11 papers authored or co-authored cover topics such as nanofibrous aerogels, bioactive coatings, magnesium alloy stents, and thermal insulation materials.
(2023) Ceramics International, 49 (23), pp. 38058-38069. DOI: 10.1016/j.ceramint.2023.09.136
ABSTRACT: Nanofibrous aerogel composites have emerged as most promising materials for their high-temperature insulation in complex environments due to their ultra lightweight, high elasticity, and superior thermal performance. However, the release of particles caused by weak bond strength between nanofibers and aerogel, lead to insulation failure which presents serious challenge. This research presents, a novel approach to mitigate the particle release and significantly improve the overall performance of nanofibrous aerogel composites. The proposed method involves the preparation of particle-free nanofibrous aerogel composites through unique combination of sol-aerogel blending, electrospinning, and freeze-casting processes. The effect of particle release has been successfully eliminated by embedding TiO2 aerogel within SiO2 nanofibers even under rigorous conditions (weight loss rate less than 0.57%). Furthermore, the resulting nanofibrous aerogel composite exhibits exceptional thermal insulation properties, with a low thermal conductivity of 0.0251 W/mK at room temperature. Additionally, the proposed composite material configuration demonstrates superior infrared radiation suppression performance resulting in an infrared transmittance of 39.52%. The lamellar structure of the nanofibers aerogel is tailored to provide high compressive strength (2.2 kPa at 40% strain), exceptional cyclic fatigue resistance after 50 cycles, and temperature (−196 to 500 °C) conditions. The outstanding combination of thermal and mechanical properties exhibited by these nanofibrous aerogel composites makes them highly promising for stable thermal protection in extreme environmental conditions. These novel materials promise great potential for application in various engineering industries where reliable thermal insulation is critical. © 2023
(2023) Journal of Alloys and Compounds, 957, art. no. 170331, . DOI: 10.1016/j.jallcom.2023.170331
ABSTRACT: Fibrous aerogel composites have attracted considerable attention in the field of insulation materials due to their low thermal conductivity and elasticity. However, they cannot meet the thermal insulation performance under practical application conditions due to their high infrared radiation transmittance and limited thermal stability. A novel strategy for embedding anatase TiO2 nanoparticles in SiO2 nanofibers was reported herein. TiO2 nanoparticles embedded in SiO2 nanofibers with bead-on-string structures were prepared through electrospinning, which leads to enhanced binding force between nanofibers and opacifier nanoparticles and uniform dispersion of opacifier in nanofibrous aerogel composites. Combined with freeze-drying technology, nanofibrous aerogel composites with the lamellar structure were prepared, which possessed ultra-low density of 5.8 mg/cm3 and superior compression strength (6.71 kPa at 40% strain) and fast recovery after compression. In addition, the obtained aerogel composites exhibited low infrared transmittance (60% at 3 µm), thermal conductivity (0.0257 W/mk at room temperature), splendid flame-retardant properties, and thermal insulation properties. The combined structural stability and low infrared transmittance offer an ideal candidate for thermal insulation under extreme conditions. © 2023 Elsevier B.V.
(2023) Ceramics International, . DOI: 10.1016/j.ceramint.2023.09.283
ABSTRACT: Silica aerogel composites reinforced by fibers (SRF) have been used as thermal insulation walls to suppress lithium-ion batteries (LIBs) thermal runaway in electric vehicles. Increasing energy density of lithium-ion batteries brings out the requirement of higher temperature resistance and better thermal insulation performance of silica aerogel composites. Herein, we report a simple strategy for preparing aerogel reinforced by ZrO2/SiO2 fibers papers (AZSP) with double network structure for thermal insulation at high-temperature by conventional papermaking process and sol-gel method. The papermaking process made long fibers oriented perpendicular to thickness and opacifier ZrO2 fibers dispersed evenly in composites and mesoporous silica aerogels were filled in nanofibers skeleton. AZSP exhibited an excellent thermal insulation property at high-temperature with thermal conductivity of 0.039 W/(m·K) at 500 °C. The nanofibers reinforcement had been found to impart several desirable attributes to the material, including high flexibility, smooth surface suitable for stamping, painting, writing, or printing, and tensile stress of 0.74 MPa, thus rendering it an attractive option for diverse applications. Furthermore, the exceptional thermal stability of AZSP was demonstrated by the absence of any significant shrinkage deformation upon exposure to a butane flame. These remarkable properties, in conjunction with its high flexibility and thermal insulation performance, made AZSP a promising candidate for utilization as an insulation material for electric vehicle thermal management systems to mitigate the risk of thermal runaway. © 2023 Elsevier Ltd and Techna Group S.r.l.
(2022) Materials Research Express, 9 (12), art. no. 125402, .ABSTRACT: Background: Catheters are polymeric materials frequently used in clinics and are associated with the risk of inflammation and coagulation. The development of bioactive catheter surfaces is worth applying because antibiotic resistance in bacterial infections is common. Copper (Cu) ion coordinated chitosan (Chitosan-Cu) coatings on medical catheters, and several studies have recently approved its application. Objective: It is crucial to investigate the possible cytotoxicity of Chitosan-Cu coatings on surrounding cells. Methods: The effect of the Chitosan-Cu complex coating, proven to have bioactive activities at different rates on L929 cells, was examined by the CCK-8 test kit. In 24 h, the cell viabilities of samples, with Chitosan: Cu ratios of 10:0, 10:1, 50:1, and 100:1, were measured as 105.14%, 89.90%, 91.91%, and 100.75%, respectively. In 72 h, they were measured at 119.45%, 109.33%, 110.24%, and 114.45%. The surface morphology of the coating was characterized by electron microscopy, and the entity of the Cu ions in the coating was characterized by x-ray photoelectron spectroscopy. Conclusion: Cytotoxicity assays showed that Cu, with a maximum concentration of 10% by volume, showed no toxic behavior. © 2022 The Author(s). Published by IOP Publishing Ltd.
(2022) Nanomaterials, 12 (22), art. no. 3928, . DOI: 10.3390/nano12223928
ABSTRACT: The thermal radiation phenomenon is more crucial than other thermal transportation phenomena at elevated temperatures (>300 °C). Therefore, infrared radiation resistance and its performance on thermal conduction of nanofibrous aerogel with Titanium oxide (TiO2) filler have been investigated compared to control groups (silica nanofibrous aerogels with and without filler). Nanofibrous aerogel has been produced by electrospun silica nanofibers. Later, TiO2 opacifier and a non-opacifier filled materials were prepared by a solution homogenization method and then freeze-dried to obtain particle-filled nanofibrous aerogel. Moreover, the thermal radiation conductivity of the composite was calculated by numerical simulation, and the effect of the anti-infrared radiation of the TiO2 opacifier was obtained. The fascinating inhibited infrared radiation transmission performance (infrared transmittance ~67% at 3 μm) and excellent thermal insulation effect (thermal conductivity of 0.019 Wm−1K−1 at room temperature) and maximum compressive strengths (3.22 kPa) of silica nanofibrous aerogel with TiO2 opacifier were verified. Excellent thermal insulation, compression and thermal stability properties show its potential for practical application in industrial production. The successful synthesis of this material may shed light on the development of other insulative ceramic aerogels. © 2022 by the authors.
(2022) Journal of Materials Science: Materials in Medicine, 33 (10), art. no. 65, . DOI: 10.1007/s10856-022-06688-x
ABSTRACT: Chitosan coatings have shown good bioactive properties such as antibacterial and antiplatelet properties, especially on blood-contacted biomedical materials. However, as blood-contacted biomedical device, the intravascular metal stent has a burden with adverse effects on the structural integrity, such as mechanical load during implantation and substrate degradation if a biodegradable metal is used as the substrate. It is unquestionably true that the structural integrity of the coated stent is essential. The adhesion strength between the coating and the substrate positively affects it. Silane and polydopamine (PDA) interstitial layers have been investigated to improve the corrosion resistance, biosafety and adhesion strength. This work addressed this challenge by using PDA as an intermediate and glutaraldehyde as a linking agent to establish a strong link between the polymer coating and the intermediate coating. Compared with PDA-only and glutaraldehyde-linked silane layer, the novel coating displayed a notable increase in adhesion. When compared with the bare Ni-free stainless steel, the performance of the novel coating was not significantly different. This novel chitosan film on the glutaraldehyde linked-PDA interface can be applied to various metallic substrates where synergic bioactive and anticorrosive effects of PDA interstitial coating and chitosan are needed. [Figure not available: see fulltext.] © 2022, The Author(s).
(2022) Journal of Biomedical Materials Research - Part B Applied Biomaterials, 110 (8), pp. 1899-1910. ABSTRACT: Copper ions (Cu) grafted chitosan coating was prepared using the pneumatic spraying method on the silicone rubber surface. Coating’s surface properties, morphology, composition, Cu releasing behavior, antibacterial, and anti-inflammatory activities are investigated and discussed. Surface properties, composition, and morphology were investigated by scanning electron microscopy (SEM) and contact angle measurements. The antibacterial activity has been tested with Escherichia coli and Staphylococcus aureus suspensions in vitro. Besides, the morphology of the biofilm was inspected with a field emission SEM. To evaluate the anti-inflammatory activity and biosafety of the coating in vivo, the optimized coating samples and control groups were implanted subcutaneously into the back of mice. The bacterial environment model was established by injection of the bacterial suspension. The morphology and bacterial adhered on the surface of catheters and the surrounding tissues were analyzed after 5 days of implantation. As in vitro results, the number of adhered bacterial on the surface of the silicon rubber surface was decreased, and the anti-inflammatory rate was increased by the intensify of the Cu content in chitosan coating. As for in vivo results, after 5 days of implantation, there was no evident inflammation in the surrounding tissues of all catheters in all without the S. aureus injected group. In the injected chitosan/Cu coated group; the inflammation, the number of the adhered bacteria were observed less than other injected samples without Cu; no inflammation were noticeable. Results indicate that the Cu-modified chitosan coating can confer excellent antibacterial and anti-inflammatory activity as applied on medical catheters. © 2022 Wiley Periodicals LLC.
(2022) Journal of Biomedical Materials Research - Part B Applied Biomaterials, 110 (1), pp. 239-248. ABSTRACT: Biosafety of AZ31B magnesium (Mg) alloy and the effect of its degradation products on tissues, organs, and whole systems are highly needed to be evaluated before clinical application. This study serves a wide variety of safety evaluations of biodegradable AZ31B alloy on nerve cells. As a result of this in vitro study, the maximum aluminum (Al) ion and Mg ion concentrations in the medium were estimated to be 22 μmol/L and 2.75 mmol/L, respectively, during degradation. In addition, the corresponding cell mortality was observed to be 36% and lower than 5% according to the resistance curves of the cell to Mg and Al ions. Furthermore, the maximum Al ion and Mg ion concentrations in serum and cerebrospinal fluid were detected to be 26.1 μmol/L and 1.2 mmol/L, respectively, for 5 months implantation. Combining the result of in vivo dialysis with the result of ion tolerance assay experiments, the actual death rate of nerve cells is estimated between 4 and 10% in vivo, which is lower than the result of in vitro cytotoxicity evaluation. Moreover, no psychomotor disability during clinical studies is observed. Consequently, stent made of AZ31B alloy with surface treatment is feasible for carotid artery stenosis, and it is safe in terms of cell viability on the nervous system. © 2021 Wiley Periodicals LLC.
(2020) Journal of Biomedical Materials Research - Part B Applied Biomaterials, 108 (7), pp. 2868-2877. ABSTRACT: Vascular implant interventional medical catheter will contact with blood firstly after implantation. The anticoagulation and antibacterial functions of this device will determine the success or failure. Copper (Cu) has been verified to possess multi-biofunctions, but it was challenging to add the Cu metal to most materials. Take advantage of its functionality; Cu has been grafted on the material surface to improve the anticoagulation function and accelerate endothelialization. In this study, a Cu-bearing chitosan coating was prepared on the catheter to endow the anticoagulation and anti-infection functions. Besides, properties characterization and functional evaluation of the coated medical catheter were investigated. Dynamic blood clotting and platelet adhesion tests were carried out to evaluate the anticoagulation property. Besides this, the antibacterial test was used to estimate the anti-infection function. The surface energy and Cu ions release from the coating were detected and calculated by contact angles and immersion tests, respectively. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that Cu ions were grafted in the chitosan coating. Thermogravimetric analysis (TA) result showed the concentration of Cu ions in the coating. The results of dynamic blood clotting, platelet adhesion, and antibacterial tests revealed that Cu grafted in chitosan would improve the blood compatibility and anti-infection property. The surface properties and Cu ions release behavior of Cu-bearing coating revealed the reasons for multi-biofunctions. This study indicated that the Cu-bearing chitosan coating could endow the vascular implant interventional device anticoagulation and anti-infection functions, which has excellent potential for clinical application. © 2020 Wiley Periodicals, Inc.
(2019) Journal of Materials Science and Technology, 35 (1), pp. 19-22. DOI: 10.1016/j.jmst.2018.09.021
ABSTRACT: Polymer coating was widely used as a protective coating on Mg alloy stent due to its excellent deformability. However, the polymer coating with lots of macro- and micro-holes after solvent evaporation during forming process would make corrosion medium permeate easier and decrease the corrosion resistance of Mg alloy stent. In this study, a novel critical re-melting method was adopted to improve the polymer coating densification, which was evaluated by the surface morphology of coating. The corrosion resistance of Mg alloy stent after critical re-melting treatment was examined by the electrochemical and immersion tests. The results indicated that the corrosion resistance of Mg alloy stent with polymer coating was improved significantly by polymer critical re-melting treatment. © 2018
(2016) Journal of Thermal Engineering, 2 (6), pp. 978-982. ABSTRACT: insulation performance with lower thicknesses, create a market need to develop new insulation materials. Especially, vacuum insulated panels as superinsulation materials, still have an opportunity to invent new core materials from locally occurring materials like natural fibers and different kind silicates with high porosity like zeolite, sepiolite, diatomite etc. That kind of materials can be used to produce powder-glass fiber hybrid core materials. They have the positive effect on the critical inner pressure of core material. Sepiolite is a Magnesium Hydroxyl Silicate clay with high surface area and fiber-like structure. So that makes the sepiolite is an interesting material for superinsulation research works. Investigation of glass fiber vacuum insulation panels is well justified. As seen from the work, the low sepiolite content and without sepiolite addition glass fiber core materials show better thermal insulation performance. The performance differences on thermal insulation. overall the objectives have been achieved in this study.