Fibrous Films Research Articles

Nanomechanical, Mechanical Responses and Characterization of Piezoelectric Nanoparticle-Modified Electrospun PVDF Nanofibrous Films

Limitless implementations of nanofibrous membrane show the importance of understanding the nanomechanical responses for water purification and piezoelectric nanogenerator applications. Here, the polyvinylidene fluoride (PVDF) electrospun nanofibrous films doped by 0.01, 0.05 and 0.1 wt% of ZnO nanoparticles were prepared in the method of electrospinning. Characterizations of PVDF nanocomposite fibrous films were inspected using field emission scanning electron microscope, thermogravimetric analysis, water contact angle, uniaxial tensile test and nanoindentation technique. The influence of minimal concentration of piezoelectric nanoparticles on the morphological, water contact angle, dynamic water contact angle, piezoelectric, thermal and mechanical stabilities of nanocomposite fibrous films was examined. The nanoscale mechanical properties of the PVDF/ZnO nanofibrous films were performed by nanoindentation technique at different spots of nanofibrous mat to examine the elastic–plastic behavior of membranes. The eventual ZnO nanoparticle-modified nanofibrous membranes have been shown nano-level fibers, considerable hydrophilicity and preferable thermal, mechanical and piezoelectric properties. The doping of polymer by 0.1 wt% of ZnO nanoparticles exposed significant enhancement of thermal, mechanical and nanomechanical responses of the melting temperature 2% (170– $$173\,^{\circ }\hbox {C}$$ ), tensile strength 20% (2.418 MPa), elastic modulus 18% (2.418 GPa) and hardness 60% (235 MPa) and piezoelectric coefficient 13.42 pC/N of the nanofibrous films. These understandings of nanoscale properties are highly promising in the development of sensor and actuators, biomedical, energy harvesting and water filtration devices.

Flexible/self-supported zeolitic imidazolate framework-67 film as an adsorbent for thin-film microextraction

A flexible/self-supported zeolitic imidazolate framework-67 (ZIF-67) film was fabricated and applied as an adsorbent in the thin-film microextraction technique. This sorbent was synthesized by fabricating the electrospun cobalt oxide fibers, followed by phase transformation to the ZIF-67 fibrous film. The prepared film was used for the extraction of ethion (as an organophosphorus pesticide) prior to its determination by secondary electrospray ionization-ion mobility spectrometry. To obtain high extraction efficiency, some synthesis and extraction parameters (e.g., ionic strength, pH, stirring speed, and extraction time) were assessed and optimized. The linear dynamic range was obtained between 0.5 and 100 μg L−1 with a detection limit of 0.1 μg L−1. The relative standard deviations of intra-day and inter-day were less than 10% and 11%, respectively. Ethion was successfully determined in different real samples (underground water and agricultural wastewaters) by this method and the obtained recoveries were in the range of 91–107%, for spiked samples.

Sol-gel synthesis of p-type zinc oxide using potassium permanganate

Polycrystalline, p-type ZnO were synthesized by KMnO4 doping using the sol-gel deposition process. Depending on the amount of doping, the addition of KMnO4 into ZnO resulted in either fibrous or porous film morphology. Optically, the films were transparent with transmittance ranging from 82∼88% depending on doping concentration. The p-type doping were confirmed using Hall effect measurements and the formation of rectifying pn junction with n-type ZnO.

Polyhedron carbon-scale stacking foldable fibrous film electrode with high capacitance performance from chitin fiber cloth for super flexible supercapacitors

This work is concerned with exploring high-performance flexible carbon electrode materials for supercapacitors derived from low-cost commercially-available fabrics. Herein, through direct carbonization without any additional pre-treated process and without any activators as well as any templates, we explored different carbonization temperatures to develop a super flexible carbon film derived from chitin fiber textile. The as-obtained carbon fibrous films are found to possess a novel unique microstructure and ultra-high specific surface areas (up to 382.2 m2 g−1), formed via irregular stacking and inter-connection of numerous polyhedron carbon-scales with much crevices and grooves. They present super high mechanical flexibility capable of being repeatedly folded and exhibited a very high capacitance performance with a maximum specific capacitance of up to 114.9 F g−1 at 1 A g−1 and an excellent cycling performance with about 94.0% of capacitance retention after 5000 charge-discharge cycles at 1 A g−1. The carbon fibrous film from biomass textiles shows great promise for applications as flexible electrode in energy storage.

Fluorenone-based organogel and self-assembled fibrous film: Synthesis, optical properties and reversible detection of aniline vapor

Two new low-molecular mass organic gelators (LMOGs) based on fluorenone and 3,4,5-tris(dodecyloxy)benzamide auxiliary group (SOF and DOF) were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. Both compounds exhibit 1π,π* transitions in the UV region, and broad, structureless intramolecular charge transfer (1ICT) absorption bands in the visible spectral region. Both compounds are emissive in solution at room temperature, which can be attributed to 1ICT state. In addition, the gel properties of the two compounds in 10 solvents was studied. Compared to SOF with a single auxiliary group, DOF bearing two auxiliary groups are easier to form gels in different solvents. Fluorescence behavior and sensing performance studies of DOF xerogel film obtained by self-assembling demonstrated that this film is chemically stable, and reversible and selective to the presence of aniline vapor through the photoinduced electron transfer (PET) mechanism. The self-assembled properties of the LMOGs will be more conducive to the functionalization of photofunctional materials.

Controlled engineering of highly aligned fibrous dosage form matrices for controlled release

In this study, complex drug-cellulose acetate (CA) composite films were designed and fabricated possessing pre-determined grid spacing for inter-connected fibrous films. Ibuprofen (IBU) was selected as the active ingredient and grid spacing was varied between 300 and 500 μm (fiber diameter ∼ 35 μm) for various geometries. Process parameter impact on fiber morphology and deposition was investigated. FTIR confirmed IBU encapsulation and XRD analysis indicated the drug was dispersed (amorphous) in films. Inter-connected grid void geometry was shown to impact water contact behavior, and drug release mechanism was shown to be Fickian diffusion. Furthermore, drug release rate depended on geometry of engineered structures. The findings suggest a spatial design approach for modulated drug release from bespoke drug delivery dosage forms.

Hierarchically aligned fibrous hydrogel films through microfluidic self-assembly of graphene and polysaccharides.

Despite significant interest in developing extracellular matrix (ECM)-inspired biomaterials to recreate native cell-instructive microenvironments, the major challenge in the biomaterial field is to recapitulate the complex structural and biophysical features of native ECM. These biophysical features include multiscale hierarchy, electrical conductivity, optimum wettability, and mechanical properties. These features are critical to the design of cell-instructive biomaterials for bioengineering applications such as skeletal muscle tissue engineering. In this study, we used a custom-designed film fabrication assembly, which consists of a microfluidic chamber to allow electrostatic charge-based self-assembly of oppositely charged polymer solutions forming a hydrogel fiber and eventually, a nanocomposite fibrous hydrogel film. The film recapitulates unidirectional hierarchical fibrous structure along with the conductive properties to guide initial alignment and myotube formation from cultured myoblasts. We combined high conductivity, and charge carrier mobility of graphene with biocompatibility of polysaccharides to develop graphene-polysaccharide nanocomposite fibrous hydrogel films. The incorporation of graphene in fibrous hydrogel films enhanced their wettability, electrical conductivity, tensile strength, and toughness without significantly altering their elastic properties (Young's modulus). In a proof-of-concept study, the mouse myoblast cells (C2C12) seeded on these nanocomposite fibrous hydrogel films showed improved spreading and enhanced myogenesis as evident by the formation of multinucleated myotubes, an early indicator of myogenesis. Overall, graphene-polysaccharide nanocomposite fibrous hydrogel films provide a potential biomaterial to promote skeletal muscle tissue regeneration.

A latent crosslinkable PCL-based polyurethane: Synthesis, shape memory, and enzymatic degradation

Abstract

Removal of fluoride and aluminium using plant-based coagulants wrapped with fibrous thin film

Abstract The coagulation activity of Moringa oleifera seed and Hibiscus esculentus (okra) mucilage were assessed for their ability to remove both anionic and cationic contaminants in aluminium sulphate and hydrofluoric acid synthetic wastewater. The effect of encasing these coagulants in a fibrous thin film along with their effect on pH and concentration were also assessed. Assessment using the jar test showed a 79.9% aluminium reduction and 91.7% fluoride reduction using okra mucilage and Moringa oleifera, respectively. Besides that, there was no effect on both the pH and coagulation activity in the application of fibrous thin film. The plant-based coagulation activity is comparable with conventional coagulant as fluoride removal treated by polyaluminium chloride formulation was 85.3 ± 0.8% with the optimum dosage of 3 g/L. The significance of these findings in the application of fibrous thin film with plant-based coagulants could be an advantage for industries to commercialise mechanically prepared coagulants, which has a much longer shelf life as compared to chemically prepared coagulants, as it has the potential to reduce the turbidity associated with mechanically prepared coagulants. Also, these results indicate the possibility of having a cost-effective yet environmentally friendly water treatment solution that combines the application of both plant-based and conventional coagulants.

Continuous end-to-end production of solid drug dosage forms: Coupling flow synthesis and formulation by electrospinning

Based on the concept of continuous manufacturing an end-to-end benchtop device was developed unprecedented for the production of solid drug dosage forms by connecting flow synthesis and formulation via electrospinning (ES). Together with the optimized two-step continuous-flow synthesis of acetylsalicylic acid (ASA) a water-soluble polymeric excipient (polyvinylpyrrolidone K30, PVPK30) was introduced. The resulting polymeric solution could be readily electrospun into solid nanofibers with high purity in one single step due to the excellent yet gentle drying effect of ES. The ASA-loaded fibers were electrostatically deposited onto a water-soluble pullulan sheet and the obtained double-layered films were continuously cut into orally dissolving webs (ODWs) as final dosage formulation. The synthesis as well as the dosing of the fibrous films were monitored by Process Analytical Technology (PAT) tools (IR and Raman spectroscopy) with active feedback on product quality. The successful coupling of flow synthesis and fiber formation confirms that ES enables versatile formulation of pharmaceuticals in future continuous production systems.

Flexible surface-enhanced Raman scattering-active substrates based on nanofibrous membranes

Surface-enhanced Raman scattering (SERS) has emerged as an excellent analytical tool for the effective detection and fingerprint identification of various chemicals. Recently, significant progress has been made in the fabrication of SERS-active substrates using simple, inexpensive, and affordable methods. The full potential of universal SERS diagnostics will likely be realized with the development of approaches and devices capable of effectively detecting analytes on various surfaces as well as in multicomponent media. In addition, the combination of implantable or wearable SERS-active substrates and remote portable devices enables real-time diagnostics that ideally fit the concept of personalized medicine. In this paper, we summarize recent achievements in fabricating flexible SERS substrates made of cellulose paper, polymer membranes, and textile fibrous films. Emphasis is placed on the in-situ extraction and detection of various chemicals in real-world surfaces and complex media using flexible nanofibrous SERS platforms. The potential SERS applications and future perspectives in on-site diagnostics are also discussed.

Synthesis, electrospinning and in vitro test of a new biodegradable gelatin-based poly(ester urethane urea) for soft tissue engineering

Biodegradable polyurethanes have been studied as scaffolds for tissue engineering due to their adjustable physico-chemical properties. In this work, we synthesized a biodegradable gelatin-based poly(urethane urea) using polycaprolactone-diol, as soft segment, and isophorone diisocyanate and gelatin from cold water fish skin as hard segment. The synthesis was confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance and the influence of the amount of gelatin introduced in the polymer backbone was analyzed by thermal analysis. Gelatin-based poly(urethane urea) electrospun fibrous mats and solvent cast films were then produced and their physico-chemical and biological properties studied. They present an amorphous structure, elastomeric behavior and water contact angles typical of hydrophobic surfaces. Hydrolytic degradation was analyzed in phosphate buffer saline (PBS), lipase and trypsin solutions. No mass changes were detected during 37 days in PBS and trypsin while significant degradation by lipase was observed. Human foetal foreskin fibroblasts were seeded on the fibrous mats and films. Populations were evaluated by colorimetric cell viability assays and morphology by fluorescence imaging. The substrates supported cell adhesion and proliferation. The novel gelatin-based poly(urethane urea) fibrous mats offer attractive physico-chemical and biological properties for soft tissue engineering applications.

Positive effect of wrapping poly caprolactone/polyethylene glycol fibrous films on the mechanical properties of 45S5 bioactive glass scaffolds

Abstract45S5 bioactive glass (BG) scaffolds show great potential in bone tissue engineering due to their superior osteoinductivity and osteoconductivity. However, such scaffolds generally possess poor mechanical properties. Here, inspired by the reinforcing principle of confined concrete elements in civil engineering, poly caprolactone (PCL)/polyethylene glycol (PEG) film‐wrapped 45S5 BG scaffolds were prepared by gluing highly porous foam–replicated BG scaffolds and electrospun PCL/PEG films together with a PCL layer. The results showed that the compressive strength of the PCL/PEG film‐wrapped scaffolds was greatly improved, compared to that of unwrapped BG scaffolds. Moreover, the PCL/PEG film exhibited hydrophilicity, responsible for improved cell activity with respect to the hydrophobic PCL one. Thus, the present work introduces a convenient approach to improve the mechanical properties of highly porous bioceramic scaffolds, and is relevant for future robust scaffold design.

Preparation and performance of PMMA/R-TiO2 and PMMA/A-TiO2 electrospun fibrous films

ABSTRACTIn this paper, the PMMA/R-TiO2 and PMMA/A-TiO2 nanofiber membranes were prepared by electrospinning and its photocatalytic performance was studied. Accordinly, the obtained composites nanofibers were characterized by SEM, Porosity and TG in order to characterize morphologically the nanostructures and their distribution in the polymeric matrix, thermal properties. The R-TiO2 and A-TiO2 content of 5%, the minimum average fiber diameters of 436 nm and 409 nm, the fibers appear smooth and continuous, and the two kinds of composite fibers have higher porosities. The TG curve showed that PMMA/R-TiO2 nanofibers residual amount was higher than PMMA/A-TiO2, which indicated that R-TiO2 could improve thermal stability of the composites. It evaluated their photocatalytic activity by degradation of some dyes and methyl orange in an aqueous medium. The results showed that with the increase of TiO2 content, the composite nanofibers degradation rate of methyl orange improved. At the same conditions, when the TiO2 content was 10%, the photocatalytic degradation rate of PMMA/R-TiO2 and PMMA/A-TiO2 composite nanofibers were 21.8% and 51.3% respectively.

Insights into effects and mechanism of pre-dispersant on surface morphologies of silica or alumina coated rutile TiO2 particles

Silica and alumina coated rutile TiO2 samples with various surface morphologies were fabricated using four different pre-dispersants. Using sodium silicate nonahydrate (SSNH) as pre-dispersant, the received sample displayed the best acidic stability. The addition of SSNH could induce layer-by-layer growth of hydrous silica via enhancing the dispersion of hydrous silica nucleus and accelerating the dehydration condensation rate of silica film. Alumina coated rutile TiO2 sample obtained by polyethyleneglycol 1000 (PEG) presented the highest dispersion stability. The existence of PEG can induce the formation of fibrous hydrous alumina film, which would increase the steric hindrance and the promotion of dispersion stability.

Using aligned poly(3-hexylthiophene)/poly(methyl methacrylate) blend fibers to detect volatile organic compounds

In this study, we developed a novel sensing material fabricated using a poly(3-hexylthiophene) (P3HT)/poly(methyl methacrylate) (PMMA) blend fiber on a glass substrate. The sensing materials can easily be used for sensing toluene vapor detected from extinction spectral changes. The extinction spectra variation is noted from the absorption of volatile organic compounds in a highly specific surface area of fibrous coating. An electrospinning technique is applied to generate a nonwoven structure and uniaxial orientation by fibrous coating. The response of the uniaxially orientated fibrous film is even improved at several toluene vapor concentrations. The best detection limit of this well-aligned fibrous film is up to 200 ppm for toluene vapor.

Application of Chlorophyll as Sensitizer for ZnS Photoanode in a Dye-Sensitized Solar Cell (DSSC)

Zinc sulphide thin films have been synthesized by the electrodeposition method onto stainless steel substrate followed by dipping in acetone solution of chlorophyll in different time intervals to form photosensitised thin films. The photoelectrochemical parameters of the films have been studied using the photoelectrochemical cell having the cell configuration as follows \( {\rm{photoelectrode/NaOH}}\left({1\;{\rm{M}}} \right) + {\rm{S}}\left({1\;{\rm{M}}} \right) + {\rm{N}}{{\rm{a}}_2}{\rm{S}}\left({1\;{\rm{M}}} \right){\rm{/C}}\,\,\left({{\rm{graphite}}} \right)\). The photoelectrochemical characterization of the semiconductor film and dye-sensitised films has been carried out by measuring current–voltage (I–V) in the dark, power output and photoresponse. The study proves that the conductivity of both ZnS film and dye-sensitised ZnS films are n-type. The power output curves illustrate that open circuit voltage (Voc) and short circuit current (Isc) increase from 0.210 V to 0.312 V and from 0.297 mA to 0.533 mA, respectively. The fill factor initially decreases from 0.299 to 0.213 and then increases to 0.297 irregularly whereas efficiency increases from 0.047% to 0.123%. The UV–Vis absorbance spectrum of chlorophyll in acetone shows the presence of chlorophyll. The structural morphology of the ZnS thin films has also been analysed by using x-ray diffraction technique (XRD) and a scanning electron microscope (SEM). The XRD pattern shows the formation of nanocrystalline ZnS thin films of size 65 nm and the SEM images confirm the formation of fibrous film of ZnS. The energy diffraction analysis of x-ray confirms the formation of ZnS thin films.

Carvacrol loaded electrospun fibrous films from zein and poly(lactic acid) for active food packaging

The composite fibrous films were developed from zein and poly(lactic acid) (PLA) by incorporating carvacrol at three different concentrations (5, 10 and 20%) using electrospinning. The morphology and size of fibers obtained from both zein and PLA were affected by the level of the incorporated carvacrol. The Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) results showed that carvacrol was encapsulated in electrospun zein and PLA fibers. The antioxidant activity of carvacrol loaded zein fibers ranged from 62 to 75%, while antioxidant capacity of PLA fibers varied from 53 to 65% for 5–20% carvacrol content. The composite fibrous films showed a sustained diffusion controlled release behavior. Preliminary studies on whole wheat bread samples showed that carvacrol loaded electrospun zein and PLA fibers are able to preserve bread samples, indicating that they are good candidates for active food packaging applications to extend the shelf life of whole wheat bread.

Release behavior under proteinase K and existing position of Domiphen® in its complexed poly-L-lactic acid micro-fibers electrospun from solution and W/O emulsion

To study the release behavior and the existing position of Domiphen® in its its complexed poly-L-lactic acid (PLLA) micro-fibers, two series of fibrous films were prepared by electrospinning solution and W/O emulsion, which was added to Domiphen® directly and emulsified by Domiphen®, respectively, by complexing methods. The mass ratio of Domiphen® to PLLA was 0.25%, 0.5%, 0.75%, and 1% for both methods. According to the scanning electron microscopic observation, W/O emulsion and fibers of narrow-distributed diameters were obtained by W/O emulsion electrospinning. Fluorescence microscopic observation suggested that Domiphen® was incorporated within fibers by W/O emulsion electrospinning. X-ray diffraction and differential thermal analysis characterization suggested that Domiphen® complexed well with PLLA according to noncrystalline Domiphen® existing within and on PLLA fibers prepared by both methods. Domiphen® release curves were prepared and fitted after the amount of Domiphen® released from the PLLA fibers was determined by high-performance liquid chromatography. It was discovered that, with regard to the fibrous films prepared by homogeneous solution electrospinning, Domiphen® released from fibers in accordence with the Freundlich’s equation suggesting that Domiphen® almost existed within the outermost border of the fiber cross section and its release behavior could be considered as the counter adsorption process, while with regard to the fibers prepared by W/O emulsion electrospinning, the release curves were S shape under the effect of proteinase K degradation and could be fitted to the corrosion-mechanism Peppas’ equation of n value >0.5, which suggested that Domiphen® existed both on the surfaces in small proportion and the inner border of the core-sheath fibers in big proportion.

Electrospun poly(vinyl alcohol)/permutite fibrous film loaded with cinnamaldehyde for active food packaging

ABSTRACTElectrospun ultra‐fine poly(vinyl alcohol)/permutite fibrous film loaded with cinnamaldehyde essential oil was successfully fabricated.The morphology of fibrous filmswas characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The fibrous film exhibited microstructure features with high porosity with the pore size distributed ranging from 1.7 nm to 56.7 nm. And the root‐mean‐squared roughness of fibers lifted to 546.5 nm when the addition of cinnamaldehyde essential oil (CEO) reached 0.25 mL. Attenuated total reflectance‐fourier transform infrared (ATR‐FTIR) spectroscopyconfirmed the existence of CEO in fibrous films and revealed physical interaction rather than chemical interactions existing between the film matrix and CEO. Endothermic peaks presented in differential scanning calorimetry (DSC) profile were probably rooted from existed mesoporous adsorption between the highly porous film matrix and CEO. Furthermore, the PVA/permutite/CEO fibrous film prolonged the shelf life of strawberries, confirming that the PVA/permutite/CEO fibrous film may be of interest for the development of active food packaging. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46117.