Cellulose Acetate Butyrate Research Articles

Improved catalytic stability of immobilized Candida antarctica lipase B on macroporous resin with organic polymer coating for biodiesel production.

Lipase is one of the most widely studied and applied biocatalysts. Due to the high enzyme leakage rate of the immobilization method of physical adsorption, we propose a new lipase immobilization method, based on the combination of macroporous resin adsorption and organic polymer coating. The immobilized Candida antarctica lipase B (CALB@resin-CAB) was prepared by combining the macroporous resin adsorption with cellulose acetate butyrate coating, and its structure was characterized by various analytic methods. Immobilized lipase was applied for biodiesel production using acidified palm oil as the starting material, the conversion rate achieved as high as 98.5% in two steps. Furthermore, the immobilized lipase displayed satisfactory stability and reusability in biodiesel production. When the aforementioned reaction was carried out in a continuous flow packed bed system, the yield of biodiesel was 94.8% and space-time yield was 2.88g/(mL∙h). The immobilized lipase CALB@resin-CAB showed high catalytic activity and stability, which has good potential for industrial application in the field of oil processing.

Moxifloxacin HCl -loaded Cellulose Acetate Butylate In Situ Forming Gel for Periodontitis Treatment.

Periodontitis presents significant treatment challenges due to its complexity and potential complications. In response, an in situ forming gel (ISG) loaded with moxifloxacin HCl (Mx) and cellulose acetate butyrate (CAB) was developed for targeted periodontitis therapy. Mx-loaded 10-45% CAB-based ISGs were developed, and their physicochemical properties such as rheology, viscosity, contact angle, gel morphology and gel formation, interface interaction were investigated. Moreover, the formulation performance studies including drug release and kinetics, in vitro degradation, and antimicrobial activities were also evaluated. The Mx-loaded ISGs containing 25-45% CAB demonstrated rapid matrix formation in both macroscopic and microscopic examinations and presented plastic deformation matrix. Tracking with sodium fluorescein and Nile red fluorescence probes indicated delayed solvent movement owing to CAB matrix formation. Adequate CAB content sustained Mx release for one week, following Peppas-Sahlin model and indicating a predominantly Fickian diffusion mechanism. Higher CAB content likely contributed to a denser matrix structure, leading to a slower in vitro degradation rate. Synchrotron radiation X-ray tomographic and SEM imaging provided insights into the CAB matrix structure and porous network formation. These ISG formulations effectively inhibited Staphylococcus aureus, Escherichia coli, Candida albicans, and Porphyromonas gingivalis. The Mx-loaded 40% CAB-based ISG shows promise as a dosage form for treating periodontitis. Further clinical trials are necessary to ensure the safety of this new ISG formulation, despite existing safety data for other medicinal uses of CAB. HIGHLIGHTS: Moxifloxacin HCl-loaded 10-45% cellulose acetate butyrate (CAB)-based in situ forming gels (ISG) were developed. They were evaluated for physicochemical properties, drug release, in vitro degradation, and antimicrobial activities. ISGs with 25-45% CAB showed swift matrix formation and plastic deformation Adequate CAB content sustained Mx release with Fickian diffusion mechanism They promise for periodontitis treatment because of effective inhibition of related pathogens.

Microencapsulation of <i>Chromolaena odorata</i> Leaf Extract with Cellulose Esters for the Application as an Eco-Friendly Antibacterial Agent

The aim of this work is to develop an eco-friendly antibacterial agent in the form of microcapsules containing extract from Chromolaena odorata leaves using the solvent evaporation method. The wall materials for encapsulating were tested with various cellulose esters including cellulose acetate (CA), cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP). The evaluation of microcapsules containing C. odorata leaf extract was focused on their encapsulation efficiency, size, shape, thermal stability, and antimicrobial activities. The results showed that CAB was a suitable wall material for the encapsulation of C. odorata leaf extract. The CAB microcapsules exhibited the highest encapsulation efficiency, which was 65.82 ± 3.07. The size of CAB microcapsules was the smallest, at 1013.3 ± 66.5 nm. According to the thermogravimetric analysis, the prepared microcapsules were able to protect the extract of C. odorata leaves from the environment. Moreover, the CAB microcapsules containing C. odorata leaf extract showed the best antibacterial activities against Escherichia coli ATCC 25922 and Stapphylococcus aureus ATCC 25923. The minimum bactericidal concentration of the microcapsules was 25.6 mg/mL in both bacteria. This study proved the potential application of C. odorata leaf extract as a biomaterial in diverse industries in the future.

Design and Characterization of Printed Flexible Humidity Sensor

The development of humidity sensors is essential for applications in the environmental, agriculture, medical and semiconductor industries [1-2]. The basic mechanism of humidity sensors is explained by a Grotthuss chain reaction, which is usually simplified as a proton-hopping process [3]. This refers to a dynamic charge transfer process at a certain relative humidity (RH). The humidity sensors can be of different types such as capacitive type, resistive, colorimetric and surface acoustic wave [4-7]. Capacitive type sensors are linear, require less complex circuitry and can operate for a wide range of humidity [8]. A typical capacitive type humidity sensor uses hydrophilic films as sensing layers which are stable at higher humidity levels [9]. Polymers that are being used for the fabrication of capacitive type humidity sensors include poly (2-hydroxyethyl methacrylate) (pHEMA) [9], cellulose acetate butyrate (CAB) [10], polyimide [11] and polymethyl methacrylate (PMMA) [12]. In this work, a humidity sensor has been fabricated on glass and flexible substrates.The design of humidity sensor consists of printed pattern of a conductor such as silver and a spin coated dielectric such as polymer poly (2-hydroxyethyl methacrylate) (p-HEMA) and polyimide. The printing of conductor was done in an interdigitated pattern as shown in figure 1. The thickness of sensitive materials was controlled by varying the spin time from 10 to 30 seconds. A thick solution of sensitive materials was prepared by adding a 3 gm of polymer in 50 mL ethanol in the case of p-HEMA. Currently we are preparing one more set of samples using polyimide and we will present a comparison of two humidity sensors- one with p-HEMA and another with polyimide. A humidity sensor that employs interdigitated capacitors (IDC) printed with silver on a glass and flexible substrate was successfully fabricated using p-HEMA and polyimide at spin speed of 2000 rpm for 20 seconds. Our goal is to integrate the humidity sensor into a robotic arm to perform real-time object characterization in agricultural applications via comprehensive understanding of the operations of harvesting robots in various crop types and environmental conditions.

Synthesis of Cellulose Acetate Butyrate Microspheres as Precursor for Hard Carbon-Based Electrodes in Symmetric Supercapacitors.

Cellulose microspheres have a wide range of applications due to their unique properties and versatility. Various preparation methods have been explored to tailor these microspheres for specific applications. Among these methods, the acetate method using cellulose acetate is well known. However, replacement of the acetate group through the butyrate group significantly extends the variety of morphological properties. In the present work, microspheres based on cellulose acetate butyrate are being developed with modified characteristics in terms of particle size, porosity, surface morphology and the inner structure of the microspheres. While the inner structure of cellulose acetate microspheres is predominantly porous, microspheres prepared from cellulose acetate butyrate are mainly filled or contain several smaller microspheres. Carbon materials from cellulose acetate butyrate microspheres exhibit a high specific surface area of 567 m2 g-1, even without further activation. Activation processes can further increase the specific surface area, accompanied by an adaptation of the pore structure. The prepared carbons show promising results in symmetrical supercapacitors with aqueous 6 M KOH electrolytes. Activated carbons derived from cellulose acetate butyrate microspheres demonstrate an energy density of 12 Wh kg-1 at a power density of 0.9 kW kg-1.

Effect of cellulose derivatives on crystallization and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Abstract In this work, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was modified by cellulose derivatives, and the effects of different kinds of cellulose derivatives on the crystallization and mechanical properties of PHBV were investigated. The crystallization and mechanical properties of PHBV/cellulose derivatives composites were measured by means of differential scanning calorimeter, polarizing microscope, and mechanical properties testing instruments. Studies show that cellulose acetate (CA) can promote the crystallization of PHBV, a small amount of CA can significantly increase the crystallization temperature of PHBV. The crystallization rate of PHBV was also accelerated by CA. However, the addition of cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) decreased the crystallization temperature of PHBV and inhibited the nucleation of PHBV. And the degree of inhibition increased with the increase of CAB and CAP content. CAB and CAP have good compatibility with PHBV, CAB, and CAP can be uniformly dispersed in PHBV. Cellulose derivatives with specific component content can enhance the tensile properties of PHBV without losing the impact strength.

Synthesis and luminescent properties of cellulose acetate butyrate films doped with europium complex Eu(TTA)3 for optical thermometry

In this work, the luminescent β-diketonate europium complex, Eu(TTA)3, was incorporated into the polymer cellulose acetate butyrate in different concentrations in the form of composite films. The photoluminescence analysis showed that the composites improved the internal transition of the europium ion, 5D0 → 7F2, mainly responsible for the emission of red light from the complex, by providing a highly asymmetric chemical environment around the europium ion and by reducing non-radiative decays. The composite matrix also contributed to the quantum efficiency of the luminescence, reaching 38 %, by reducing the excited state deactivation rates. The luminescence lifetime of the composite linearly decayed with increasing temperature, while the luminescence intensity displayed an exponential decrease by increasing temperature, both behaviors proved to be appropriate for use in optical thermometry. The analysis of Raman spectra, Judd-Ofelt parameters, decay rates, and lifetime showed that the characteristics of the isolated complex were mostly maintained after being added to the polymeric matrix.

Blend Cellulose Acetate Butyrate Membrane with Molecular Weight 12,000, 30,000 and 65,000 for CO2/N2 Separation

The demand for energy has been increasing gradually due to the rapid growth of the global economy. The emission of greenhouses gases (GHGs) especially, carbon dioxide (CO2), which is a major greenhouse gas, has contributed to the global warming issue. Therefore, to reduce emissions and eliminate the serious consequences, membrane separation technology was introduced as an alternative option that has high CO2 separation efficiency. It requires lower energy consumption, lower capital costs and it is commercial and environmentally friendly. Most importantly, it is easy to operate. In this study, the blend cellulose acetate butyrate (CAB) membrane was synthesised from the CAB polymers using the wet-phase inversion method with molecular weights of 12,000:30,000:65,000 in the ratio of 1:2:2, respectively. The blend CAB membrane casted at 250 μm (M2) was the best performing membrane among all the membranes due to its relatively high CO2 gas permeance and the highest CO2/N2 selectivity, which were 7,560.80 ± 20 GPU and 1.5319 ± 0.05, respectively. The fabricated CAB membrane was then characterised by using the Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and surface contact angle. It showed strong stretching bands around 1,044.07 cm−1, 1,226.25 cm−1 and 1,744.04 cm−1, which indicated a single bond C-O and carboxyl group (C=O). The higher the hydrophobicity of the membrane, the stronger the affinity for CO2 molecules. In this case, the contact angle of the membrane casted at 150 μm (M1) was 120.460, which was the highest. This newly synthesised CAB membrane is expected to benefit major industries by its cost effective and high energy saving properties. Most importantly, the gas separation efficiencies are better than the current technologies.

Preparation, characterization and decomposition test on Tapanuli organoclay reinforced cellulose acetate/cellulose acetate butyrate blend composites

The need for biodegradable composites has increased for many applications in recent years. Cellulose acetate (CA) and cellulose acetate butyrate (CAB) are relatively easy and cheap to fabricate, as well as relatively easy to decompose compared to other polymers. These materials are transparent and lightweight with low tensile properties. In this current study, the effect of Tapanuli clay addition on tensile and decomposition properties of CA and CA–CAB systems were investigated. Tapanuli organoclay was prepared by a cation exchange treatment using hexadecyltrimethylammonium bromide (HDTMA-Br) surfactant to Na-bentonite. Prior to the treatment, the Tapanuli clay was subjected to purification from organic and carbonate compounds and to balance the cations by homogenizing them into Na+. The basal spacing of Tapanuli clay increased from 1.52 nm up to 1.98 nm. CA and CA −5 wt% CAB composites were then synthesized using a solvent casting method. It was found that the addition of both 5 wt% CAB and 7 wt% organoclay in CA decreased the tensile strength and reduced the mass loss by 70%. After 45 days of the decomposition test, it was indicated that the presence of 5 wt% CAB in CA reduced the mass loss of the system by about 50%. These findings were con-firmed by the Scanning Electron Microscope (SEM) images which showed different patterns of as-synthesized and decomposed materials. In conclusion, the presence of 1 wt% Tapanuli organoclay slightly increased the decomposed mass of CA film and enhanced the tensile strength of CA-co-CAB.

Design and evaluation of a kind of polymer-bonded explosives with improved mechanical sensitivity and thermal properties

The emergence of TKX-50, an energetic ionic salt with a high enthalpy of formation and low sensitivity, has opened a new path for the development of high-energetic, insensitive composite explosives. However, due to the poor interfacial binding properties of TKX-50 with conventional binders, there is a lack of effective guidance for the design of TKX-50 based composite explosives. To address the above issues, the interactions between carboxymethyl cellulose acetate butyrate (CMCAB) and other binders with explosives TKX-50/HMX were compared using the molecular dynamics method. Based on the simulations, TKX-50/HMX/CMCAB-based polymer-bonded explosives (PBXs) were prepared with CMCAB as binder, which displays a high binding energy (Ebind) with TKX-50 and high cohesive energy density (CED), and the effect of TKX-50 content on the performance of PBXs was investigated. The physical properties of PBXs, specifically the morphology, mechanical sensitivity, and thermal conductivity, were analyzed by SEM, sensitivity apparatus, and thermal conductivity meter, respectively. The specific heat capacity (Cp) and non-isothermal decomposition temperature of PBXs were tested by DSC, and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety. The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument. The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions. The computer code EXPLO5 was used to predict the detonation parameters of PBXs. The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties, and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile. The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX. This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.

Design of Sustainable Aluminium-Based Feedstocks for Composite Extrusion Modelling (CEM).

Additive manufacturing (AM) has become one of the most promising manufacturing techniques in recent years due to the geometric design freedom that this technology offers. The main objective of this study is to explore Composite Extrusion Modelling (CEM) with aluminium as an alternative processing route for aluminium alloys. This process allows for working with pellets that are deposited directly, layer by layer. The aim of the technique is to obtain aluminium alloy samples for industrial applications with high precision, without defects, and which are processed in an environmentally friendly manner. For this purpose, an initial and preliminary study using powder injection moulding (PIM), necessary for the production of samples, has been carried out. The first challenge was the design of a sustainable aluminium-based feedstock. The powder injection moulding technique was used as a first approach to optimise the properties of the feedstock through a combination of water-soluble polymer, polyethyleneglycol (PEG), and cellulose acetate butyrate (CAB) wich produces low CO2 emissions. To do this, a microstructural characterisation was carried out and the critical solid loading and rheological properties of the feedstocks were studied. Furthermore, the debinding conditions and sintering parameters were adjusted in order to obtain samples with the required density for the following processes and with high geometrical accuracy. In the same way, the printing parameters were optimised for proper material deposition.

Oleo‐Dispersions of Electrospun Cellulose Acetate Butyrate Nanostructures: Toward Renewable Semisolid Lubricants

AbstractIn this work, the electrospinnability of cellulose acetate butyrate (CAb) solutions, and the ability of the resulting micro‐ and nano‐architectures to structure castor oil are studied aiming to develop eco‐friendly lubricating greases. Particles, beaded‐fibers, defect‐free fibers, and porous nanostructures are successfully prepared by dissolving CAb in N,N‐dimethylacetamide/acetone (DMAc:Ac, 1:2 w/w) and methylene chloride/acetone (DM:Ac, 1:1 w/w) solvent mixtures at different concentrations (2.5–15 wt.%). The formation of bead‐free nanofibers is favored at concentration above 10 wt.%, when solutions achieve relaxation times of ≈50 ms and shear‐thinning in extensional and shear flow tests, respectively. Non‐porous and porous CAb nanostructures are successfully used as castor oil thickeners at concentrations of 3–5 wt.%, leading a wide variety of rheological responses which mimic those of traditional semisolid lubricants. The surface properties of the nanofibers have a significant impact on the wear and friction performance in metal–metal contact, which has been associated with the oil release ability of the generated 3D network. Oleo‐dispersions prepared with smooth fibers show tribological performance comparable to, or even better than, commercial lithium greases. Overall, this study reveals the potential of CAb electrospun nanostructures for the development of next‐generation renewable semisolid lubricant formulations.

DNA Adsorption Capabilities of Amine Functionalized Magnetic Cellulose Acetate Butyrate Beads from Aqueous Solution

AbstractIn this work, the magnetic cellulose acetate butyrate beads (mCABs) were prepared and then, their surfaces were modified with [(3‐Aminopropyl) triethoxysilane)] (APTES) solution to generate amine groups (−NH2) as a ligand for DNA adsorption in the aqueous solution. After the surface modification, the −NH2 functionalized mCABs (N−mCABs) were characterized with Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscope (SEM), and energy dispersive X‐ray (EDX) analysis. The optimum pH value of DNA adsorption was observed at pH 4 and at this point, the N−mCABs adsorbed 4.27 mg/g DNA at room temperature (RT). The maximum adsorbed amount of DNA was calculated as 5.24 mg/g and the DNA adsorption was exothermic; furthermore, DNA adsorption was monolayer and the Langmuir adsorption model was more fitted than the Freunclich isotherm model due to the regression coefficient (R2), and the qmax values of the Langmuir model. According to reusability studies, the prepared adsorbent protected its stability and the adsorption capacity after the 5 consecutive adsorption, desorption, and regeneration cycles.

Preparation and in-vitro evaluation of single and bi-layered beeswax-based microparticles for colon-specific delivery of mesalamine

Beeswax is selected as a natural coating material for the development of new colon specific drug delivery systems charged by mesalamine. In a first step, beeswax microparticles are prepared using hot-melt process of microencapsulation where drug:beeswax ratio, stirring speed, emulsifier concentration and pH of external phase are varied for the optimization of the drug entrapment and microparticles? morphology. The effect of the nature of the emulsifier is also discussed by studying the hydrophilic?lipophilic balance (HLB) value. In a second step, to obtain delayed delivery systems, bi-layered microspheres are elaborated by the process of emulsion?solvent evaporation using ethylcellulose or cellulose acetate butyrate as outer enteric coating layer. All formulations are characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and optical microscopy. The drug release is established in simulated gastric, small bowel and colon liquids and the release mechanism is discussed by applying the Korsmeyer?Peppas model.

Novel enrichment in biobased monomers of waterborne polyurethane dispersions as a textile finishing agent for poly-cotton fabrics

This study introduces a novel biobased textile finishing agent synthesized as waterborne polyurethane dispersions (FCCB-WPUDs), utilizing bio-based monomers like fenugreek oil-based polyol, corn oil-derived emulsifier, and cellulose acetate butyrate (CAB) chain extender. The FCCB-WPUDs were prepared through the prepolymer polymerization method and characterized using FTIR, TGA, DMA, SEM, DLS, and swelling tests. Their application to poly-cotton fabrics significantly improved various fabric properties. The enhancements included increased washing fastness (from 3/4 ± 0.01 to 4 ± 0.02 for dyed and 3 ± 0.02 to 4/5 ± 0.02 for printed fabrics), rubbing fastness (from 3 ± 0.02 to 4/5 ± 0.03 for dyed and 4 ± 0.02 to 4/5 ± 0.03 for printed fabrics), and perspiration fastness (from 3 ± 0.02 to 4 ± 0.03 for acidic dyed and 3/4 ± 0.02 to 4 ± 0.02 for alkaline printed fabrics). Additionally, tear strengths improved significantly (from 13.66 ± 0.04 N/m to 20.53 ± 0.06 N/m for warp dyed and 10.85 ± 0.06 N/m to 15.14 ± 0.06 N/m for warp printed fabrics), along with tensile strengths (from 327 ± 5.38 N/m to 361 ± 3.26 N/m for warp dyed and 357 ± 5.34 N/m to 449 ± 4.90 N/m for warp printed fabrics). These improvements correlated with increasing CAB moles as a chain extender. This research presents a cost-effective and simple biobased method for textile finishing, offering an alternative to petrochemical-based monomers in conventional WPUD preparation.

A Highly fluorescent vinylene-linked covalent organic framework for chemical sensing of pH and NH3 gas with wide dynamic range

Herein, a vinylene-linked covalent organic framework (TMT-BPDA-COF) was prepared via the Aldol condensation of 2,4,6-trimethyl-1,3,5-triazine (TMT) and 4,4'-biphenyl dimethyl formaldehyde (BPDA). TMT-BPDA-COF displayed high crystallinity and thermal stability, and robust chemical stability in strong acid, strong base and common organic solvents. TMT-BPDA-COF nanosheets emitted strong yellow fluorescence with the quantum yield of 14.9% and showed fast reversible response toward pH with a wide range (pH 0.0 ∼ 14.0) based on the intramolecular charge transfer effect. Furthermore, portable fluorescent sensors were prepared by incorporated TMT-BPDA-COF nanosheets into agarose gel and cellulose acetate butyrate (CAB), respectively. TMT-BPDA-COF gel showed a wide pH response range over pH 0.0 ∼ 14.0 with a linear range of pH 4.0 ∼ 14.0. TMT-BPDA-COF CAB film exhibited high sensitivity for sensing of NH3 gas with a limit of detection of 1.6 ppb. TMT-BPDA-COF agarose gel and CAB film also exhibited good reversibility and reproducibility in response to pH and NH3 gas, respectively. We expect TMT-BPDA-COF-based sensors, which feature fast response, high sensitivity, wide response range, good reproducibility and reversibility, can apply to detect pH and NH3 gas in the field of environment and industry.

Preparation of bio-based heat storage microcapsules of cellulose acetate butyrate/ polymethylmethacrylate composite by micro-suspension polymerization

ABSTRACT Because of environmental concerns, the utilization of bio-based, renewable resource materials has attracted great attention for a wide range of applications. In this research, green cellulose-based microcapsules containing capric acid (CA) as a bio-heat storage material were prepared. Cellulose acetate butyrate (CAB)/methacrylate polymer composite particles were produced by microsuspension iodine transfer polymerization to encapsulate CA. The influences of methacrylate polymer type and amount on microcapsule morphology, encapsulation efficiency (EE) and thermal properties were investigated. Using methyl methacrylate (MMA) monomer, the colloidal stable spherical microcapsules with smooth surfaces and core-shell morphology were obtained. Although high percentages of EE, ≥70%, were obtained at all CAB:MMA weight ratios, the latent heats of the encapsulated CA were lower than those of the original ones which may be due to the incomplete phase separation of the CAB/PMMA shell and CA core. The increase of CA content up to 60% provided stable spherical microcapsules with a maximum loading of 59% and 97% EE. After thermal cycling for 100 cycles, stable microcapsules still remained with stable thermal properties. The obtained bio-based microcapsules would be well applied for heat storage and temperature control applications.

Microencapsulation of moringa oil in bio-polymer by simple solvent evaporation technique

Moringa oil (MO) contains various bioactive components and pharmacology. It is attractive to use as a raw ingredient in various products. However, there are limitations on its direct utilization, especially MO's instability and hastening the active ingredient's degradation from external environmental factors, including temperature, humidity, oxidation, light, and heat. To solve these problems, in this work, microencapsulation of MO using different biopolymers as cellulose acetate butyrate (CAB), ethyl cellulose (EC), and poly(L-lactic acid) (PLLA) were carried out by a simple solvent evaporation technique. The prepared polymer microcapsule suspensions were highly colloidal stable for all types of biopolymers and ratios. The spherical biopolymer capsules were formed to a micrometer size after solvent evaporation under all conditions. However, when the microcapsules were dried, aggregation was found with the polymer microcapsules at a ratio of PLLA to MO of 50:50 for all three types of polymers, possibly due to the low amount of polymer to completely encapsulate all of MO. When polymer contents increased to 70%, the dried spherical polymer microcapsules were smoothly produced. Using 70% polymers, the PLLA microcapsule surface was smoother than the polymer microcapsules prepared by CAB and EC which exhibited the dent or hole on the outer surface. Micrometer size, spherical polymer capsules with a core-shell morphology were fabricated. Due to the higher hydrophilicity of the polymer than the MO, the polymer moves outward, forming a strong shell around the MO. Then, all three biopolymers can be used for the microencapsulation of MO at a suitable polymer to MO ratio. However, using PLLA at a ratio of PLLA to MO of 70:30 presented the highest encapsulation efficiency (74.08%), which may be due to its high molecular weight. Because of the non-toxicity and biodegradability of biopolymers, the fabricated microcapsules would be well applied in cosmetic products.

Supercapacitors with Gold Colloids That Are Placed at a Short Distance from Active-Carbon Electrodes; The Case for a Plasmonic Effect at the Electrolyte/Electrode Interface

Supercapacitors (S-C) are fast charge/discharge elements. These short-term energy storage found many applications; among which are, powering electronic devices, boosters of fast charging batteries and possibly, as buffers between highly fluctuating sustainable sources and the rather stable electrical grid. For double-layer S-C, one takes advantage of the very narrow interface between an electrolyte and a conductive porous electrode. In contrast, ordinary capacitors are made of a relatively thicker dielectric material, sandwiched between two electrodes.In the past, polarity increase in capacitors was achieved by dispersing conductive colloids in the entire volume of the dielectric material. This approach was primarily used for microwave and optical devices – a field known as plasmonics. For S-C it means that the conductive colloids should be dispersed within the double-layer region, or fairly close to it. The impact of such an approach on the low frequency supercapacitors is not fully yet known. In order to maintain a full polarization effect (as opposed to simply increasing the electrode conductivity), we kept the AuNP at a short distance from the electrode. This is achieved by coating the colloids with a negatively charged ligand - the same approach used to keep a colloidal suspension intact.Here we explore the addition of nano-size Au particles (AuNP) to active-carbon electrodes to find a large amplification in the specific capacitance. For example, C-V data at a scan rate of 20 mV/s indicated a specific capacitance amplification of more than 10 (!) (with respect to a reference sample without the colloids) when 30 micro-g of AuNPs were incorporated with 200 milli-g of active carbon while using a 1 M Na2SO4 electrolyte and a 5% cellulose acetate butyrate binder. These experiments were corroborated by simulations: the Au colloids are indeed to be placed at close proximity but not in contact with the electrodes.

Pad printing inks based on reduced graphene oxide and various cellulose binders: Rheological properties, printability and application in electrochemical sensors

AbstractPad printing is not a widely used printing technique, but it offers the possibility of a simple, fast, and low‐cost production of various high‐resolution electrode structures. Here, the pad‐printed reduced graphene oxide (rGO) electrodes are prepared from pad‐printable inks containing rGO powder and different concentrations of two cellulose‐based polymers: ethylcellulose and cellulose acetate butyrate. The applicability of rGO inks for pad printing is analyzed according to their rheological parameters and printability. Based on viscosity, storage (G′) and loss modulus (G″) values, 10 wt% of ethylcellulose and 15 wt% of cellulose acetate butyrate appear to be most suitable for pad printing. The effect of polymer concentration on rGO electrodes homogeneity and mechanical stability is also evaluated. Cyclic voltammetry measurements for [Fe(CN)6]3−/4− redox system are performed with rGO/cellulose inks pad‐printed onto transparent conductive oxide substrates with the best results when using ethylcellulose as a binder. Finally, the square‐wave voltammetric method assesses the viability of rGO electrodes for the fast detection of ascorbic acid (detection limit of 15 μM) coupled with satisfactory precision (4.5%, n = 5) and long‐term stability during electrochemical measurements.