Effects of Grafting Azacrown Ether on Thermal and Swelling Properties of Chitosan Films

<p>Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by <i>N,N'</i>-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from <a>2-aminoethyl methacrylate </a>hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p>

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MONOLAYERS LENGMYUR AZAKRAUN-ESSENTIAL DERIVATIVES OF CALIXES[4]ARENA

EurasianUnionScientists ◽

10.31618/esu.2413-9335.2018.1.56.62-64 ◽

2018 ◽

Vol 1 (11(56)) ◽

pp. 62-64

Author(s):

A.A. Muravev ◽

E.A. Ivanova ◽

A.T. Yakupov

Keyword(s):

Aggregation Behavior ◽

Langmuir Films ◽

Azacrown Ether ◽

Derivatives Of

In this work, aggregation behavior of azacrown-ether derivatives on a macrocyclic calix[4]arene scaffold within ultrathin Langmuir films on water subphase is considered.

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Methods for analysis and testing of coal and coke. Caking and swelling properties of coal

10.3403/30306483 ◽

1942 ◽

Keyword(s):

Swelling Properties

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Chitosan as a Protective Matrix for the Squaraine Dye

Materials ◽

10.3390/ma14051171 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1171

Author(s):

Halina Kaczmarek ◽

Patryk Rybczyński ◽

Piotr Maćczak ◽

Aleksander Smolarkiewicz-Wyczachowski ◽

Marta Ziegler-Borowska

Keyword(s):

Solid State ◽

Uv Radiation ◽

Dye Degradation ◽

Protective Coatings ◽

Protective Action ◽

High Energy ◽

Modified Chitosan ◽

Dye Release ◽

Squaraine Dye ◽

Chitosan Films

Chitosan was used as a protective matrix for the photosensitive dye-squaraine (2,4-bis[4-(dimethylamino)phenyl]cyclobutane-1,3-diol). The physicochemical properties of the obtained systems, both in solution and in a solid-state, were investigated. However, it was found that diluted chitosan solutions with a few percent additions of dye show an intense fluorescence, which is suppressed in the solid-state. This is related to the morphology of the heterogeneous modified chitosan films. The important advantage of using a biopolymer matrix is the prevention of dye degradation under the influence of high energy ultraviolet (UV) radiation while the dye presence improves the chitosan heat resistance. It is caused by mutual interactions between macromolecules and dye. Owing to the protective action of chitosan, the dye release in liquid medium is limited. Chitosan solutions with a few percent additions of squaraine can be used in biomedical imaging thanks to the ability to emit light, while chitosan films can be protective coatings resistant to high temperatures and UV radiation.

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Chitosan Films Obtained from Brachystola magna (Girard) and Its Evaluation on Quality Attributes in Sausages during Storage

Molecules ◽

10.3390/molecules26061782 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1782

Author(s):

Juan Manuel Tirado-Gallegos ◽

Paul Baruk Zamudio-Flores ◽

Miguel Espino-Díaz ◽

René Salgado-Delgado ◽

Gilber Vela-Gutiérrez ◽

...

Keyword(s):

Weight Loss ◽

Lipid Oxidation ◽

Meat Products ◽

Water Vapor Permeability ◽

Good Alternative ◽

Quality Attributes ◽

Vapor Permeability ◽

Biodegradable Films ◽

Molecular Weights ◽

Chitosan Films

High molecular weight chitosan (≈322 kDa) was obtained from chitin isolated from Brachystola magna (Girard) to produced biodegradable films. Their physicochemical, mechanical and water vapor permeability (WVP) properties were compared against commercial chitosan films with different molecular weights. Brachystola magna chitosan films (CFBM) exhibited similar physicochemical and mechanical characteristics to those of commercial chitosans. The CFBM films presented lower WVP values (10.01 × 10−11 g/m s Pa) than commercial chitosans films (from 16.06 × 10−11 to 64.30 × 10−11 g/m s Pa). Frankfurt-type sausages were covered with chitosan films and stored in refrigerated conditions (4 °C). Their quality attributes (color, weight loss, pH, moisture, texture and lipid oxidation) were evaluated at 0, 5, 10, 15 and 20 days. Sausages covered with CFMB films presented the lowest weight loss (from 1.24 to 2.38%). A higher increase in hardness (from 22.32 to 30.63 N) was observed in sausages covered with CFMB films. Compared with other films and the control (uncovered sausages), CFMB films delay pH reduction. Moreover, this film presents the lower lipid oxidation level (0.10 malonaldehyde mg/sample kg). Thus, chitosan of B. magna could be a good alternative as packaging material for meat products with high-fat content.

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Evaluation of swelling properties and drug release from mechanochemical pre-gelatinized glutinous rice starch matrix tablets by near infrared spectroscopy

Journal of Near Infrared Spectroscopy ◽

10.1177/0967033520982351 ◽

2021 ◽

pp. 096703352098235

Author(s):

Tomomi Takaku ◽

Yusuke Hattori ◽

Tetsuo Sasaki ◽

Tomoaki Sakamoto ◽

Makoto Otsuka

Keyword(s):

Drug Release ◽

Near Infrared ◽

Nir Spectroscopy ◽

Matrix Tablets ◽

Rice Starch ◽

Release Time ◽

Swelling Properties ◽

X Ray ◽

Glutinous Rice ◽

Pharmaceutical Properties

The effect of grinding on the pharmaceutical properties of matrix tablets consisting of ground glutinous rice starch (GRS) and theophylline (TH) was predicted by near infrared (NIR) spectroscopy. Ground GRS samples were prepared by grinding GRS in a planetary ball mill for 0-120 min, measured by X-ray diffractometry (XRD) and NIR, and then evaluated for crystallinity (%XRD) based on XRD profiles. Tablets containing TH (5 w/w%), ground GRS (94 w/w%), and magnesium stearate (1 w/w%) were formed by compression. Gel-forming and drug-release processes of the tablets were measured using a dissolution instrument with X-ray computed tomography (XCT). Swelling ratio (SWE) and mean drug-release time (MDT) were evaluated based on XCT and drug-release profiles, respectively. Calibration models for predicting percent %XRD, MDT, and SWE were constructed based on the NIR of ground GRS using partial least-squares. The results indicated the possibility of controlling the pharmaceutical properties of matrix tablets by altering the pre-gelatinization of GRS based on changes in their NIR spectra during the milling process.

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Combined effect of mineralogical and chemical parameters on swelling behaviour of expansive soils

Scientific Reports ◽

10.1038/s41598-021-95746-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bendadi Hanumantha Rao ◽

Peddireddy Sreekanth Reddy ◽

Bijayananda Mohanty ◽

Krishna R. Reddy

Keyword(s):

Expansive Soils ◽

Research Work ◽

Swelling Pressure ◽

Combined Effect ◽

Practical Significance ◽

Chemical Compositions ◽

Chemical Parameters ◽

Swelling Behaviour ◽

Mineral Contents ◽

Swelling Properties

AbstractMicrolevel properties such as mineralogical and chemical compositions greatly control the macro behaviour of expansive soils. In this paper, the combined effect of mineral (i.e. montmorillonite, MMC) and chemical contents (i.e. Ca and Na in their total (T), leachable (L) and exchangeable form (CEC)) on swelling behaviour is investigated in a comprehensive way. Several 3-dimensional (3D) graphs correlating MMC and Ca/Na ratio, together, with swelling property (swelling potential, Sa, and swelling pressure, Sp) are developed. 3D plots, in general, portrayed a non-linear relationship of Sa and Sp with MMC and Ca/Na ratio, together. It is hypothesized that swelling initially is triggered by chemical parameters due to their quick and rapid ionization capability, but the overall swelling phenomenon is largely controlled by MMC. It is importantly found that expansive soils are dominant with divalent Ca++ ions up to MMC of 67% and beyond this percentage, monovalent Na+ ions are prevalent. From the interpretation of results, the maximum Sa of 18% and Sp of 93 kPa is measured at MMC of 43%, (Ca/Na)T of 10–14 and (Ca/Na)L of 2–7. It is concluded from study that total CEC + MMC for determining Sa and (Ca/Na)T + MMC for determining Sp are superior parameters to be considered. The findings of the study also excellently endorsed the results of Foster32, who stated that ionization of Na or Ca depends on the constituent mineral contents. The findings presented herein are unique, interesting and bear very practical significance, as no earlier research work reported such findings by accounting for chemical and mineralogical parameters impact, in tandem, on swelling properties.

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Understanding the Barrier and Mechanical Behavior of Different Nanofillers in Chitosan Films for Food Packaging

Polymers ◽

10.3390/polym13050721 ◽

2021 ◽

Vol 13 (5) ◽

pp. 721 ◽

Cited By ~ 1

Author(s):

João Pires ◽

Camila Damásio de Paula ◽

Victor Gomes Lauriano Souza ◽

Ana Luísa Fernando ◽

Isabel Coelhoso

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

Food Packaging ◽

Scientific Research ◽

Barrier Properties ◽

Plastic Pollution ◽

Functional Attributes ◽

Chitosan Films ◽

Commercial Applications ◽

Innovative Techniques

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties.

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