vinyl Alcohol)

2019 ◽  
Author(s):  
Zhengyao Qu ◽  
Shuaiqi Guo ◽  
Christian C. M. Sproncken ◽  
Romà Surís-Valls ◽  
qingliang yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vinyl Alcohol ◽  
Cement Hydration ◽  
Poly Vinyl Alcohol ◽  
Seasonal Temperature ◽  
Ice Recrystallization Inhibition ◽  
Ice Recrystallization ◽  
Freeze Thaw ◽  
Recrystallization Inhibition ◽  
Durability Of Concrete

Frost weathering of porous materials caused by seasonal temperature changes is a major source of damage to the world’s infrastructure and cultural heritage. Here we investigate poly(vinyl alcohol) (PVA) addition as a means to enhance the freeze-thaw durability of concrete without compromising its structural or mechanical integrity. We evaluate the ice recrystallization inhibition activity of PVA in a cementitious environment and the impact of PVA on key structural and mechanical properties, such as cement hydration (products), microstructure, strength, as well as freeze‑thaw resistance. We find that a low amount of PVA significantly reduces the surface scaling of concrete and displays excellent ice recrystallization inhibition in the saturated Ca(OH)<sub>2 </sub>solution which has a similar pH value as cement pore solution, while it does not affect cement hydration, microstructure, nor its mechanical properties. These findings contribute to new insights on freeze-thaw damage mechanism and more importantly we disclose a new direction for the design of concrete with excellent freeze‑thaw resistance.

Reaction of poly(vinyl alcohol) and dialdehydes during gel formation probed by 1H n.m.r.—a kinetic study

Polymer ◽  
1997 ◽  
Vol 38 (19) ◽  
pp. 4863-4871 ◽  
Author(s):  
E.W. Hansen ◽  
K.H. Holm ◽  
D.M. Jahr ◽  
K. Olafsen ◽  
Aa. Stori
Keyword(s):  
Kinetic Study ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Gel Formation

scholarly journals Cryostructuring of Polymeric Systems. 50.† Cryogels and Cryotropic Gel-Formation: Terms and Definitions

Gels ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 77 ◽  
Author(s):  
Vladimir Lozinsky
Keyword(s):  
Polymeric Materials ◽  
Gel Formation ◽  
Polymeric Systems ◽  
The Past ◽  
Marked Variability ◽  
Conference Presentations

A variety of cryogenically-structured polymeric materials are of significant scientific and applied interest in various areas. However, in spite of considerable attention to these materials and intensive elaboration of their new examples, as well as the impressive growth in the number of the publications and patents on this topic over the past two decades, a marked variability of the used terminology and definitions is frequently met with in the papers, reviews, theses, patents, conference presentations, advertising materials and so forth. Therefore, the aim of this brief communication is to specify the basic terms and definitions in the particular field of macromolecular science.

Cellulose acetate/poly(vinyl alcohol) hybrid fibrous mat containing tetracycline hydrochloride and phenytoin sodium: Morphology, drug release, antibacterial, and cell culture studies

2018 ◽  
Vol 33 (6) ◽  
pp. 597-611 ◽  
Author(s):  
Hamed Souriyan-Reyhani pour ◽  
Ramin Khajavi ◽  
Mohammad Esmaeil Yazdanshenas ◽  
Payam Zahedi ◽  
Mohammad Mirjalili
Keyword(s):  
Drug Release ◽  
Cellulose Acetate ◽  
Vinyl Alcohol ◽  
Aqueous Media ◽  
Tetracycline Hydrochloride ◽  
Diameter Distribution ◽  
Poly Vinyl Alcohol ◽  
Release Kinetic ◽  
Phenytoin Sodium ◽  
20 Nm

The objective of this study was to introduce an electrospun hybrid fibrous mat (a dual-fiber drug delivery system) based on cellulose acetate and poly(vinyl alcohol) containing tetracycline hydrochloride and phenytoin sodium, respectively. Characterization of samples was carried by morphology, drug release, cell cytotoxicity, adhesion, antibacterial property, and wettability investigations. The results showed a uniform shape and a narrow diameter distribution of fibers (between 160 ± 20 nm) for fabricated cellulose acetate/poly(vinyl alcohol) hybrid fibrous mat. The tetracycline hydrochloride release from cellulose acetate significantly decreased due to gel formation of poly(vinyl alcohol) in aqueous media. The best fit for drug release kinetic of hybrid sample was Higuchi model. Sample with tetracycline hydrochloride and phenytoin sodium drugs showed improved cell growth, viability, and antibacterial activity against Escherichia coli (~89%) and Staphylococcus aureus (~98%) in comparison with sample without drugs. The hydrophilic property of cellulose acetate/poly(vinyl alcohol) fibrous sample containing the drugs was also remarkable (~45°). To consider the obtained results, the presented hybrid fibrous mat shows a high potent for biomedical applications.

Water-induced helical supramolecular polymerization and gel formation of an alkylene-tethered perylene bisimide dyad

2017 ◽  
Vol 53 (1) ◽  
pp. 168-171 ◽  
Author(s):  
Xu Lin ◽  
Hiroki Kurata ◽  
Deepak D. Prabhu ◽  
Mitsuaki Yamauchi ◽  
Tomonori Ohba ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Supramolecular Polymers ◽  
Gel Formation ◽  
Perylene Bisimide ◽  
Supramolecular Polymerization ◽  
Lyotropic Mesophases

Linking two perylene bisimide dyes through an alkylene tether enforces aggregation in aqueous media, affording helical supramolecular polymers that can form gel-like lyotropic mesophases.

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