Search for: polydimethylsiloxane
0.006 seconds

    Network structure and mechanical properties of polydimethylsiloxane filled with nanodiamond – Effect of degree of silanization of nanodiamond

    , Article Composites Science and Technology ; Volume 142 , 2017 , Pages 227-234 ; 02663538 (ISSN) Hajiali, F ; Shojaei, A ; Sharif University of Technology
    Reinforcement of polydimethylsiloxane (PDMS) was investigated using untreated nanodiamond (uND) and silane functionalized ND (sND) at various degrees of silanization. Scanning electron microscopy revealed an improved dispersion of ND in PDMS by silanization. The incorporation of uND and sNDs enhanced tensile strength up to 45% and 70%, respectively; however, greater improvement was observed for sNDs at very low concentrations, e.g. 0.2 wt%. The much improvement in crosslinking density, analyzed by Flory-Rehner model and Mooney-Rivlin plot, and interfacial interaction, characterized by Kraus and Cunneen-Russell plots, was also observed for sNDs. Interestingly, it was found that the extent of... 

    Characterization of Morphology and Properties of Polydimethylsiloxane/Nanodiamond Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Hajiali, Faezeh (Author) ; Shojaei, Akbar (Supervisor)
    Polydimethylsiloxane (PDMS) is one of the most important organosilicon elastomers. This polymer has a wide application such as medical engineering due to the unique characteristics, variety and ease of manufacture. Nowadays, the use of nanoparticles such as carbon nanotubes for improving the properties of elastomers is highly regarded owing to the fact that the improvement of properties such as mechanical properties broadens the applications of PDMS. Diamond nanoparticles has been the focus of numerous researchers in the past decade. In fact, nanodiamond has a good mechanical abrasion and thermal properties. In addition, the investigations proved that the nanoparticle is valuable in terms of... 

    Desulfurization of Middle Distillate Fractions by Membrane Technology

    , M.Sc. Thesis Sharif University of Technology Heydari, Hamid (Author) ; Soltaneih, Mohammad (Supervisor) ; Musavi, Abbas (Supervisor)
    In this study, the pervaporation method was used for desulfurization of gasoline. Thiophene was used as a sulfur agent and n-heptane as a representative of hydrocarbon compounds in gasoline. The composite membranes of the active PDMS layer containing the UiO-66 metal-organic framework nanoparticles are based on porous membrane PVDF. The effect of adding PVP polymer on the porosity of the PVDF membrane has been investigated. Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD) have been used to characterize nanoparticles and synthesized membranes. The effect of adding nanoparticles on the membrane performance and its sowelling effect in... 

    A plasmonic gold nanofilm-based microfluidic chip for rapid and inexpensive droplet-based photonic PCR

    , Article Scientific Reports ; Volume 11, Issue 1 , December , 2021 ; 20452322 (ISSN) Jalili, A ; Bagheri, M ; Shamloo, A ; Kazemipour Ashkezari, A. H ; Sharif University of Technology
    Nature Research  2021
    Polymerase chain reaction (PCR) is a powerful tool for nucleic acid amplification and quantification. However, long thermocycling time is a major limitation of the commercial PCR devices in the point-of-care (POC). Herein, we have developed a rapid droplet-based photonic PCR (dpPCR) system, including a gold (Au) nanofilm-based microfluidic chip and a plasmonic photothermal cycler. The chip is fabricated by adding mineral oil to uncured polydimethylsiloxane (PDMS) to suppress droplet evaporation in PDMS microfluidic chips during PCR thermocycling. A PDMS to gold bonding technique using a double-sided adhesive tape is applied to enhance the bonding strength between the oil-added PDMS and the... 

    A high-performance polydimethylsiloxane electrospun membrane for cell culture in lab-on-a-chip

    , Article Biomicrofluidics ; Volume 12, Issue 2 , April , 2018 ; 19321058 (ISSN) Moghadas, H ; Saidi, M. S ; Kashaninejad, N ; Nguyen, N. T ; Sharif University of Technology
    American Institute of Physics Inc  2018
    Thin porous membranes are important components in a microfluidic device, serving as separators, filters, and scaffolds for cell culture. However, the fabrication and the integration of these membranes possess many challenges, which restrict their widespread applications. This paper reports a facile technique to fabricate robust membrane-embedded microfluidic devices. We integrated an electrospun membrane into a polydimethylsiloxane (PDMS) device using the simple plasma-activated bonding technique. To increase the flexibility of the membrane and to address the leakage problem, the electrospun membrane was fabricated with the highest weight ratio of PDMS to polymethylmethacrylate (i.e., 6:1... 

    The effects of thymus plant extracts on single breast cancer cell morphology in the microfluidic channel

    , Article 2018 IEEE EMBS Conference on Biomedical Engineering and Sciences, IECBES 2018, 3 December 2018 through 6 December 2018 ; 2019 , Pages 647-651 ; 9781538624715 (ISBN) Ahmad, M. R ; Mansor, M. A ; Alsadat Rad, M ; Soo-Beng Khoo, A ; Ahmad, M ; Marzuki, M ; Physiological Measurement; Sarawak Convention Bureau ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Microfluidics based systems could be useful for drug discovery as they allow for miniaturization and could potentially be run as multiple parallel cell based assays. Such miniaturization allows assays at single cell level and reduces the amount of test material needed, which, in the case of natural product extracts, simplifies the preparation. Thyme species extracts have been reported to show some promising anti-cancer effects. In the present work, we used a microfluidics based system to study the effects of Thymus kotschyanusm Boiss plant extract on two human breast cancer cells lines which are MDA-MB-231 and MCF-7. For better understanding a single cancer cell death mechanism and a flow... 

    Synthesis and Properties of Functional Super Hydrophobic TiO2

    , M.Sc. Thesis Sharif University of Technology Razavi, Atieh (Author) ; Dolati, Abolghasem (Supervisor)
    Titanium nano-oxide (TiO2) coatings have been used for self-cleaning, antimicrobial, and dust-proof designs. The degree of wetting of a solid surface with water in humid air depends on how the surface tension of the existing phases relates. The ratio between these tensions estimates the contact angle between a drop of water and the surface on which it is placed. A contact angle above 150 º is essential for surface overflow. In this study, 18 different combinations of titanium oxide and FAS, PDMS and PMS nanoparticles were obtained with a static contact angle of 165 to 150 º and a dynamic contact angle of 7 º.1 to 4.5 º. Following the measurement of water droplet slip speed on a sloping... 

    Design of a Microfluidic Digital Droplet PCR

    , M.Sc. Thesis Sharif University of Technology Abedini, Ali (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    Polymerase chain reaction, abbreviated as PCR, is a method of amplifying the number of copies of a desired DNA sequence through special protocols. The rapid advance of microfluidic devices and the emerging concept of digital microfluidics has resulted into the development of digital droplet PCR (ddPCR) systems with their significant uses in the detection of rare mutations, cancer diagnosis, and surveillance. A large number of micron-sized droplets are required to perform ddPCR. in this study, To investigate the gradient of confinements induced droplet self-breakup mechanism, we carried out the computational fluid dynamics (CFD) simulations for the two-phase flow using a commercial software... 

    High-Throughput Determination of Pesticide Residues by Solid-Phase Microextraction and Micro-Solid Phase Extraction on 96-Well Plate

    , Ph.D. Dissertation Sharif University of Technology Eshaghi, Ali (Author) ; Bagheri, Habib (Supervisor) ; Es-haghi, Ali ($item.subfieldsMap.e)
    Novel high-throughput device and their applications as the microextraction systems for pesticide multiresidue determination is the centre of this research. 96 extracting unit based on solid phase microextraction and micro-Solid phase extraction were constructed and applied for high-throughput extraction.
    In the first work, a high-throughput SPME on 96-well plate together with gas chromatography-mass spectrometry was developed for the determination of pesticide residues in cucumber samples. A home-made Teflon block consisting ninety-six holes was constructed to 96 SPME fibers being positioned in. SPME fibers consisted of stainless steel rods with a 1.0 cm polydimethylsiloxane tubing... 

    Produce of Nano composite Antibacterial Coating of PDMS+TiO2+ Ag3PO4 on 316SS Using Sol-Gel Methods and its Properties

    , M.Sc. Thesis Sharif University of Technology Ghamari, Niloufar (Author) ; Afshar, Abdullah (Supervisor)
    The aim of this research is to create coatings with antibacterial and superhydrophobic properties. To evaluate this, the sourness angle test, bacterial culture and halo diameter test have been used. The results show that 316L stainless steel containing PDMS+TiO2+7%Ag3PO4 coating, which is applied by immersion method on the substrate, has a water contact angle of 152 degrees, the number of bacteria cfu.cm2 is 44000 and the halo diameter is 24 mm. which has the best performance among other examples. In order to increase the adhesion of coatings on 316L stainless steel, first heat treatment was performed and then the samples were placed in H2SO4:H2O2 solution for 1 hour to form its OH- groups... 

    Silane functionalization of nanodiamond for polymer nanocomposites-effect of degree of silanization

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 506 , 2016 , Pages 254-263 ; 09277757 (ISSN) Hajiali, F ; Shojaei, A ; Sharif University of Technology
    Elsevier B.V  2016
    The silanization of nanodiamond (ND) was successfully carried out by using the esterification reaction of hydrolyzed vinyltrimethoxysilane (VTS) in alcoholic solution. The surface carboxylic group of ND was first enhanced by thermal oxidation to increase the degree of esterification reaction. The extent of silane functionalization of ND was controlled by varying the weight ratio of VTS and oxidized ND (oxND), from 2:1 to 10:1 (w/w) in the functionalization reaction medium. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) revealed that the highest degree of silanization occurred at VTS/oxND of 5:1 (w/w), while more silane concentrations resulted in... 

    Mass transfer through PDMS/zeolite 4A MMMs for hydrogen separation: Molecular dynamics and grand canonical Monte Carlo simulations

    , Article International Communications in Heat and Mass Transfer ; Volume 108 , 2019 ; 07351933 (ISSN) Riasat Harami, H ; Amirkhani, F ; Khadem, S. A ; Rezakazemi, M ; Asghari, M ; Shirazian, S ; Sharif University of Technology
    Elsevier Ltd  2019
    In industry, utilizing membrane separation technology to purify natural gas streams is of remarkable significance. Molecular Simulation was used in the current article to study the structural and gas separation properties of polydimethylsiloxane (PDMS)/zeolite 4A Mixed Matrix Membranes (MMMs). To explore the optimal performance of MMMs, several structural analyses, namely Fractional Free Volume (FFV), Radial Distribution Function (RDF), X-Ray Diffraction (XRD) and also Glass Transition Temperature (Tg) as one of the most important properties of membranes have been evaluated. Also, the solubilities and diffusivities of periodic cells were respectively measured using MSD and adsorption... 

    Fabrication and characterization of low-cost, bead-free, durable and hydrophobic electrospun membrane for 3D cell culture

    , Article Biomedical Microdevices ; Volume 19, Issue 4 , 2017 ; 13872176 (ISSN) Moghadas, H ; Saidi, M. S ; Kashaninejad, N ; Kiyoumarsioskouei, A ; Trung Nguyen, N ; Sharif University of Technology
    This paper reports the fabrication of electrospun polydimethylsiloxane (PDMS) membranes/scaffolds that are suitable for three-dimensional (3D) cell culture. Through modification the ratio between PDMS and polymethylmethacrylate (PMMA) as carrier polymer, we report the possibility of increasing PDMS weight ratio of up to 6 for electrospinning. Increasing the PDMS content increases the fiber diameter, the pore size, and the hydrophobicity. To our best knowledge, this is the first report describing beads-free, durable and portable electrospun membrane with maximum content of PDMS suitable for cell culture applications. To show the proof-of-concept, we successfully cultured epithelial lung... 

    Electrokinetic Flow in pH-Regulated Solid-State/Soft Micro-Nanochannels

    , Ph.D. Dissertation Sharif University of Technology Sadeghi, Morteza (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Mousavi, Ali (Co-Supervisor) ; Sadeghi, Arman (Co-Supervisor)
    In recent years, advances have been made in the field of miniaturization of the devices (in order to increase their efficiency, lessen the materials needed for the constructions and experiments, reduce costs and energy usage) resulting in the dramatic increase of surface to volume ratio in these devices. This progress has led to the dominance of surface forces which can be used to control very important interface phenomena having a special application such as electrokinetic. Using today’s manufacturing technology; it is possible to construct micro-nanochannels made from different materials such as silicon, glass, quartz, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) whose... 

    Engineering of mature human induced pluripotent stem cell-derived cardiomyocytes using substrates with multiscale topography

    , Article Advanced Functional Materials ; Volume 28, Issue 19 , 2018 ; 1616301X (ISSN) Pour Shahid Saeed Abadi, P ; Garbern, J. C ; Behzadi, S ; Hill, M. J ; Tresback, J. S ; Heydari, T ; Ejtehadi, M. R ; Ahmed, N ; Copley, E ; Aghaverdi, H ; Lee, R. T ; Farokhzad, O. C ; Mahmoudi, M ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Producing mature and functional cardiomyocytes (CMs) by in vitro differentiation of induced pluripotent stem cells (iPSCs) using only biochemical cues is challenging. To mimic the biophysical and biomechanical complexity of the native in vivo environment during the differentiation and maturation process, polydimethylsiloxane substrates with 3D topography at the micrometer and sub-micrometer levels are developed and used as cell-culture substrates. The results show that while cylindrical patterns on the substrates resembling mature CMs enhance the maturation of iPSC-derived CMs, sub-micrometer-level topographical features derived by imprinting primary human CMs further accelerate both the... 

    Plasma based surface modication of poly (dimethylsiloxane) electrospun membrane proper for organ-on-a-chip applications

    , Article Scientia Iranica ; Volume 26, Issue 2 , 2019 , Pages 808-814 ; 10263098 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Moghadas, H ; Firoozabadi, B ; Sharif University of Technology
    Sharif University of Technology  2019
    Electrospun porous membrane; Superhydrophilic surfaces; Superhydrophobic surfaces; Cell culture; Organ on a chip; Flexible membrane; Strong membrane; Surface modications  

    Plasma based surface modication of poly (dimethylsiloxane) electrospun membrane proper for organ-on-a-chip applications

    , Article Scientia Iranica ; Volume 26, Issue 2 , 2019 , Pages 808-814 ; 10263098 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Moghadas, H ; Firoozabadi, B ; Sharif University of Technology
    Sharif University of Technology  2019
    onstructing of the scaffolds for cell culture applications has long been of interest for engineering researchers and biologist. In this study, a novel process is utilized for construction of suitable membrane with a high mechanical strength and appropriate surface behavior. Poly (dimethylsiloxane) (PDMS) is electrospun into fine fibers using poly (methyl methacrylate) (PMMA) as the carrier polymer in different weight ratios. Since the surface behavior of all PDMS substrates is moderately hydrophobic (120 < contact angle (CA) < 150), the electrospun membranes with higher PDMS ratios show slightly higher hydrophilicity. Direct plasma treatment is utilized to change the interfacial wettability... 

    In situ solid-phase microextraction and post on-fiber derivatization combined with gas chromatography-mass spectrometry for determination of phenol in occupational air

    , Article Analytica Chimica Acta ; Volume 742 , 2012 , Pages 17-21 ; 00032670 (ISSN) Es haghi, A ; Baghernejad, M ; Bagheri, H ; Sharif University of Technology
    Elsevier  2012
    A method based on solid-phase microextraction (SPME) followed by on-fiber derivatization and gas chromatography-mass spectrometry detection (GC-MS) for determination of phenol in air was developed. Three different types of SPME fibers, polar and non-polar poly(dimethylsiloxane) (PDMS) and polyethylene glycol (PEG) were synthesized using sol-gel technology and their feasibility to the sampling of phenol were investigated. Different derivatization reagents for post on-fiber derivatization of phenol were studied. Important parameters influencing the extraction and derivatization process such as type of fiber coating, type and volume of derivatizing reagent, derivatization time and temperature,...