Recent Patents on Nanotechnology - Volume 13, Issue 3, 2019

Background: In recent decades, nanofiber-based materials have been considered as one of the top interesting fundamental materials for academic studies and practical applications. However, the electrospinning, as the most popular method for manufacturing nanofibers, is plagued by its low productivity. The first patent about electrospinning was emerged in 1934 and the needleless electrospinning is regarded as one of the most promising methods to realize the high throughput of nanofibers. Methods: This review compares the recent needleless spinning technologies from limited liquid surfaces to free liquid surfaces for improvement of nanofiber throughput. The aim of this review is to reveal the merits and drawbacks of recent methods in practical employment. The view focuses also on the future concern of the needleless electrospinning. Results: The current needleless electrospinning is featured with the properties: 1) high throughput; 2) lower voltage supply for the stable spinning process; 3) narrow fiber diameter distribution, followed by the drawbacks of poor long-term spinning process and limitation of a good bonding of low voltage supply. Conclusion: This review provides an update on needleless electrospinning methods for high throughput of nanofibers for industrial applications.

Background: Many spinning patents and technologies have been explored to produce diverse types of nanomaterials for different applications. As a novel method, the blown bubble-spinning is a one-step process for fabrication of nanofibrous bundles. Method: In this study, polyamide6/66(PA6/66) nanofibrous bundles filled with different concentrations of multi-walled carbon nanotubes (MWCNTs) were prepared by the blown bubble-spinning. The dispersion of MWCNT in nanofibers under different treatments was investigated and a detailed characterization focusing on the influence of the presence of MWCNT on the morphology, thermal property and electrical property was carried out. Results: The results showed that MWCNTs treated by Tween60 and ultrasonication were embedded in the PA6/66 nanofibers with uniform dispersion. In addition, it was observed that thermal stability and electrical conductivity of nanofibrous bundles increased with an increase in MWCNT content. Conclusion: The PA6/66/MWCNT nanofibrous bundles fabricated by the blown bubble spinning have the great potential applications in sensors and supercapacitors.

Backgrounds: N-halamine antibacterial materials have been extensively explored over the past few decades due to their fast inactivation of a broad spectrum of bacterial and rechargeability. Electrospun nanofibers loaded with N-halamines have gained great attention because of their enhanced antibacterial capability induced by the larger specific surface area. The patents on electrospun nanofibers (US20080679694), (CN2015207182871) helped in the method for the preparation of nanofibers. Methods: In this study, a novel N-halamine precursor, 3-(3'-Chloro-propyl)-5,5-dimethylimidazolidine- 2,4-dione(CPDMH), was synthesized. Antimicrobial electrospun Cellulose Acetate (CA) nanofibers were fabricated through impregnating CPDMH as an antimicrobial agent into CA fibers by the bubble electrospinning. The surface morphologies of CA/CPDMH nanofibrous membranes were characterized by Scanning Electron Microscope (SEM). Results: The chlorinated fibrous membranes (CA/CPDMH-Cl) exhibited effective antimicrobial activity against 100% of S. aureus and E. coli O157:H7 within 1 min and 5 min, respectively. The CA/CPDMH-Cl nanofibrous membranes showed good storage stability under the dark and excellent durability towards UVA light exposure. Meanwhile, the release of active chlorine from the chlorinated nanofibrous membranes was stable and safe. Besides, the addition of CPDMH could improve the mechanical property, and chlorination did not obviously affect the strength and elongation of the nanofibrous membranes. Conclusion: CPDMH could endow the electrospun CA nanofibers with powerful, durable and regenerable antimicrobial properties. It will provide a continuous and effective method for health-care relative industrial application.

Background and Objective: The air-flow field of the air centrifugal spinning is simulated and measured. The simulated air velocities coincide well with the measured ones, confirming the correctness of the air-flow field model. Methods: The polymer drawing in the air-flow field of the air centrifugal spinning is modeled and simulated. Effects of the rotation speed and initial air velocity on the diameter and radius vector of the threadline are investigated. Results: The air velocity is found to decrease with the increase of the distance away from the nozzle exit. Simulation results show that both larger rotation speed and higher initial air velocity can reduce the threadline diameter. Conclusion: The radius vector of the threadline increases rapidly with the increase of the initial air velocity, which is helpful to reduce the threadline diameter.

Background: Nanocomposites loaded with metal oxides, such as CuO and ZnO, have excellent optical, electrical, mechanical and chemical properties, which result in their great potential applications in optoelectronic devices, sensors, photocatalysts and other fields. Especially, electrospun metal- oxide-loaded nanofibers have attracted much attention in many fields. However, the single-needle Electrospinning (ES) inhibits the industrial application of these electrospun nanofiber composites. Bubble-Electrospinning (BE) is an effective free surface ES for mass production of nanofiber membranes loaded with metal oxide. Few relevant patents to the topic have been reviewed and introduced. Methods: The BE was used to prepare mass production of Cu(Ac)2 /Zn(Ac)2/ PVDF/ PAN Composite Nanofiber Membranes (CNFMs). Then PVDF/PAN CNFMs containing CuO and ZnO nanocrystals were obtained by heat-treatment. Finally, CuO nanosheets and ZnO nanorods were successfully grown on the surface of PVDF/PAN CNFMs using hydrothermal method. In addition, the morphology and crystal structure of CNFMs were investigated by scanning electron microscopy (SEM) and X-Ray Powder Diffractometer (XRD). Results: The morphology and crystal structure of the samples were characterized by SEM and XRD. The results showed the heat treatment temperature of 150oC and the hydrothermal temperature of 150oC were the optimal process parameters for the fabrication of PVDF/PAN CNFMs loaded with CuO and ZnO nanocrystals, and a higher heat treatment temperature results in higher crystallinity of ZnO and CuO. Conclusion: CuO/ZnO/PVDF/PAN CNFMs were successfully prepared by a combination of BE, heattreatment and hydrothermal method. The ZnO/CuO beads obtained by heat treatment is the key point of growing ZnO/CuO nanocrystals, and the growth temperature has great effect on the morphology of ZnO/CuO nanocrystals.

Background: Natural latex has been widely used in medical gloves, gas masks and nipples characterized by high elasticity, good film-forming performance and flexible film, but it is seldom used in nanomaterials. Electrospinning is an effective technology for manufacturing microfibrous or nanofibrous membranes. Latex-based nanofibers can be fabricated by electrospinning. Few relevant patents to the topic have been reviewed and cited. Methods: The natural rubber latex and PVA solution were prepared for electrospinning in this study. Results: When the rubber tends to nano scales, the flexibility of natural rubber gets enhanced. Additionally, the latex fluid can be used as an additive to improve mechanical property of nanofibers. Conclusion: The electrospinning rubber nanofibers shed a new light on rubber industry.

Background: Aqueous-alumina nanofluid was prepared using magnetic stirrer and ultrasonication process. Then, the prepared nanofluid was subjected to flow through the unshielded receiver of the parabolic trough solar collector to investigate the performance of the nanofluid and the effects of the dimensionless parameter were determined. Methods: The experimental work has been divided into two sections. First, the nanofluid was prepared and tested for its morphology, dimensions, and sedimentation using X-Ray Diffraction and Raman shift method. Then, the nanofluids of various concentrations from 0 to 4.0% are used as heat transfer fluid in unshielded type collector. Finally, the effect of the dimensionless parameter on the performance was determined. Results: For the whole test period, depending upon the bulk mean temperature, the dimensionless parameters such as Re and Nu varied from 1098 to 4552 & 19.30 to 46.40 for air and 2150 to 7551 & 11.11 to 48.54 for nanofluid. The enhancement of thermal efficiency found for 0% and 4.0% nanoparticle concentrations was 32.84% for the mass flow rate of 0.02 kg/s and 13.26% for the mass flow rate of 0.06 kg/s. Conclusion: Re and Nu of air depend on air velocity and ambient temperature. Re increased with the mass flow rate and decreased with concentration. Heat loss occurred by convection mode of heat transfer. Heat transfer coefficient and global efficiency increased with increased mass flow rate and volume fraction. The thermal efficiency of both 0% and 4.0% concentrations became equal for increased mass flow rate. It has been proven that at high mass flow rates, the time available to absorb the heat energy from the receiver is insufficient.

Background & Objective: Starch-based edible films, which are transparent, odourless, biodegradable, tasteless, and semi-permeable to gases and food additives, have attracted the attention of the research community as the alternative food packaging materials to synthetic plastics. However, they pose poor water resistance and mechanical strength that should be improved for food packaging application. Few relevant patents to the topic have been reviewed and cited. Methods: Inclusion of nanoadditives in starch films can not only improve their mechanical and barrier properties but also can act as antimicrobial agent, oxygen scavenger, and biosensor. The present investigation is focussed on the effects of nanocellulose extracted from banana pseudostems on the film properties of rice starch-based edible films. Nanocellulose was extracted from dried banana pseudostems through isolation of cellulose and acid hydrolysis. Rice starch-based edible films were prepared through solution casting by adding nanocellulose of varying concentrations (0%, 2%, 4%, 6%, 8% & 10%). Results: The film properties, such as Water Vapour Permeability (WVP), mechanical strength (tensile strength, Young's modulus and percentage of elongation), film solubility in water and film colour, were determined. The test results were discussed and the effects of nanocellulose additives were studied. Conclusion: From the results, it was clear that the addition of nanocellulose had improved the film properties, making the rice starch-based edible films a promising choice for food packaging applications.