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1.
Carbohydr Polym ; 237: 116133, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32241408

RESUMO

To obtain efficient oil-water separation materials with responsiveness, cellulosic porous materials with switchable wettability in response to pH changes were developed by reacting cellulose acetoacetate sponges with alkylamines of varying carbon chain length via dynamic covalent enamine bonds. The resulting sponges reversibly changed between being superhydrophilic (θwater = 0°) and highly hydrophobic (maximal θwater = 146°) under suitable pH conditions while maintained the favorable porous structures. Notably, the functionalized sponges exhibited high and selective oil absorption capacity (40-80 g/g) and satisfying desorption ability of 80%, and could efficiently separate oil-water mixtures and emulsions with extremely high efficiency (> 99%) in a controllable manner. With the three-dimensional micro/nano porous structure, switchable wettability and intrinsic environmentally friendliness, the pH responsive cellulosic sponges developed here hold great potential in controllable oil-water separation and oily wastewater purification.

2.
Carbohydr Polym ; 234: 115934, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32070548

RESUMO

Microencapsulated phase change composite materials (MPCMs) with cellulose nanocrystals-composited poly (methyl methacrylate) (PMMA) as shell and n-eicosane as core was facially prepared via Pickering emulsion assisted solvent evaporation approach. PMMA and n-eicosane were dissolved in chloroform as the oil phase. Cellulose nanocrystals (CNC) can efficiently stabilize oil - in - water (O / W) emulsion, and the core-shell ratio will affect the thermal properties of MPCMs, study found that the optimal core-shell ratio was 1:2 and encapsulation ratio reached 58.2 %. The PMMA encapsulated MPCMs displayed a regular spherical shape sized in the range of 5-10 micrometers. They had favorable thermal stability and melting enthalpy of up to 150.8 J/g. Results of the thermal cycling tests showed melting enthalpy of MPCMs were maintained by over 99 % after 100 heating-cooling cycles. The proposed Pickering emulsion assisted solvent evaporation approach provides a potential way for industrial production of microencapsulated phase change materials.

3.
J Mol Graph Model ; 97: 107554, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32035312

RESUMO

The aggregation behaviors of methylcellulose (MC) in aqueous solution were investigated using all-atom molecular dynamic simulations (MD). The interactions between MC chains and water molecules at different temperatures were investigated by a series of MD analyses, such as the solvent accessible surface area, number of hydrogen bonds, radial distribution functions and the interaction energies. Constant temperature simulations and heating simulations of MC aqueous solution were carried out in this work. In the simulations at three constant temperatures (25 °C, 50 °C and 75 °C), the aggregation behaviors of MC chains were affected by the temperature. In the heating simulation (25 °C âˆ¼ 75 °C), temperature increases were accompanied by decreases in interactions between MC and water molecules, and by increases in interactions between MC chains, which led to the aggregation of MC chains. The degree of aggregation of MC chains increased with the rise of temperature.

4.
Carbohydr Polym ; 233: 115859, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32059910

RESUMO

Naked-eye detection pH sensor is becoming a powerful tool in food safety monitoring. In this work, a pH sensor was developed by incorporating cellulose modified with acidochromic dye into polyvinyl alcohol (PVA). The results indicated that the dye (up to 170.4 µmol/g) was successfully anchored to cellulose. It was demonstrated that the addition of acidochromic regenerated cellulose (ARC) resulted in enhancement of tensile strength, elongation at break and maximum decomposition temperature by 44 %, 43.6 % and 11 °C, respectively. The pH sensor demonstrated that a visible color change from yellow to brick-red and to purple when placed in solutions of pH = 7, 10 and 12. The pH sensor showed excellent resistance to leaching under strong acidic and alkaline conditions. When applied to spoiled shrimp, an evident color change from yellow to brown was observed, suggesting it could serve as an easy-to-use, non-destructive visual indicator system for real-time food monitoring.

5.
Int J Biol Macromol ; 147: 18-23, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31917977

RESUMO

Organo-hydrogels are widely used in various fields, due to functional organic ingredients immobilized by the gel network or stored and protected by the gels. Herein, cellulose acetoacetate (CAA) served as reactive natural polymer emulsifier to stabilize thyme oil-in-water (O/W) emulsions. Hydroxypropyl chitosan (HPCS) was added to the continuous phase in emulsions to achieve the organo-hydrogel via the enamine bonds under mild conditions. The thyme@CAA emulsion with different loadings of the inner phase (up to 50%) displayed uniform droplets distribution (3-5 µm) and favorable stability. The organo-hydrogel was systematically analyzed by Fourier transform infrared spectroscopy, optical microscope, rheology analyses. The emulsion droplets evenly dispersed in the three-dimensional network. The modulus of organo-hydrogels depended on the viscosity of precursor emulsions and the crosslinking density. The resulting organo-hydrogel displayed favorable antibacterial activity against E. coli and S. aureus. CAA, as the reactive emulsifier and crosslinking agent, was a promising alternative candidate to fabricate a series of organo-hydrogel.

6.
Int J Biol Macromol ; 148: 811-816, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31962069

RESUMO

Cellulosic colloidal suspensions present unique opportunities for rheological modification of complex fluids. In this work, the rheological behavior of regenerated cellulose (RC) suspensions, including their oscillating shear and time-dependent behavior, as well as yield stress, were studied. The rheological effects of sodium alginate's addition to aqueous RC solutions subject to shear flow were investigated. The results reveal that the RC suspension exhibited "gel-like" behavior and had a shear-thinning property. At increasing RC concentrations, the suspensions' yield stress and the extent of viscosity recovery after plastic deformation had both increased. The viscoelastic suspensions underwent a transition from "solid-like" to "liquid-like" behavior upon sodium alginate's inclusion. Sodium alginate was found to enhance RC suspensions' viscosity recoverability. Furthermore, with increasing concentrations of sodium alginate, the yield stress of RC suspension began to decrease and then vanished, occurring below the 1:1 RC: sodium alginate weight ratio with total solid content fixed at 1 wt%, due to RC's inability to form an extended network RC. This study yields insights into the rheology of RC suspensions and the influence of sodium alginate and supports both their usage as rheological modifies in applications such as coatings, drug delivery systems, and additive manufacturing techniques such as 3D printing.

7.
Int J Biol Macromol ; 148: 627-634, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31968214

RESUMO

Phase change materials (PCMs), widely used in thermal management filed, can store or release thermal energy during phase-changing processes, but the inherent low thermal conductivity and leakage problem restrict their practical applications. Herein, boron nitride nanosheets (BNNSs) doped cellulosic scaffolds (CS) were used as novel support materials to construct shape-stabilized PCM with enhanced thermal conductivity. The composite PCM exhibits excellent shape stability against pressure, tension and bending (90°) even at high loading of the solid-liquid PCM polyethylene glycol (PEG) (95.6 wt%). The resulting composite PCMs have enthalpy capacity (ΔHm/ΔHc) ranged from 165.3 J g-1/169.3 J g-1 to 169.1 J g-1/176.1 J g-1 with stable cycling reliability. Moreover, the thermal conductivity of the composite PCM could increase by 42.8% at a low loading of BNNSs (1.9 wt%), without affecting its electrical insulation properties (over 107 Ω cm). The thermally-conductive shape-stabilized PCM composite prepared by this feasible method have great potential in thermal management of electronics.

8.
Spectrochim Acta A Mol Biomol Spectrosc ; 230: 118051, 2020 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-31958601

RESUMO

Accurate real-time determination of each dye in combination dyeing is critical to the control of dyeing process, which plays an important role in upgrading the dyeing techniques of textile. In this work, Raman spectroscopy was applied to dyeing baths containing multiple dye species of varying structures to quantitatively monitor the dyeing process of each individual dye. Quantitative models were successfully established by partial least squares (PLS) for all combinations of the nine commonly used reactive dyes studied. The correlation coefficients were greater than 0.99, the root mean squared errors of calibration (RMSEC) were less than 0.2650 and the root mean squared errors of prediction (RMSEP) were less than 0.1340, even for the three-component mixture of Reactive Red 239 (RR239), Reactive Yellow 176 (RY176) and Reactive Blue 194 (RB194), which are similar in structures. The model was shown to be valid in the presence of added electrolytes (sodium sulfates). Real-time adsorption monitoring based on the model revealed that the dyes interacted with one another and competed for active sites. The adsorption kinetics obtained by Raman analysis shed light on dye compatibility and could be used to guide the design of dyeing recipe and dyeing process for optimum color reproduction. In addition, in situ monitoring by Raman spectroscopy maybe integrated with real-time on line control of dyeing parameters for fully automated production of dyed fabrics.

9.
Int J Biol Macromol ; 144: 624-631, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31812743

RESUMO

This paper provides a novel and facile method to synthesize antibacterial phase change microcapsules (microPCMs) decorated with silver particles, where lignin was acting as both the Pickering stabilizer and the reducing agent for silver. First lignin Pickering emulsions at various oil-to-water ratios and lignin loading were prepared. Then, n-eicosane encapsulated in polyurea (PU) shells was prepared via interfacial polymerization of isophorone diisocyanate (IPDI) and ethylene diamine/diethylene triamine (EDA/DETA) in a Pickering emulsion stabilized by lignin particles. The results showed that the lignin particles were embedded in the microPCMs shell. These lignin particles were utilized to reduce silver ions, resulting in silver particles decorated microPCMs (Ag/lignin microPCMs). The resulting Ag/lignin microPCMs exhibited a well-defined core-shell spherical morphology with high phase-transition enthalpy (177.6 J/g), high encapsulation efficiency (69.0%) and good thermal durability. As well, the Ag/lignin microPCMs presented good antibacterial activity, showing great potential in industrial applications such as biomedical, textile and construction areas.

10.
Int J Biol Macromol ; 146: 1-8, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31870865

RESUMO

This work explored the use of Pickering emulsion stabilized by lignin nanoparticles (LNPs) to microencapsulate 1-tetradecanol (TDA) via polymerization of acrylates for thermal management. The morphology and thermal performance of the resulting microcapsules were explored using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). A highest encapsulation ratio of 81.4% and melting enthalpy of 190 J/g could be achieved when the core/shell mass ratio was 2:1, and 10 wt% of the crosslinking monomer pentaerythritol tetraacrylate (PETRA) was used. Results of the leakage and accelerated thermal cycling tests showed that the microcapsules had good thermal and chemical stability. When the microcapsules were combined with gypsum, an effective thermal storage composite was obtained, showing good potential for thermal management in the construction field.

11.
Int J Biol Macromol ; 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31751689

RESUMO

Polylactide/cellulose nanocomposites were fabricated by blending of commercial polylactide (PLA) and modified cellulose nanocrystals (CNCs). Modified CNCs were prepared via the in situ polymerization of CNCs and L-lactic acid (CNCs-PLLA) or D-lactic acid (CNCs-PDLA). The actual occurrence of chemical bond between CNCs and PLA segment was confirmed by Fourier transform infrared, nuclear magnetic resonance, X-ray diffraction and solubility tests. Differential scanning calorimetry and X-ray diffraction characterization indicated that CNCs-PDLA better improved the crystallization ability of PLA matrix compared with CNCs-PLLA. Furthermore, compared with the neat PLA (60.0 MPa), the tensile strength of resulting nanocomposites showed an enhancement of up to 36% (81.65 MPa). And the nanocomposites with CNCs-PDLA exhibited both high crystallinity and improved mechanical properties.

12.
Carbohydr Polym ; 224: 115184, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472855

RESUMO

In this paper, we demonstrated an efficient continuous flow reactor packed with nanocellulose sponges made from the sustainable wood pulp. The key component of such reactor, a wood pulp derived nanocellulose sponge loaded with metal catalysts, exhibited high porosity and interconnected porous structure, providing low flow resistance and long-term stability to the flow reactors. The packing material showed good performance in Huisgen cycloaddition in both batch and continuous flow systems. Key comparisons between two systems including reaction kinetics, operating conditions and safety were particularly discussed. Various triazoles have been afforded with >99% conversion, even for gram scale reaction in flow systems. The continuous flow reactors we developed were easily derivatized, thus forming a general, economic and readily scalable platform as promising synthesis tools.

13.
Int J Biol Macromol ; 140: 10-16, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419550

RESUMO

Regenerated chitin (RCh)/poly (lactic acid) (PLA) blends with enhanced properties were successfully prepared via the Pickering emulsion approach. An oil-in-water Pickering emulsion of PLA/dichloromethane (DCM) stabilized with RCh via an ultrasonic homogenizer was formed. A uniformly dispersed blends were obtained upon slow volatilization of DCM. The effects of RCh on physical/morphological, thermal, mechanical and rheology properties of the blends were studied. The introduction of RCh in PLA improved its crystallinity from 23.4% to over 38.0%. The blends displayed an improvement in storage modulus of 393% at 70 °C for 2 wt%RCh as compared with neat PLA. The RCh/PLA blends showed an enhancement in both tensile strength and elongation at break of 18% and 31% respectively at the loading of 1.5 wt%-RCh. Moreover, the complex viscosity of the blends was increased compared to neat PLA, and all the blends exhibited shear-thinning behaviour without any plateau region at low angular frequencies (ω < 10 rad/s). These results suggest that the low weight content RCh introduced to PLA matrix via this facile Pickering emulsion approach not only promotes nucleation in RCh/PLA blends but also acts as a promising reinforcing agent for PLA.

14.
Soft Matter ; 15(37): 7404-7411, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31465077

RESUMO

Herein, a PVA (polyvinyl alcohol)-based multi-responsive hydrogel was prepared by introducing the dynamic and reversible supramolecular complexation between polyvinyl alcohol acetoacetate (PVAA) and Fe3+ ions within 20 s at room temperature. PVAA-Fe hydrogels could be achieved by the simple mixing process of a PVAA aqueous solution with FeCl3 aqueous solution. The soluble PVAA was synthesized by the reaction of PVA with tert-butyl acetoacetate (t-BAA) via transesterification in dimethyl sulfoxide (DMSO). The chemical structure of PVAA was systematically characterized by FT-IR and 1H NMR spectroscopy. The resulting hydrogel showed excellent self-healing behavior without other external stimuli. It was also demonstrated that the PVAA-Fe hydrogel exhibited multi-responsive properties, such as responsiveness to pH, redox, light irradiation and temperature. In addition, the presence of Fe3+ ions and Cl- ions in the gel imparted the PVAA-Fe hydrogel with favorable conductivity. Therefore, the strategy for the facile preparation of the hydrogel in this work could provide a benign and versatile method for achieving multi-functional soft materials for various applications such as smart devices, logic gates, and sensors.

15.
Carbohydr Polym ; 223: 115079, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31427025

RESUMO

Cellulose composites are an important class of polymeric composites due to their renewable, biodegradable feedstock, and tend to have exceptional properties due to peculiar increase of the matrix-filler interface. In this work, a new breed of colloids enabled by regenerated cellulose (RC) was used to prepare polystyrene/cellulose composites. Specifically, an oil-in-water Pickering emulsion of styrene stabilized by RC was prepared, followed by polymerization of styrene, allowing us to obtain a uniformly dispersed PS/RC composite. When the RC concentration was above 0.8 wt%, a network of RC spontaneously formed in the composite, as evidenced by rheological testing. Furthermore, the addition of RC to polystyrene improved the composite's thermal stability and tensile mechanical properties while minimally impacting average visible light transmission (with a decrease in average transmission by about 1-5%). Regenerated cellulose is a promising nanofiller for polymeric composites due to its environment friendly and cost effective nature, and could be used for preparation of other novel RC-reinforced composites.

16.
Int J Biol Macromol ; 137: 197-204, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31255621

RESUMO

The use of nanocellulose is an attractive method to improve the characteristics of biodegradable polymers, but its effects are often affected by uneven dispersion. In this work, cellulose nanocrystals (CNCs) were evenly dispersed into poly(lactic acid) (PLA) via the Pickering emulsion approach. The PLA/CNC composites prepared were studied by rheological, thermal as well as mechanical measurements. Changes in the rheological characteristics of the composites showed that CNC promoted the transition of the composites from fluid to solid-like behavior at high temperatures. The introduction of 5 wt% CNC improved the crystallinity of PLA considerably and increased the onset temperature of crystallization by about 10 °C. The storage modulus of the composites increased throughout the entire temperature range of testing. Flexural modulus was improved considerably. All the results indicated that the Pickering emulsion approach improved the dispersion of CNC in the PLA matrix and CNC improved efficiently most properties of PLA.


Assuntos
Celulose/química , Emulsões , Nanopartículas/química , Poliésteres/química , Varredura Diferencial de Calorimetria , Fenômenos Mecânicos , Reologia , Análise Espectral , Temperatura de Transição
17.
Carbohydr Polym ; 221: 202-208, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31227159

RESUMO

Cotton fabric (CF) is commonly used in wound treatment, however, its hemostatic efficiency is far from sufficient. In this study, modified cotton fabric (MCF-0.39) was obtained by a carboxymethylation process, which endowed MCF-0.39 with good swelling ability and water absorption capacity. Chitosan (CHI) was bound to MCF-0.39 by the binder sodium carboxymethyl cellulose (NaCMC) via flat-screen printing technique to prepare the hybrid hemostatic material (CHI-MCF-0.39). The blood clotting index (BCI) of CHI-MCF-0.39 was 3.15-fold lower than that of CF, demonstrating the good clotting ability of the material. In rat liver injury and femoral artery animal model, the groups using CHI-MCF-0.39 had less hemostasis time and blood loss compared with those groups using CF. All the above results indicate that the prepared CHI-MCF-0.39 has promising future applications as effective hemostatic material in trauma treatment.


Assuntos
Carboximetilcelulose Sódica/farmacologia , Quitosana/farmacologia , Fibra de Algodão , Gossypium/química , Hemostáticos/farmacologia , Curativos Oclusivos , Animais , Coagulação Sanguínea/efeitos dos fármacos , Carboximetilcelulose Sódica/química , Quitosana/química , Artéria Femoral/lesões , Hemostáticos/química , Fígado/lesões , Coelhos , Ratos Sprague-Dawley
18.
Carbohydr Polym ; 213: 184-191, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30879659

RESUMO

Various metal-organic frameworks (MOF) are highly effective catalysts for detoxifying chemical warfare agents (CWAs). In this study, we reported a MOF-loaded cellulose sponge for fast degradation of CWAs simulant. In situ growth of UiO-66-NH2 onto γ-Glycidoxypropyltrimethoxysilane (GPTMS) modified cellulose sponge was achieved. This sponge featured high porosity (88%), high specific surface area (310.5 g/m2) and low density (36 mg/cm3). The UiO-66-NH2 functionalized cellulose sponge showed excellent catalytic activity for detoxifying 4-Nitrophenyl Phosphate (DMNP) and the half-life was as short as 9 min.

19.
Carbohydr Polym ; 211: 173-180, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824077

RESUMO

Herein, the acetoacetyl group was directly anchored on the surface of cotton fabric (Cotton-acac) via heterogeneous transesterification. This surface modification strategy was systematically characterized by Fourier transform infrared spectroscopy, solid-state 13C nuclear magnetic resonance spectroscopy, X-ray diffraction, and thermogravimetric analysis, which confirmed it was a mild and efficient process. Besides, Cotton-acac was used as the versatile intermediate post-modified with gentamicin (Gen) and octadecyl amine (ODA) molecules to impart cotton fabric dual functions with hydrophobic and antibacterial properties. The resulting cotton fabric showed dual and outstanding hydrophobic and antibacterial performance against E. coli and S. aureus, with the bactericidal rates of over 99.99% and the water contact angle of 145°even after 10 cycles of standard washing. Therefore, the heterogeneous modification provided a benign and versatile method for regulating the interfacial properties of the cellulosic materials, with the possibility of post modification for various applications through the acetoacetyl chemistry.


Assuntos
Aminas/química , Antibacterianos/química , Fibra de Algodão , Gentamicinas/química , Têxteis , Acetoacetatos/química , Escherichia coli/crescimento & desenvolvimento , Interações Hidrofóbicas e Hidrofílicas , Staphylococcus aureus/crescimento & desenvolvimento
20.
Carbohydr Polym ; 209: 223-229, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30732803

RESUMO

The Biginelli multicomponent reaction has been used as an effective and model method to efficiently prepare a library of cellulose derivatives based on cellulose acetoacetate (CAA). Various cellulose derivatives containing 3, 4-dihydropyrimidin-2(1 H)-ones (DHPMs) with different functional groups (carboxyl, methoxyl, and nitro) are synthesized. The entire reaction process is followed using FT-IR, 1H NMR. The results demonstrate that more than 80% of the acetoacetyl groups are converted within four hours. Additionally, all the cellulose derivatives are confirmed to have favorable thermostability and good solubility in selected solvents. Furthermore, polymers (in this case, poly (ethylene glycol) monomethyl ether (mPEG)) can also be anchored to the cellulose backbone via this facile modular approach. Therefore, the Biginelli multicomponent reaction offers a straightforward method for diverse and large-scale cellulose derivatization. These results are expected to prompt broader study of this multicomponent reaction in interdisciplinary fields.

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