Acid Composite Films Research Articles

Plasma-Assisted Synthesis of Multicomponent Nanoparticles Containing Carbon, Tungsten Carbide and Silver as Multifunctional Filler for Polylactic Acid Composite Films.

Multicomponent nanoparticles containing carbon, tungsten carbide and silver (carbon-WC-Ag nanoparticles) were simply synthesized via in-liquid electrical discharge plasma, the so-called solution plasma process, by using tungsten electrodes immersed in palm oil containing droplets of AgNO3 solution as carbon and silver precursors, respectively. The atomic ratio of carbon:W:Ag in carbon-WC-Ag nanoparticles was 20:1:3. FE-SEM images revealed that the synthesized carbon-WC-Ag nanoparticles with particle sizes in the range of 20–400 nm had a spherical shape with a bumpy surface. TEM images of carbon-WC-Ag nanoparticles showed that tungsten carbide nanoparticles (WCNPs) and silver nanoparticles (AgNPs) with average particle sizes of 3.46 nm and 72.74 nm, respectively, were dispersed in amorphous carbon. The carbon-WC-Ag nanoparticles were used as multifunctional fillers for the preparation of polylactic acid (PLA) composite films, i.e., PLA/carbon-WC-Ag, by solution casting. Interestingly, the coexistence of WCNPs and AgNPs in carbon-WC-Ag nanoparticles provided a benefit for the co-nucleation ability of WCNPs and AgNPs, resulting in enhanced crystallization of PLA, as evidenced by the reduction in the cold crystallization temperature of PLA. At the low content of 1.23 wt% carbon-WC-Ag nanoparticles, the Young’s modulus and tensile strength of PLA/carbon-WC-Ag composite films were increased to 25.12% and 46.08%, respectively. Moreover, the PLA/carbon-WC-Ag composite films possessed antibacterial activities.

On the bacteriostatic activity of hyaluronic acid composite films

Biofilm-related infections and contamination of biomaterials are major problems in the clinic. These contaminations are frequently caused by Staphylococcus aureus and are a pressing issue for implantable devices, catheters, contact lenses, prostheses, and wound dressings. Strategies to decrease contamination and biofilm related infections are vital for the success of implantable biomaterials. In this context, hyaluronic acid (HA), a naturally derived carbohydrate polymer, known to be biocompatible, degradable, and immunomodulatory, has shown some antimicrobial activity effects. Due to its poor structural stability, crosslinking strategies, and the incorporation of reinforcing fibres in HA gels is required to produce tailored gels for varying applications. Whilst carbon-based reinforcing materials, such as carbon nanofibers (CNF), present some intrinsic antimicrobial activity related to their high surface area, herein, a crosslinking strategy to enhance the mechanical properties and regulate the rate of degradation of HA is presented. We utilise bis-(β-isocyanatoethyl) disulphide (BIED) as the crosslinker with the gel reinforced using 0.25 wt% CNF. The effects of CNF and BIED on the structural, mechanical, thermal, and swelling behaviour are examined. These new HA derivatives exhibit excellent mechanical properties and are capable of withstanding physiological stresses in vivo. Antimicrobial activity of the HA derivatives were tested against Staphylococcus aureus and the results reveal antibacterial effect. These carbohydrate based materials have potential application on surfaces within clinical settings where staphylococcal contamination is currently an issue.

Frequency Based Control of Antifouling Properties Using Graphene Nanoplatelet/Poly(Lactic-co-Glycolic Acid) Composite Films

ABSTRACT In this work, we report an approach to fabricate graphite nanoplatelets/poly(lactic-co-glycolic acid) composite films via drop casting. We tested their frequency-based control of antifouling properties on Escherichia coli bacteria TG1 strain (E. coli TG1), in the safe range of 5 MHz < f < 15 MHz. Scanning electron microscopy (SEM) showed that the average thickness of the composite coatings was 3.5 µm. Raman spectroscopy verified that the structure of the graphene flakes was conserved in the final nanocomposite. Bactericidal assessment was performed by measuring the optical density at 600 nm and the colony forming units (CFU). Our findings showed improved bacteria inhibition when exposed to alternating current frequencies (ACF) at 10 and 15 MHz. At these frequencies, bacteria had also suffered important damage, which was observed by SEM. Culture dynamics after 12 h of the frequency treatments exhibits a significant difference, associated to cell damage observed on bacteria subjected to a specific frequency. The anti-biofilm properties of alternating current frequency (ACV) stimulated GrFs/PLGA thin films underline the importance of the fabrication of novel nanocomposites for biomedical applications where biofilm proliferation is undesirable. Abbreviations: GrFs: graphite nanoplatelets; PLGA: poly(lactic-co-glycolic acid), E. Coli: Escherichia coli; CFU: colony forming units; PEF: Pulsed Electric Field; OD: optical density; ES: electric stimulation; BC: bacteria control; BVF: variable frequency (BVF) treatments; ACVF: alternating current with variable frequency; EPS: extracellular polymeric substances; DMF: N,N-dimethylformamide; THF: tetrahydrofuran; ACF: alternating current frequencies; SEM: Scanning Electron Microscopy; TEM: Transmission Electron Microscopy.

Electrospinning preparation of perylene-bisimide-functionalized graphene/polylactic acid shape-memory films with excellent mechanical and thermal properties

Electrospinning preparation of perylene-bisimide-functionalized graphene/polylactic acid composite films with shape-memory properties.

내부에 폴리아크릴로니트릴 도전섬유가 배열되어 있는 폴리(L-락트산) 복합 필름의 제조와 전자파 차폐 특성

내부에 폴리아크릴로니트릴 도전섬유가 배열되어 있는 폴리(L-락트산) 복합 필름의 제조와 전자파 차폐 특성

Two-in-one integrated sulfur cathode with multifunctional multiwalled carbon nanotube/polyacrylic acid film for high -performance lithium sulfur batteries

Lithium sulfur (Li-S) batteries with high energy density are the promising candidates for the new generation energy storage devices. However, the application of Li-S batteries has been hindered by the poor conductivity of sulfur, polysulfides diffusion, and unsatisfactory practical gravimetric energy density. Herein, the lightweight multiwalled carbon nanotube/polyacrylic acid (MWCNT/PAA) composite film was developed, which could combine functions of the current collector and conductive interlayer into one composite film, to realize the integrated sulfur cathode with successful sufficient electron transport and strong polysulfides adsorption. As a result, the cathode could deliver not only improved cycle performance but also a higher discharging capacity based on the total electrode mass, demonstrating the promising application of the two-in-one integrated sulfur cathode in high-performance Li-S batteries.

All-fiber humidity sensor based on Michelson interferometer with hyaluronic acid and polyvinyl alcohol composite film

Abstract All-fiber humidity sensor based on Michelson interferometer with hyaluronic acid (HA) and polyvinyl alcohol (PVA) composite film is investigated. The interferometer is fabricated by fusing 691 μm thin-core fiber (TCF) with single mode fiber (SMF) together and melting the other end of the TCF into a circular shape. The outer of the interferometer is coated with HA and PVA composite film. As far as we know, hyaluronic acid is used in relative humidity (RH) measurement for the first time. Through wavelength and intensity demodulation, the proposed sensor’s maximum sensitivity is −0.1679 nm/%RH and −0.148 dB/%RH, respectively. Besides, the sensor’s cross-sensitivity is low (0.0727%RH/°C). Therefore, the proposed sensor with hyaluronic acid has great potential in humidity measurement.

Changes of thermal properties and microstructure of nano‐ZnO/polylactic acid composite films during Zn migration

In this study, polylactic acid (PLA) films with different nano‐ZnO concentration (0, 1, 3, 5, 7, 9, and 15%wt) were obtained by casting method. Overall migration values and specific migration values were studied in different food simulants (10% [v/v] ethanol and isooctane). The results demonstrated that overall migration of the composite films and specific migration of Zn2+ was higher in 10% (v/v) ethanol solution than in isooctane solution. The release of Zn2+ was affected by the percentage of nano‐ZnO in the composite films and food simulants. The migration of Zn in this study was mainly caused by polymer softening and degradation leading to the dissolution of Zn. Scanning electron microscope analysis indicated that with the migration of Zn2+, the structure of the composite films changed greatly. Differential scanning calorimeter analysis indicated that the thermal stability was decreased and the glass transition temperature and crystallization temperature were reduced.

Effects of microcrystalline cellulose surface modification on the mechanical and thermal properties of polylactic acid composite films

ABSTRACT Microcrystalline cellulose (MCC), extracted from distiller’s grains by nitric acid-ethanol hydrolysis, was prepared for PLA composite films by solution casting. MCC based on the optimum comparison was characterised by particle size analysis and scanning electron microscopy. The results show that the ultrasound combined sulphonation treatment was remarkable for the surface structure of MCC, compared with that modified by sulphonation and ultrasound methods. The MCC/PLA composite films were analysed using Fourier-transform infrared spectroscopy (FT-IR), mechanical properties and thermal resistance. The results show that the properties and performance of MCC/PLA composite film using ultrasound combined sulphonation treatment are obviously better than those of modified films by other methods. For the modified MCC/PLA composite film by sulphonation and ultrasound methods, the FT-IR analysis carried out a large number of hydroxyl groups that are hydrolysed, the tensile strength upped to 505.24 MPa and the thermal-decomposed temperature increased to 320°C from 260°C. The modified MCC would be a beneficial filling material for the properties of PLA composites.

Impacts of cellulose nanofibril and physical aging on the enthalpy relaxation behavior and dynamic mechanical thermal properties of Poly(lactic acid) composite films

We herein report the influences of cellulose nanofibril (CNF) and physical aging on the enthalpy relaxation behavior, thermal transition, and dynamic mechanical properties of eco-friendly poly(lactic acid) (PLA) composite films with 0.5–7.0 wt% CNF loadings, which were fabricated by using a facile masterbatch-based melt-compounding process. For the purpose, melt-quenched neat PLA and PLA/CNF composite films were aged physically at 45 °C for different times. The FT-IR spectra revealed that specific hydrogen-bonding interactions exist between the carboxyl groups of PLA matrix and the hydroxyl groups of CNF fillers, and that the interactions are strengthened by the physical aging. Accordingly, the increments of the peak temperature (Tp) and area (ΔHrelax) of the endothermic enthalpy relaxation at the glass transition temperature region with the aging time were suppressed significantly for the composite films with higher CNF contents, unlike the neat PLA film. In addition, the characteristic relaxation time of PLA/CNF composite films was highly enhanced, indicating the improved enthalpy relaxation and dimensional stability. This result is associated with the fact that the CNF fillers restrict the segmental mobility of PLA chains in the composite films during the physical aging at the glassy state, which was supported by the dynamic mechanical thermal data.

Novel multifunctional molecular recognition elements based on molecularly imprinted poly (aniline-co-itaconic acid) composite thin film for melamine electrochemical detection

The combination of copolymerization and molecularly imprinting technology provides functional materials with improved properties and can enhance the number of binding sites than the individual monomer. In this work, molecularly imprinted poly (aniline-co-itaconic acid) (MI-PANI-PIA) composite thin film was synthesized on glassy carbon electrode (GCE) by using an in-situ electropolymerization method using melamine (MA) as a template. The formation of the thin film was monitored by electrochemical methods and characterized by Fourier transform infrared (FTIR) spectrophotometry and scanning electron microscopy (SEM). Solvent extraction of the template generated the binding cavities in the polymer matrix which fit the target in size, shape and functionality. After the rebinding of MA, the proposed sensor shows a linear range between 0.25 × 10−9 M to 100 × 10−9 M, limit of quantification (LOQ) of 5.98 × 10−11 M and limit of detection (LOD) of 1.79 × 10−11 M respectively. The composite film showed high affinity towards MA through multiple non-covalent interactions, good reproducibility and stability with RSD 4.02% and 4.67% respectively. The developed sensor has an interesting potential for real sample testing applications with good recovery ranging from 95.87% to 101.5%. The new sensing composite material has good sensitivity and selectivity due to the synergistic effects of multi-functionality from the two polymers, porous thin film and imprinting effect. To this end, the MI-PANI-PIA can be regarded as a potential functional material for the chemical sensor development in future.

Development and properties of new kojic acid and chitosan composite biodegradable films for active packaging materials

Chitosan and kojic acid composite films (CHn-KAm) utilizing three chitosan with differing molecular weights and kojic acid in different ratios were investigated. Results showed that chitosan with higher molecular weights presented higher viscosity, mechanical properties and lower water vapor permeability. Furthermore, kojic acid addition further significantly decreased apparent viscosity, water content, water vapor permeability as well as increasing the antibacterial activity of the films. Increasing the kojic acid concentration resulted in increased levels of a*, b*, ΔE*, opacity values and a decreased L* value, as compared to chitosan films. The mechanical properties of CHn-KAm films increased significantly with kojic acid addition into chitosan. FTIR spectral analyses revealed a strong interaction in the film matrix consistent with composite film mechanical and physical properties. The CHn-KAm films showed significant antibacterial effectiveness. The results suggested that the use of chitosan with a higher molecular weight as CHn-KAm films is expected to be a promising material for food packaging.

Poly(sulfosalicylic acid)-functionalized gold nanoparticles for the detection of tetrabromobisphenol A at pM concentrations

Developing a sensitive, simple and fast sensing system for 3,3′,5,5′-tetrabromobisphenol A (TBBPA) is important because of its ubiquitousness and high toxicity. In this work, a gold nanoparticles (AuNPs) and poly(sulfosalicylic acid) (PSSA) composite film (AuNPs-PSSA) is fabricated in-situ on an electrode surface via cyclic voltammetry scanning. The characterization via scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy indicate that the PSSA film is homogeneously decorated with AuNPs, and a highly uniform and thin composite film is obtained. Electrochemical tests reveal that the AuNPs-PSSA film exhibits larger active surface area, lower charge transfer resistance and higher accumulation efficiency toward TBBPA than single AuNPs and PSSA film. As a result, the oxidation signals and sensing sensitivity of TBBPA are significantly enhanced on the surface of the AuNPs-PSSA. The developed TBBPA sensing platform using AuNPs-PSSA composite film, with low detection limit (25 pM) and wide linear range (0.1−10 nM), is successfully utilized to measure TBBPA level in wastewater samples. The results are highly consistent with those that obtained from high-performance liquid chromatography. The preparation and reusability of the TBBPA sensor can be automatically achieved through CV scanning, providing a promising on-line monitoring system for wastewater samples.

Preparation of starch-lipid complex by ultrasonication and its film forming capacity

Ultrasonication was used to promote the complexation between amylose and fatty acids with different states. The physicochemical properties of amylose-lipid inclusion complexes and their film-forming capacities were investigated. The fatty acids in the liquid state showed a greater complex-forming ability with amylose molecules than those in the solid state. The formation of V-amylose complex was revealed by XRD. The diffraction intensities of the corn starch-fatty acid complexes followed the order: capric acid > octanoic acid > lauric acid > myristic acid. The starch-lipid inclusion complexes with ultrasonic treatment showed higher melting enthalpies (△H) than those of untreated ones. The surface of the corn starch-fatty acid composite films became smooth after the starch underwent ultrasonic treatment. The ultrasonically-treated films exhibited lower water vapor permeability and elongation at break and higher tensile strength than those of the untreated samples.

Colorimetric multienzymatic smart sensors for hydrogen peroxide, glucose and catechol screening analysis

In this work, we present a smartphone-based multiplexed enzymatic biosensor utilizing the unique colorimetric properties of the poly(aniline-co-anthranilic acid) (ANI-co-AA) composite film coupled with horseradish peroxidase (HRP), glucose oxidase (GOx), horseradish peroxidase-glucose oxidase (GOx-HRP) and tyrosinase (Tyr) enzymes. The enzymes are immobilized on the composite polymer film by adsorption and they catalyze a reversible redox color change of the host polymer from green to blue in the presence of their substrate. A smartphone was applied as color detector, for image acquisition and data handling. A ColorLab® android application, free of charge software application, was used to enable easy and clear display of the sensors’ response indicating remarkable changes in the optical features. The results were confirmed by the spectrophotometric measurements. The developed colorimetric enzymatic biosensors were studied and optimized in relation to different experimental parameters. Moreover, the colorimetric enzymatic biosensors were applied to food and pharmaceutical analysis. It has been shown by these studies that the colorimetric biosensors are promising as quick and simple tests for handheld analysis in various fields.

Study on Aging and Recover of Poly (Lactic) Acid Composite Films with Graphene and Carbon Nanotubes Produced by Solution Blending and Extrusion

The aging, annealing, and reprocessing of the biodegradable poly (lactic) acid (PLA) based composite films incorporating graphene and carbon nanotubes were investigated in this work. Various monofiller and bifiller nanocomposite films with 6 wt.% filler content were produced by a solution-phase technique followed by extrusion. The freshly produced films were compared with the aged films after 18 months of shelf life in a room environment. The effects of aging, annealing, and melt reprocessing on the crystalline structure, the thermal stability, the hardness, and Young’s modulus were analyzed by differential scanning calorimetry (DSC), TGA, and nanoindentation methods. The fresh and the aged samples were found to have semi-crystalline materials with 3%–7% crystallinity, while the crystallinity was significantly enhanced to 34%–38% by annealing at 80 °C and subsequent slow cooling. A good dispersion was observed in the bifiller films with filler ratios of 4.5:1.5 and 1.5:4.5 [graphene nanoplatelets (GNP) to carbon nanotubes (CNT)], which affected the crystallization processes. The reprocessing at 200 °C followed by fast cooling resulted in amorphous films, which significantly reduced the hardness and Young’s modulus. The nanoindentation properties were dependent on the dispersion of nanofillers at the surfaces. The efficiency of annealing and reprocessing for the recovery and the reuse of aged nanocomposite films is discussed herein. The paper underlines that properties of the nanocomposites under investigation were influenced not only by the composition, the chemical nature of the added filler, and the processing condition, but also by the aging processes, which in turn depended on the type of nanopartcles added to PLA and the compositions. The paper provides valuable information for selection of material and processing conditions.

Synergistic Effects of Nanocomposite Films Containing Essential Oil Nanoemulsions in Combination with Ionizing Radiation for Control of Rice Weevil Sitophilus oryzae in Stored Grains.

The fumigant toxicity of eight individual essential oils (EOs; basil, cinnamon, eucalyptus, mandarin, oregano, peppermint, tea tree, and thyme) and one binary combination (thyme and oregano) for control of the rice weevil, Sitophilus oryzae, were investigated. In bioassays, all individual and combined EOs were toxic to the rice weevil. Eucalyptus EO exhibited the highest toxicity among the individual EO treatments, causing 100% mortality at a minimum concentration of 0.8 µL/mL after 24 hr of exposure. The combination treatment of oregano and thyme EO displayed higher fumigant activity than the individual oregano or thyme treatments. A stable oil-in-water nanoemulsion was evaluated using high-pressure homogenization (microfluidization [MF]) and varying the pressure and number of cycles. The droplet size of the emulsions was found to decrease from 217 to 71 nm and encapsulation efficiency increased from 37% to 84% with increasing MF pressure and number of cycles. The optimum conditions for preparing the mixture of oregano and thyme EO nanoemulsions were evaluated to be homogenization pressure of 103 MPa and three cycles. Incorporating an oregano:thyme nanoemulsion (0.75%) into cellulose nanocrystal (CNC) containing chitosan (CH/CNC), methyl cellulose (MC/CNC), and polylactic acid (PLA/CNC) composite films resulted in extended diffusion matrices causing 32% to 51% rice weevil mortality after 14 days exposure. Irradiation at 200 Gray alone caused 79% mortality and increased to 100% when combined with the bioactive chitosan film containing the oregano:thyme nanoemulsion. PRACTICAL APPLICATION: A binary combination of oregano:thyme has potential as a biopesticide against stored product pests. The encapsulation of EO nanoemulsions into biopolymeric support could be used for bioactive packaging to prevent food spoilage and extend shelf life. Combining bioactive films with irradiation can provide complete control of rice weevil in packaged rice. The system developed in this research may also be extended to explore other food-packaging films with various food models to control different types of stored pests.

Plasticized Cellulosic Films by Partial Esterification and Welding in Low-Concentration Ionic Liquid Electrolyte.

Alternatives to petroleum-based plastics are of great significance not only from the point of view of their scientific and practical impact but to reduce the environmental footprint. Inspired by the composition and structure of wood’s cell walls, we used phenolic acids to endow cellulosic fibers with new properties. The fiber dissolution and homogeneous modification were performed with a recyclable ionic liquid (IL) (tetrabutylammonium acetate ([N4444][OAc]):dimethyl sulfoxide) to attain different levels of reaction activity for three phenolic acids (p-hydroxybenzoic acid, vanillic acid, and syringic acid). The successful autocatalytic Fischer esterification reaction was thoroughly investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and nuclear magnetic resonance spectroscopy (13C CP-MAS, diffusion-edited 1H NMR and multiplicity-edited heteronuclear single quantum coherence). Control of the properties of cellulose in the dispersed state, welding, and IL plasticization were achieved during casting and recrystallization to the cellulose II crystalline allomorph. Films of cellulose carrying grafted acids were characterized with respect to properties relevant to packaging materials. Most notably, despite the low degree of esterification (DS < 0.25), the films displayed a remarkable strength (3.5 GPa), flexibility (strains up to 35%), optical transparency (>90%), and water resistance (WCA ∼ 90°). Moreover, the measured water vapor barrier was found to be similar to that of poly(lactic acid) composite films. Overall, the results contribute to the development of the next-generation green, renewable, and biodegradable films for packaging applications.

Feasibility of poly-vinyl alcohol/starch/glycerol/citric acid composite films for wound dressing applications

This work addresses the competence of PVA/starch/citric acid (PVA/St/CA) based composite films for wound dressing applications. Literature reported composition of PVA, starch and glycerol were adopted and the optimality of crosslinking temperature (40 to 60 °C) and citric acid concentration (0.5 to 3 g) have been investigated during solution casting based composite film fabrication. The prepared polymer films have been characterized with swelling index, solubility based biodegradability, gel fraction, mechanical strength, water vapor transmission rate and antimicrobial effectiveness. The optimized film (composition) were analyzed to possess excellent swelling (260.5 ± 2.9%) and in-vitro degradation (45.5 ± 1.8-59.8 ± 0.4% degradation, during 14 days) characteristics. Further, the film possesses enhanced combinations of water vapor transmission rate and antibacterial activity with Gram-negative (Escherichia coli) and Gram-positive (Listeria monocytogenes) bacteria. With all these promising characteristics, the low temperature (50 °C) and long duration (12 h) fabricated PVA-St-CA films have been inferred to be a potential candidate for wound dressing applications.

Poly(lactic acid) composite films reinforced with microcrystalline cellulose and keratin from chicken feather fiber in 1‐butyl‐3‐methylimidazolium chloride

ABSTRACTAmphiphilic keratin from chicken feather fiber (CFF) and hydrophilic cellulose were incorporated as fillers into hydrophobic poly(lactic acid) (PLA) polymer blend. This study implemented ionic liquid (IL) of 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) to dissolve the 1 wt % fillers. The composite films were compared with and without the addition of IL prepared from five sets of ratios of CFF to MCC using measuring mixers and compression molding. Thermal analysis showed that increase in CFF composition decreases the glass‐transition temperature (T g), and crystallization temperature (T c) as well as increases the degree of crystallinity. PLA composite with the 70/30 ratio of CFF to MCC was found to be the optimum composition in obtaining considerably low T g and high crystallinity. BMIMCl enhanced the miscibility of the composites as observed in scanning electron microscope images and single T g. Apart from creating porous structure and lowering mechanical hardness, BMIMCl also decreased the thermal stability of the PLA composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47642.