Simple One Pot Preparation of Chemical Hydrogels from Cellulose Dissolved in Cold LiOH/Urea

In this work, non-derivatized cellulose pulp was dissolved in a cold alkali solution (LiOH/urea) and chemically cross-linked with methylenebisacrylamide (MBA) to form a robust hydrogel with superior water absorption properties. Different cellulose concentrations (i.e., 2, 3 and 4 wt%) and MBA/glucose molar ratios (i.e., 0.26, 0.53 and 1.05) were tested. The cellulose hydrogel cured at 60 °C for 30 min, with a MBA/glucose molar ratio of 1.05, exhibited the highest water swelling capacity absorbing ca. 220 g H2O/g dry hydrogel. Moreover, the data suggest that the cross-linking occurs via a basic Michael addition mechanism. This innovative procedure based on the direct dissolution of unmodified cellulose in LiOH/urea followed by MBA cross-linking provides a simple and fast approach to prepare chemically cross-linked non-derivatized high-molecular-weight cellulose hydrogels with superior water uptake capacity.

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Hydrogel Films Based on Chitosan and Oxidized Carboxymethylcellulose Optimized for the Controlled Release of Curcumin with Applications in Treating Dermatological Conditions

Molecules ◽

10.3390/molecules26082185 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2185

Author(s):

Mohamed Dellali ◽

Camelia Elena Iurciuc (Tincu) ◽

Corina Lenuța Savin ◽

Nawel Spahis ◽

M’hamed Djennad ◽

...

Keyword(s):

Carboxymethyl Cellulose ◽

Molar Ratio ◽

Cross Linking ◽

Oxidation Degree ◽

Molar Ratios ◽

Receptor Compartment ◽

Index Value ◽

Aldehyde Groups ◽

Hydrogel Films

Cross-linked chitosan (CS) films with aldehyde groups obtained by oxidation of carboxymethyl cellulose (CMC) with NaIO4 were prepared using different molar ratios between the CHO groups from oxidized carboxymethyl cellulose (CMCOx) and NH2 groups from CS (from 0.25:1 to 2:1). Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy demonstrated the aldehyde groups’ presence in the CMCOx. The maximum oxidation degree was 22.9%. In the hydrogel, the amino groups’ conversion index value increased when the -CHO/-NH2 molar ratio, cross-linking temperature, and time increased, while the swelling degree values decreased. The hydrogel films were characterized by scanning electron microscopy (SEM) and FTIR analysis. The curcumin encapsulation efficiency decreases from 56.74% to 16.88% when the cross-linking degree increases. The immobilized curcumin release efficiency (REf%) and skin membrane permeability were evaluated in vitro in two different pH solutions using a Franz diffusion cell, and it was found to decrease when the molar ratio -CH=O/NH2 increases. The curcumin REf% in the receptor compartment was higher at pH = 7.4 (18%- for the sample with a molar ratio of 0.25:1) than at pH = 5.5 (16.5%). The curcumin absorption in the skin membrane at pH = 5.5 (47%) was more intense than at pH = 7.4 (8.6%). The curcumin-loaded films’ antioxidant activity was improved due to the CS presence.

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SINTESIS DAN KARAKTERISASI SUPERABSORBEN DARI SELULOSA JERAMI PADI (Superabsorbent Synthesis and Characterization of Rice Straw Cellulose)

Jurnal Sains Terapan ◽

10.29244/jstsv.4.1.46-52 ◽

2014 ◽

Vol 4 (1) ◽

pp. 46-52

Author(s):

Wina Yulianti ◽

Farida Laila

Keyword(s):

Hydrogen Peroxide ◽

Rice Straw ◽

Potassium Hydroxide ◽

Water Solution ◽

Synthesis And Characterization ◽

Cross Linking ◽

Alkaline Ph ◽

Swelling Capacity ◽

Water Swelling

Copolymerization of cellulose from rice straw with acrylic acid and acrylamide produce biopolymer superabsorbent. Cellulose was purified from fat content by extraction with toluene:ethanol (2:1). Hemicelluloses and lignin were removal by using potassium hydroxide 5% and hydrogen peroxide 2% at alkaline pH. Cellulose yield obtained was 21.56%. FTIR spectra of lignin showed a loss of absorption at 1728 cm-1. Copolymerization was carried out at 65 C under nitrogen athmosphere. Initiator and cross linking agent used were potassium peroxodisulfate and N'N-methylene bis acrylamide. Superbasorben resulted from this experiment showed the water swelling capacity after 24 hour for the water, solution of 100 ppm of ammonium chloride, and urea respectively 387,11 g/g ; 193,47 g/g and 400,17 g/g.Keywords : superabsorbent, rice straw, swelling capacity

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One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

Materials ◽

10.3390/ma14205942 ◽

2021 ◽

Vol 14 (20) ◽

pp. 5942

Author(s):

Dongfei Xu ◽

Jiaan Ren ◽

Shengnan Yue ◽

Xiujing Zou ◽

Xingfu Shang ◽

...

Keyword(s):

Catalytic Properties ◽

Weak Acid ◽

Molar Ratio ◽

Weak Base ◽

Acid Base ◽

One Pot ◽

Catalyst Structure ◽

Molar Ratios ◽

One Pot Synthesis ◽

Catalytic Performances

A series of Al-P-O catalysts (Al-xP-O) were prepared using a P123-assisted one-pot method at different P/Al molar ratios and used for O-methylation of catechol and methanol. The influences of the P/Al molar ratio and P123 addition on catalyst structure and surface acid-base characteristics were investigated in detail. Increasing the P/Al molar ratio more favored crystalline aluminophosphate. The P123-assisted Al3+ and PO43− are known to be stabilized through weak steric force so that the formation of crystalline aluminophosphate could be inhibited at higher P/Al molar ratios. The results showed that the prepared Al-P-O catalysts possessed appropriate weak acid and weak base sites, which was beneficial to the reaction of catechol and methanol. The Al-1.1P-O catalyst synthesized with the assistance of P123 exhibited superior catalytic performances, with 52.5% catechol conversion and higher guaiacol selectivity of 97.6%.

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One-pot Preparation of Cu2(OH)3NO3 Nanosheets and Cu(OH)2 Nanowires

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681208666180601102915 ◽

2019 ◽

Vol 9 (4) ◽

pp. 467-471

Author(s):

Wenzhe Zhang ◽

Ailing Yang ◽

Xichang Bao

Keyword(s):

Crystal Structures ◽

Monoclinic Phase ◽

Orthorhombic Phase ◽

Molar Ratio ◽

X Ray Diffraction ◽

One Pot ◽

Molar Ratios ◽

Transmission Electron ◽

Reaction Solution ◽

Cuo Nanosheets

Introduction: By using Cu(NO3)2 as precursor and polyvinylpyrrolidone (PVP) as surfactant, nanosheets of Cu2(OH)3NO3, nanowires of Cu(OH)2 or the mixture of the two were prepared under different molar ratios of OH− to Cu2+. Materials and Methods: The crystal structures and morphologies of the products were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). Results: When the molar ratio of OH− to Cu2+ in reaction solution is lower than 1.28, pure Cu2(OH)3NO3 nanosheets were obtained. The thickness of one piece of nanosheet is about 167 nm. The Cu2(OH)3NO3 nanosheets consists of two types of crystal structures, monoclinic phase and orthorhombic phase. With increase of the molar ratio of OH− to Cu2+, the monoclinic phase of Cu2(OH)3NO3 was transferred to the orthorhombic phase of Cu2(OH)3NO3. When the molar ratio of OH− to Cu2+ is within 1.28-2.24, the product is the mixture of Cu2(OH)3NO3 nanosheets and Cu(OH)2 nanowires. And when this molar ratio is higher than 2.24, only Cu(OH)2 nanowires were produced. The lengths and the diameters of the Cu(OH)2 nanowires are in the region of 50-250 nm and 10 nm, respectively. Conclusion: The reason of the Cu2(OH)3NO3 nanosheets changing into the Cu(OH)2 nanowires is that the OH− anions replace the NO3 − anions in the layered Cu2(OH)3NO3 nanosheets, which causes the rupture of hydrogen bonds connecting the adjacent layers. The Cu(OH)2 nanowires were not stable and found to become spindled CuO nanosheets in air at room temperature.

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The Use of a Biopolymer Conjugate for an Eco-Friendly One-Pot Synthesis of Palladium-Platinum Alloys

Polymers ◽

10.3390/polym11121948 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1948 ◽

Cited By ~ 2

Author(s):

Daniele Silvestri ◽

Stanisław Wacławek ◽

Rohith K. Ramakrishnan ◽

Abhilash Venkateshaiah ◽

Kamil Krawczyk ◽

...

Keyword(s):

Green Synthesis ◽

Bimetallic Nanoparticles ◽

Catalytic Reduction ◽

Pt Nanoparticles ◽

Attenuated Total Reflection ◽

Molar Ratio ◽

One Pot ◽

Synthesis Conditions ◽

Molar Ratios ◽

Green Approach

Raising health and environmental concerns over the nanoparticles synthesized from hazardous chemicals have urged researchers to focus on safer, environmentally friendlier and cheaper alternatives as well as prompted the development of green synthesis. Apart from many advantages, green synthesis is often not selective enough (among other issues) to create shape-specific nanoparticle structures. Herein, we have used a biopolymer conjugate and Pd and Pt precursors to prepare sustainable bimetallic nanoparticles with various morphology types. The nanoparticles were synthesized by a novel green approach using a bio-conjugate of chitosan and polyhydroxybutyrate (Cs-PHB). The bio-conjugate plays the simultaneous roles of a reducing and a capping agent, which was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and energy dispersive X-ray spectrometry (EDS) analysis, proving the presence of a Cs-PHB layer on the surface of the prepared nanoparticles. The EDS profile also revealed the elemental structure of these nanoparticles and confirmed the formation of a Pd/Pt alloy. TEM morphological analysis showed the formation of star-like, octahedron or decahedron Pd/Pt nanoparticles, depending on the synthesis conditions. The bimetallic Pd/Pt nanoparticles synthesized with various Pd/Pt molar ratios were successfully applied for the catalytic reduction of 4-nitrophenol to 4-aminophenol by borohydride. The calculated κc values (ratio of kapp to the concentration of the catalyst) revealed that the decahedron nanoparticles (size of 15 ± 4 nm), synthesized at the molar ratio of 2:1 (Pd/Pt), temperature of 130 °C, 10 g/L of Cs-PHB conjugate and time of 30 min, exhibited excellent catalytic activity compared to other bimetallic nanoparticles reported in the literature.

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Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽

10.3390/catal11030346 ◽

2021 ◽

Vol 11 (3) ◽

pp. 346

Author(s):

Sonam Goyal ◽

Maizatul Shima Shaharun ◽

Ganaga Suriya Jayabal ◽

Chong Fai Kait ◽

Bawadi Abdullah ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalyst Support ◽

Oxidation Potential ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Optimum Parameters ◽

Reduction Of Co2 ◽

Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

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Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

Molecules ◽

10.3390/molecules26113317 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3317

Author(s):

Maria Carolina Pereira Gonçalves ◽

Jéssica Cristina Amaral ◽

Roberto Fernandez-Lafuente ◽

Ruy de Sousa Junior ◽

Paulo Waldir Tardioli

Keyword(s):

Oleic Acid ◽

Methyl Ethyl Ketone ◽

Molar Ratio ◽

Methyl Ethyl ◽

Sugar Ester ◽

Molar Ratios ◽

Emulsion Capacity ◽

Ping Pong ◽

Commercial Sugar ◽

Repeated Use

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

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Smart control of cotton fabric comfort by cross-linking thermo-responsive poly(2-(2-methoxyethoxy) ethoxyethyl methacrylate-co-ethylene glycol methacrylate)

Textile Research Journal ◽

10.1177/0040517516657061 ◽

2016 ◽

Vol 87 (13) ◽

pp. 1620-1630 ◽

Cited By ~ 18

Author(s):

Yangyi Chen ◽

Jie An ◽

Qi Zhong ◽

Peter Müller-Buschbaum ◽

Jiping Wang

Keyword(s):

Ethylene Glycol ◽

Cotton Fabric ◽

Random Copolymer ◽

Cotton Fabrics ◽

Molar Ratio ◽

Cross Linking ◽

Glycol Methacrylate ◽

Moisture Permeability ◽

Smart Control ◽

Fabric Comfort

The smart control of cotton fabric comfort by cross-linking thermo-responsive random copolymer is investigated. The monomers 2-(2-methoxyethoxy) ethoxyethyl methacrylate (MEO2MA) and ethylene glycol methacrylate (EGMA) with a molar ratio of 17:3 are selected to synthesize the thermo-responsive random copolymer poly(2-(2-methoxyethoxy) ethoxyethyl methacrylate- co-ethylene glycol methacrylate), abbreviated as P(MEO2MA- co-EGMA). By using citric acid as a cross-linking agent, the obtained P(MEO2MA- co-EGMA) is successfully immobilized onto cotton fabrics. Smart control is achieved from the thermo-responsive behavior of the copolymer. Cross-linked P(MEO2MA- co-EGMA) will collapse when the ambient temperature exceeds its transition temperature. Therefore, the formerly compact P(MEO2MA- co-EGMA) layer will switch to a porous structure, and the air/moisture permeability of the textiles is enhanced. As the comfort of the textiles is closely related to the air/moisture permeability, a smart control of the cotton fabric comfort can be realized. In addition, the softness of cotton fabrics with and without thermo-responsive polymers does not show a prominent change, even when the applied solution concentration is as high as 16% (wt%). On the contrary, the stiffness of the cotton fabric coated with poly( N-isopropylacrylamide) (PNIPAM) is significantly higher than the original cotton fabric, indicating that homo PNIPAM is less suitable for textiles used in daily lives. Moreover, the whiteness and mechanical properties are studied and stay unchanged after cross-linking. As a consequence, the introduction of P(MEO2MA- co-EGMA) into textiles can provide textiles with smart control of cotton comfort, and it will not influence the wearabilities of the textiles.

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Appearance, corrosion properties, and leach resistance of spruce and pine wood treated with Mea modified micronized copper preservative (MCu)

Holzforschung ◽

10.1515/hf-2013-0088 ◽

2014 ◽

Vol 68 (4) ◽

pp. 477-486 ◽

Cited By ~ 4

Author(s):

Myung Jae Lee ◽

Sedric Pankras ◽

Paul Cooper

Keyword(s):

Wood Species ◽

Wood Preservative ◽

Molar Ratio ◽

Corrosion Properties ◽

Pine Wood ◽

Molar Ratios ◽

Copper Leaching ◽

Mold Resistance ◽

Refractory Wood

Abstract Canadian refractory wood species treated with micronized copper (MCu) wood preservative become mottled and streaky in appearance. To overcome this issue, the MCu system was modified by adding small amounts of monoethanolamine (Mea). The modified systems were evaluated to clarify the role of Mea in terms of leaching, corrosion, and mold resistance of MCu systems. The mottled and streaky surface on treated spruce was prevented at Mea/Cu molar ratios between 0.7 and 1.5. Copper leaching remained modest and was only slightly higher than that of MCu alone up to a Mea/Cu molar ratio of 1.2. However, adding even a small amount of Mea to the MCu formulation increased fastener corrosion compared with MCu. Protonated Mea increased as more Mea was added and was identified as the main corrosion-causing electrolyte in the system.

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Hydrogen-bonded bent-core blue phase liquid crystal complexes containing various molar ratios of proton acceptors and donors

RSC Advances ◽

10.1039/c5ra26827c ◽

2016 ◽

Vol 6 (38) ◽

pp. 32319-32327 ◽

Cited By ~ 13

Author(s):

Chun-Chieh Han ◽

Yu-Chaing Chou ◽

San-Yuan Chen ◽

Hong-Cheu Lin

Keyword(s):

Liquid Crystal ◽

Chain Length ◽

Alkyl Chain ◽

Alkyl Chain Length ◽

Chiral Center ◽

Molar Ratio ◽

Core Complex ◽

Molar Ratios ◽

Phase Liquid ◽

Blue Phase

The molar ratio, alkyl chain length, lateral fluoro-substitution and the chiral center of H-bonded bent-core supramolecules would affect the BP ranges of BPLC complexes. H-bonded bent-core complex PIIIC9/AIIF* (3/7 mol mol−1) displayed the widest BPI range of ΔTBPI = 12 °C.

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