Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Research Project Darbe altında ışıma yapan polimerik filmler ve lif demetlerinin üretilmesi ve uygulamaları(2016) Demir, Mustafa M.; İncel, AnılTribolüminesans (TL) malzemeler darbe altında ışıma özelliğine sahip kristal yapılardır. Bu projede, organik ve metal yapıları bir arada bulunduran iki TL kristal (EuD4TEA ve Cu(NCS)(py)2(PPh3)) elde edilmiş ve mikrometre büyüklüğündeki tanecikler PMMA (poli metil metakrilat), PS (polistiren), PU (poliüretan) ve PVDF (polivinilflorür) saydam özellikteki polimerler kullanılarak ince-katmanlı film, elektrospun lif demetleri ve nano boyutundaki tanecikler elde edilen matrisler ile entegre edilmiştir. Kompozit malzemelerin elde edilmesi için iki farklı deneysel metod geliştirilmiştir: i) yükleme işlemi ve ii) yüzeye depolama işlemi. Kompozit malzemelerin TL performansları bu tez için özel tasarlanan atış kule sistemi ile ölçülmüştür. Bunun yanı sıra, atomik kuvvet mikroskobu (AFM), taramalı elektron mikroskobu (SEM) polimerlerin ve kompozit malzemelerin topografik ve morfolojik özellklerini değerlendirmek için kullanılmıştır. Ayrıca, flüoresans mikroskobu kullanılarak kompozit malzemelerin emisyon sırasındaki renk sinyalleri belirlenmiştir. Son olarak piezoelektrik özellikleri osiloskop kullanılarak belirlenmiştir. Tüm bu cihazlardan elde edilen sonuçlar değerlendirildiğinde, deneysel prosedür, kristal taneciklerin boyutları, polimer malzemenin formu ve yüzey özelliği, kullanılan kristallerin kompozit içindeki miktarı bu çalışmada temel parametreler olarak belirlenmiştir. PU esaslı elde edilen film ve lif demeti kompozitler PMMA, PS, ve PVDF esaslı kompozitlerden daha iyi sonuç göstermiştir. Bunun nedeni olarak, film esaslı kompozitler için ince katmanlı PU filmin daha engebeli ve saydam bir yüzey olması; lif esaslı kompozitler için elektrospun PU liflerin daha küçük yapılardan oluşması, tüm bunlara ek olarak PU’nın kimyasal olarak TL özellikteki iki kristalle kimyasal etkileşim oluşturulması gösterilebilir.Article Citation - WoS: 4Citation - Scopus: 4Triboluminescent Composite Microspheres Consisting of Alginate and Eud(4)tea Crystals(Elsevier, 2018) İncel, Anıl; Demir, Mustafa MuammerAlginate is utilized to obtain luminescent composite microspheres containing europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) triboluminescent (TL) crystals. Na alginate is initially treated with Ca(II) and then Eu (III) so that physically-crosslinked alginate microspheres were obtained. EuD4TEA crystals are precipitated in situ on the surface of the spheres upon treatment with dibenzoylmethane (DBM) and triethylamine (TEA). The EuD4TEA/alginate composite spheres are swollen in aqueous system, the diameter of the microspheres increases from 180 up to 405 pm in 48 h. TL intensity of the spheres swollen in 1 h decreases 4 folds compared to dry spheres; however, it systematically increases as the swelling time is extended step-wise to 48 h. Swelling may develop structural homogenity in the microsphere that supresses the optical scattering and may lead to better transmittance of the TL signal. (C) 2017 Elsevier B.V. All rights reserved.Article Citation - WoS: 44Citation - Scopus: 53Smart Phone Assisted Detection and Quantification of Cyanide in Drinking Water by Paper Based Sensing Platform(Elsevier Ltd., 2017) İncel, Anıl; Akın, Osman; Çağır, Ali; Yıldız, Ümit Hakan; Demir, Mustafa MuammerAn organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12 M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.Article Citation - WoS: 15Citation - Scopus: 21Triboluminescent Electrospun Mats With Blue-Green Emission Under Mechanical Force(American Chemical Society, 2017) İncel, Anıl; Varlıklı, Canan; McMillen, Colin D.; Demir, Mustafa MuammerFibrous mechanosensing elements can provide information about the direction of crack propagation and the mechanism of material failure when they are homogeneously dispersed into the bulk volume of materials. A fabrication strategy of fibrous systems showing triboluminescent (TL) responses is in high demand for such applications. In this work, micrometer-sized Cu(NCS)(py)2(PPh3) crystals were synthesized, and polymeric fibrous mats containing the TL crystals were obtained via electrospinning as a stress probe for the determination of mechanical impact. Four different polymeric systems have been employed (PMMA, PS, PU, and PVDF), and the mechano-optical sensing performance of electrospun mats of the polymer-crystal composites was measured. Photophysical properties (quantum yield, band gap, and broadness of the emission) of the TL crystal/electrospun mat composites were also studied. TL and PL emission maxima of the PU-based composite mat show identical behavior due to the chemical affinity between the two structures and the smallest fiber diameter. Moreover, the PU fiber mats exhibit long-lived bluish-green emission persisting over a large number of drops.Article Citation - WoS: 31Citation - Scopus: 36Integration of Triboluminescent Eud4tea Crystals To Transparent Polymers: Impact Sensor Application(American Chemical Society, 2017) İncel, Anıl; Eanes, Mehtap; McMillen, Colin D.; Demir, Mustafa MuammerLanthanide-based organometallic materials are well-known candidate triboluminescent (TL) materials that can show bright emission when a mechanical force is applied. These materials are usually in the form of crystalline powders, and it is often useful to integrate these samples into a polymer matrix in order to achieve processability, enabling coating from a solution/molten state or fabrication as a complex-shaped matrix. In this work, micrometer-sized europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) crystals were synthesized and integrated with various transparent polymers (PMMA, PS, PVDF, and PU) using two approaches: (i) blending and (ii) surface impregnation. In the former method, the crystalline particles were molecularly dissolved; therefore, a TL response cannot be achieved. More than 10 wt % TL crystals in the composite is needed to obtain TL signals. However, TL signal was achieved at 2.5 wt % when a composite was prepared by the latter approach. TL intensity shows exponential decay with consecutive mechanical action. The TL emission of PU-based surface impregnated composite expires with long-lived emission, and maximum TL response with respect to applied force was measured between 2.45 and 42.0 N.Article Citation - WoS: 8Citation - Scopus: 9A New Method To Extend the Stress Response of Triboluminescent Crystals by Using Hydrogels(Elsevier Ltd., 2017) İncel, Anıl; Reddy, Subrayal M.; Demir, Mustafa MuammerPolyacrylamide hydrogel entrapment of EuD4TEA or Cu(NCS)(py)2(PPh3) radically extends the emission time of the triboluminescent (TL) crystalline particles by a factor of 103, optimized when matching the hydrophilic/hydrophobic characteristics of the TL/gel components. Triboluminescence intensity improves with hydration of the TL/hydrogel composite. The composites may be used in impact-related sensor applications.Article Citation - WoS: 22Citation - Scopus: 25Null Extinction of Ceria@silica Hybrid Particles: Transparent Polystyrene Composites(American Chemical Society, 2015) İncel, Anıl; Güner, Tuğrul; Parlak, Onur; Demir, Mustafa MustafaScattering of light in optical materials, particularly in composites based on transparent polymer and inorganic pigment nanoparticles, is a chronic problem. It might originate mainly from light scattering because of a refractive index mismatch between the particles and transparent polymer matrix. Thus, the intensity of light is rapidly diminished and optical transparency is reduced. Refractive index matching between the pigment core and the surrounding transparent matrix using a secondary component at the interface (shell) has recently appeared as a promising approach to alter light scattering. Here, CeO2 (ceria) nanoparticles with a diameter of 25 nm are coated with a SiO2 (silica) shell with various thicknesses in a range of 6.5-67.5 nm using the Stöber method. When the hybrid core-shell particles are dispersed into transparent polystyrene (PS), the transmission of the freestanding PS composite films increases over both the ultraviolet (UV) and visible region as the shell thickness increases particularly at 37.5 nm. The increase of transmission can be attributed to the reduction in the scattering coefficient of the hybrid particles. On the other hand, the particles in tetrahydrofuran (THF) absorb over UV and the intensity of absorption shows a systematic decrease as the shell thickness increases. Thus, the silica shell suppresses not only the scattering coefficient but also the molar absorptivity of the core ceria particles. The experimental results regarding the target shell thickness to develop low extinction (scattering + absorption) composites show a qualitative agreement with the predictions of Effective Medium Theory.