Mehdi Sadrjahani

Bio: Mehdi Sadrjahani is an academic researcher from Amirkabir University of Technology. The author has contributed to research in topics: Electrospinning & Nanofiber. The author has an hindex of 4, co-authored 8 publications receiving 49 citations.

Aligned electrospun sulfonated polyetheretherketone nanofiber based proton exchange membranes for fuel cell applications

Abstract: In this study, electrospinning of sulfonated poly (ether ether ketone) (SPEEK) at different degrees of sulfonation (DS) was investigated. The polymer solution concentration of 22 wt% was obtained to collect smooth fiber in nanoscale range of 112 to 131 nm at various conditions. SEM observations of SPEEK nanofibers showed the decrease of diameter with increasing DS from 74% to 81%, mainly due to the increase of electrical conductivity of polymer solution at higher DS. The increase of collecting speed from 20 to 305 m/min decreased the diameter of nanofibers slightly and improved their alignment. The presence of SO3H groups in collected nanofibers was demonstrated with FT-IR analysis. WAXD patterns of SPEEK nanofibers indicated featureless amorphous peak with no crystalline regions that was broaden at higher DS and aligned nanofibers. The electrochemical impedance spectroscopy of SPEEK nanofibers showed the through-plane proton conductivity of fully hydrated nanofibrous membranes measured at room temperature were improved with DS. The proton conductivity of randomly oriented and aligned nanofibers were measured from 0.0098 S/cm to 0.0722 S/cm and from 0.0592 S/cm to 0.0907 S/cm, respectively. Aligned nanofibers exhibited more proton conductivity than randomly collected nanofibers. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Recently developed electrospinning methods: a review

Abstract: Conventional electrospinning is an effective and versatile method employed for fabricating nanofibers. However, the relatively low production rate is the major challenge of electrospinning as an economic and scalable method. Recently, several approaches have been developed to ensure the high production rate of nanofibers. This paper has reviewed the latest developed electrospinning methods, such as multi-jet, needleless, bubble, centrifuge and electro-centrifuge systems. Furthermore, the jet formation in centrifugal spinning, as well as electro-centrifuge systems, was investigated through experimental and numerical analysis.

Fabrication of Electrospun Ibuprofen-Loaded Poly(vinyl alcohol)/hyper-branched Poly(ethylenimine) Fibers and Their Release Behaviors

Abstract: A novel transdermal drug delivery system for the release of ibuprofen (IBU) was fabricated via poly(vinyl alcohol)/hyper-branched poly(ethylene imine) (PVA/PEI) nanofibrous membranes. Hence...

Tunable wicking behavior via titanium oxide embedded in polyacrylonitrile nanofiber strings of yarn

Abstract: The effect(s) of TiO2 nanoparticles on the vertical wicking behavior observed in electrospun polyacrylonitrile (PAN) nanofiber strings of yarn was investigated in this study. The capillary flow was measured in composite nanofiber strings of yarn by means of the image analysis of the rise of colored liquid soaked up in the strings of yarn; the height of liquid rise was determined as a function of time. The kinetics of capillary rise follows the Lucas–Washburn’s equation. The results obtained from the experimental design showed that the rate coefficient of the capillary rise was influenced by TiO2 nanoparticles more than the twist level in nanofiber strings of yarn. For various hot-stretching ratios, the rate of capillary rise decreased with increasing the number of TiO2 nanoparticles and the level of yarn twist. This decreasing trend was more pronounced at higher levels of yarn twist. To find how capillary behavior changed with the release of nanoparticles, the wicking mechanisms were measured at different concentrations of TiO2 nanoparticles in capillary liquid. When TiO2 nanoparticles were used in capillary liquid, they immediately filled the spaces between nanofibers in yarn and the liquid could not rise any more. The present study indicated that the wicking behavior of composite nanofiber strings of yarn was tunable provided that appropriate constructive factors, that is to say, the number of TiO2 nanoparticles and the level of nanofiber yarn twist, were chosen.

Recent Developments in Polydiacetylene-Based Sensors

Abstract: Conjugated polymers are intriguing materials that have potential practical applications in diverse interdisciplinary subjects. Among them, polydiacetylenes (PDAs) have been extensively studied due to their interesting structural, spectral, and optical features. In particular, the unique colorimetric and fluorescent transition of PDAs in response to different external stimuli makes them a novel class of sensing materials, and numerous applications of PDAs as bio- or chemosensors have been explored in the past few decades. In this review, we summarize the latest developments with regard to the applications of PDAs as a class of sensing materials presented in the literature since 2014. This review is sorted into categories based on the structural differences of diacetylene monomers, from which PDAs are generated. In addition, different forms of PDAs and various methods for improving the sensing performance of PDAs are also emphasized.

Nanofiber-Based Proton Exchange Membranes: Development of Aligned Electrospun Nanofibers for Polymer Electrolyte Fuel Cell Applications

Abstract: To ensure sustainable energy and environments for the future, nanotechnology is continuing to contribute new solutions and prospects. Materials with nanofibrous structures are attractive when it co...