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Functionalization methods of carbon fibers – an overview

Magdziarz Sylwia, Frączyk Justyna, Boguń Maciej

Polimery

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2023

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Vol. 68, nr 6

307--316

EN

This article is a literature review related to the methods of functionalization of carbon fibers for tissue engineering applications. Through physical modification, it is possible to obtain a layer of a chemical compound on the carbon fibers surface and to impart additional properties. On the other hand, chemical modification may lead to the incorporation of appropriate functional groups into the carbon fiber structure, capable of attaching, among others, biologically active compounds. The paper presents the advantages and disadvantages of the carbon fibers modifying methods, with particular emphasis on the use of such modified fibers in medicine.

PL

Niniejsza praca stanowi przegląd literatury dotyczący metod funkcjonalizacji włókien węglowych przeznaczonych do zastosowań w inżynierii tkankowej. Poprzez modyfikację fizyczną możliwe jest uzyskanie warstwy związku chemicznego na powierzchni włókien węglowych i nadanie im dodatkowych właściwości. Natomiast modyfikacja chemiczna może prowadzić do wbudowania w strukturę włókna węglowego odpowiednich grup funkcyjnych zdolnych do przyłączania m.in. związków aktywnych biologicznie. W pracy przedstawiono zalety i wady stosowanych metod modyfikacji włókien węglowych, ze szczególnym naciskiem na zastosowanie tak modyfikowanych włókien w medycynie.

2

Cost-effective titania layers over 100 nm thick : effect of annealing on the structural, morphological, and optical properties

Zięba Magdalena, Tyszkiewicz Cuma, Gondek Ewa, Wojtasik Katarzyna, Nizioł Jacek, Dorosz Dominik, Starzyk Bartłomiej, Szymczak Patryk, Pakieła Wojciech, Rogoziński Roman, Karasiński Paweł

Opto-Electronics Review

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2023

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Vol. 31, No. 4

art. no. e147913

EN

Titania dioxide (TiO₂) layers were synthesized via the acid-catalysed sol-gel route using titania (IV) ethoxide, and then annealed at temperatures varying in the range of 150-700 °C. The research concerned the effect of annealing temperature on the structure of TiO₂ layers, their surface morphology, and their optical properties. Further, X-ray diffractometry, and Raman spectroscopy were used to determine the structure of TiO₂ layers. Scanning electron and atomic force microscopy were used to study the surface morphology of TiO₂ layers. Transmittance, reflectance, absorption edge, and optical homogeneity were investigated by UV-VIS spectrophotometry, while the refractive index and thicknesses of TiO₂ layers were measured using a monochromatic ellipsometer. Chromatic dispersion characteristics of the complex refractive index were determined using spectroscopic ellipsometry. Structural studies have shown that the TiO₂ layers annealed at temperatures up to 300 °C are amorphous, while those annealed at temperatures exceeding 300 °C are polycrystalline containing only anatase nanocrystals with sizes increasing from 6 to 20 nm with the increase of the annealing temperature. Investigations on the surface morphology of TiO₂ layers have shown that the surface roughness increases with the increase in annealing temperature. Spectrophotometric investigations have shown that TiO₂ layers are homogeneous and the width of the indirect optical band gap varies with annealing temperature from 3.53 eV to 3.73 eV.

3

Jedno- i dwuwarstwowe struktury antyrefleksyjne wytwarzane metodą zol-żel do zastosowań w fotoogniwach krzemowych

Skolik M., Karasiński P.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 8

73--76

PL

Pomimo pojawienia się wielu nowych rodzajów fotoogniw słonecznych, fotogniwa krzemowe nadal odgrywają istotną rolę. Wysoki współczynnik załamania krzemu sprawia, że ponad 34% fotonów promieniowania słonecznego z zakresu absorpcji krzemu ulega od niego odbiciu i nie generuje w nim ekscytonów. Odbicie światła można istotnie zmniejszyć teksturując powierzchnię krzemu, wytwarzając na niej strukturę antyrefleksyjną albo stosując jednocześnie oba rozwiazania. Praca dotyczy jedno- i dwuwarstwowych struktur antyrefleksyjnych wywtarzanych metodą zol-żel i techniką dip-coating na podłożach krzemowych. Dla struktury jednowarstwowej osiągnięto ważony współczynnik odbicia fotonów Rw 9%, natomiast dla struktury dwuwarstwowej osiągnięto Rw<4%. W pracy przedstawiano optymalizację teoretyczną struktur antyrefleksyjnych, technologię ich wytwarzania oraz wyniki badań eksperymentalnych. Osiągnięto doskonałą zgodność wyników analizy teoretycznej z wynikami eksperymentalnymi.

EN

Besides many different types of photovoltaic solar cells, silicon solar cells are still of significant importance. Bare silica’s high refraction index leads to greater than 34% reflection of solar light photones, within silica’s absorption band, from its surface without generating excitons. Reflection loss can be significantly reduced with the use of surface texturing and/or antireflective coatings. The most beneficial effect is achieved when combinig both, surface texturing and antireflective coatings. This work presents single and double layer Anti Reflective Structures (ARS’s) derived from sol-gel process for application in silicon photovoltaic cells. Weighted average reflection of a single layer ARS is Rw 9%, whereas double layer ARS provides weighted average reflection Rw<4%. In this work theoretical optimization of ARS’s, technological process of structure fabrication as well as experimental results are demonstrated. Theoretical data shows excellent correlation with experimental results.

4

Porównanie grubości warstw materiału uzyskanego podczas przejścia zol-żel (metodą dip-coating) na podłożach wyciąganych z wodnych roztworów spoiw koloidalnych

Wawrylak M., Leśniewski W., Szczepaniak-Lalewicz K.

Prace Instytutu Odlewnictwa

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2014

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T. 54, nr 4

43--50

PL

W artykule zaprezentowano metodę badania przejścia zol-żel, w której płytki odpowiedniego podłoża są wyciągane z wodnego spoiwa koloidalnego ze stałą prędkością. Grubość naniesionej warstwy jest związana z wielkością cząstek występujących w spoiwie. Przydatność technologiczna spoiw koloidalnych ograniczona agregacją cząstek jest trudna do oceny bez dostępu do specjalistycznych urządzeń pomiarowych. Opracowanie prostej metody umożliwiającej szybką ocenę parametrów użytkowych spoiwa koloidalnego może znaleźć zastosowanie w praktyce przemysłowej.

EN

This paper presents the method of investigating the sol-gel transition by constant speed removal of plates, made of suitable substrate, from an aqueous colloidal binder. The thickness of the deposited colloidal binder layer depends on the particle sizes in the binder. The processing feasibility of colloidal binders reduced by aggregation of particles is difficult to evaluate without access to special measuring equipment. Development of a simple method for prompt evaluation of performance parameters in colloidal binders may have industrial applications.

5

A comparative study of dip coating and spray pyrolysis methods for synthesizing ITO nanolayers by using Ag colloidal sol

Rajabi N, Heshmatpour F, Malekfar R, Bahari-Poor H R, Abyar S

Materials Science Poland

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2014

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Vol. 32, No. 1

102--106

EN

Indium tin oxide (ITO) films were deposited on glass substrates by dip-coating and thermal pyrolysis methods. Sn (IV) is often used in the spray method as a precursor salt, but in this research we have employed a new procedure that uses Sn (II) and In(NO3)3 for preparation of transparent conductive thin films. Then, colloidal Ag was deposited on the ITO layers in order to compare the two synthesis methods, and the structural and electrical properties of the resultant films were investigated by FESEM, XRD, and four-terminal resistometry. The obtained films are polycrystalline with a preferred orientation of (200). The XRD patterns of the films indicate that in both films, the Sn phase is crystallized separately from In2O3. The presence of a Sn peak and the overall low intensity of XRD peaks suggest relative crystallization of ITO structure. For this reason, Ag films were deposited by dip coating method using a colloidal sol. By analyzing the XRD patterns of Ag-ITO films after eliminating the Sn peak, the increased intensity of the peaks confirmed the relatively good crystallization of the ITO films. The results show that the films with a sheet resistance as low as 2 × 10-2 W cm, which is beneficial for solar cells, were achieved.

6

Surface Morphology of Polyimide Thin Film Dip-Coated on Polyester Filament for Dielectric Layer in Fibrous Organic Field Effect Transistor

Rambausek L., Bruneel E., Van Driessche I., Van Langenhove L.

Autex Research Journal

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2014

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Vol. 14, no. 3

152--160

EN

The idea of wearable electronics automatically leads to the concept of integrating electronic functions on textile substrates. Since this substrate type implies certain challenges in comparison with their rigid electronic companions, it is of utmost importance to investigate the application of materials for generating the electronic functions on the textile substrate. Only when interaction of materials and textile substrate is fully understood, the electronic function can be generated on the textile without changing the textile’s properties, being flexible or stretchable. This research deals with the optimization of the dielectric layer in a fibrous organic field effect transistor (OFET). A transistor can act as an electrical switch in a circuit. In this work, the polyimide layer was dip-coated on a copper-coated polyester filament. After thoroughly investigating the process conditions, best results with minimal thickness and roughness at full insulation could be achieved at a dip-coating speed of 50 mm/min. The polyimide solution was optimal at 15w% and the choice for the solvent NMP was made. In this paper, details on the pre-treatment methods, choice of solvent and dip-coating speed and their effect on layer morphology and thickness, electrical properties and roughness are reported. Results show that the use of polyimide as a dielectric layer in the architecture of a fibrous OFET is promising. Further research deals with the application of the semiconductor layer within the mentioned architecture, to finally build an OFET on a filament for application in smart textiles.

7

Polyimide Dielectric Layer on Filaments for Organic Field Effect Transistors: Choice of Solvent, Solution Composition and Dip-Coating Speed

Rambausek L., Bruneel E., De Mey G., Van Langenhove L.

Autex Research Journal

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2014

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Vol. 14, no. 3

121-134

EN

In today’s research, smart textiles is an established topic in both electronics and the textile fields. The concept of producing microelectronics directly on a textile substrate is not a mere idea anymore and several research institutes are working on its realisation. Microelectronics like organic field effect transistor (OFET) can be manufactured with a layered architecture. The production techniques used for this purpose can also be applied on textile substrates. Besides gate, active and contact layers, the isolating or dielectric layer is of high importance in the OFET architecture. Therefore, generating a high quality dielectric layer that is of low roughness and insulating at the same time is one of the fundamental requirements in building microelectronics on textile surfaces. To evaluate its potential, we have studied polyimide as a dielectric layer, dip-coated onto copper-coated polyester filaments. Accordingly, the copper-coated polyester filament was dip-coated from a polyimide solution with two different solvents, 1-methyl-2-pyrrolidone (NMP) and dimethylformaldehyde. A variety of dip-coating speeds, solution concentrations and solvent-solute combinations have been tested. Their effect on the quality of the layer was analysed through microscopy, leak current measurements and atomic force microscopy (AFM). Polyimide dip-coating with polyimide resin dissolved in NMP at a concentration of 15w% in combination with a dip-coating speed of 50 mm/min led to the best results in electrical insulation and roughness. By optimising the dielectric layer’s properties, the way is paved for applying the subsequent semi-conductive layer. In further research, we will be working with the organic semiconductor material TIPS-Pentacene.

8

Influence of the coating process parameters on the quality of PUR/PVP hydrogel coatings for PVC medical devices

Paradowska A., Kaźmierska K., Ciach T.

Polish Journal of Chemical Technology

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2010

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Vol. 12, nr 2

38-45

EN

To decrease friction factor and enhance the biocompatibility of medical devices manufactured from poly(vinyl chloride), PVC, the surface modification with wear resistant polyurethane/polyvinylpyrrolidone (PUR/PVP) hydrogel coating can be applied. In the present work substrates were dip-coated with PVP and PUR solutions and thermally cured. The variable process parameters were: solvent system; concentration of polymers (1, 2 or 3% w/v); coating baths temperature (22, 38 and 55°C); drying temperature (32, 50 and 67°C); length of break between process steps (5, 30 and 90 s); and solutions storage time (up to 72 hrs). The quality of coatings was determined by friction coefficients against porcine aorta, weights of the deposited layer and the swelling capacity. The solvent system and polymers concentration were crucial factors. The increased temperature of coating solutions caused increased deposition but decreased durability. The most lubricious samples were dried in 50oC. Coatings from the solutions prepared 24h prior to use had better properties than those from fresh solutions.

9

Photoluminescence of poly(N-vinylcarbazole) thin films deposited by dip-coating technique

Rębarz M., Dalasiński P., Bała W., Łukasiak Z., Wojdyła M., Kreja L.

Optica Applicata

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2005

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Vol. 35, nr 3

407-412

EN

This paper is concerned with the photoluminescence (PL) study of poly(N-vinylcarbazole) (PVK) thin films deposited on the glass substrate by the dip-coating method. The PL spectra have been measured under steady state excitation (He-Cd laser, 325 nm) in the temperature range from 13 to 300 K. All the samples being studied exhibit strong luminescence in broad temperature range. The main emission PL peak has maximum at 410 nm and is attributed to the excimer emission of PVK. We have observed a small red-shift of this peak with an increase of temperature. In all the films under investigation the thermal quenching of PL has been noticed. This behaviour is determined by the closeness of carbazole groups belonging to neighbouring chains because the interaction between them leads to nonradiative transitions. The PL spectra of PVK thin films annealed under iodine atmosphere have also been investigated. We have observed a decrease of PL for these films. We have concluded that the annealing of PVK under iodine atmosphere induces its degradation.

10

Metoda wytwarzania wielowarstwowej ceramiki porowatej

Puff Z., Raabe J., Bobryk E.

Kompozyty

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2003

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R. 3, nr 8

444--449

PL

Ceramiczne elementy filtracyjne posiadające kształt rur jedno- i wielokanałowych są materiałami wielowarstwowymi składającymi się z podłoża (o wielkości porów 5--10 [mikro]m) i warstw filtracyjnych nakładanych na wewnętrzną powierzchnię kanałów. W przypadku warstwy mikrofiltracyjnej wielkość jej ziaren jest kilkanaście razy mniejsza od wielkości porów podłoża i ziarna te podczas nakładania warstwy mogą wnikać w głąb podłoża, zwiększając opory przepływu (rys. 2). Zwiększone opory przepływu utrudniają filtrację, szczególnie w wielokanałowych elementach filtracyjnych, w których droga przepływu przesączu jest znacznie wydłużona (rys. 3). Podjęte badania miały na celu wyeliminowanie zjawiska wzajemnego przenikania warstw o różnej granulacji ziaren podczas bezpośredniego nakładania warstwy mikrofiltracyjnej metodą zanurzeniową (rys. 4) na makroporowate podłoże bez stosowania warstw pośrednich. Zastosowano dwie metody "blokowania" przenikania warstw o znacznie różniącej się wielkości tworzących je ziaren: przez nasycanie makroporowatego podłoża zolem akrylamidu oraz przez dodatek tego zolu do gęstwy używanej do nakładania warstwy mikrofiltracyjnej metodą zanurzeniową. W pierwszym przypadku nie uzyskano oczekiwanego efektu, ponieważ zaobserwowano zjawisko zasysania drobnych ziaren warstwy mikrofiltracyjnej do wnętrza podłoża (rys. 7a). Dobre wyniki uzyskano przy pokrywaniu makroporowatego podłoża gęstwą z drobnoziarnistego proszku, zawierającej w swoim składzie (w odpowiednich proporcjach) roztwór wodny alkoholu poliwinylowego i zol akrylamidu, powodujący "blokowanie" możliwości przenikania drobnoziarnistego proszku do wnętrza podłoża (rys. 7b).

EN

Ceramic filtering elements in the shape of single- or multi-channel pipes are multilayer materials composed of the substrate (with pore size of 5--10 [micro]m) and filtering layers applied on the inner surface of channels. As for the microfiltering layer, its grains are more than ten times smaller than the size of substrate pores, and when the layer is applied, these grains may penetrate into the substrate, and increase the flow resistance (Fig. 2). The increased flow resistance obstructs the fiitration, especially in multi-channel filtering elements, in which the filtrate flows along a significantly elongated route (Fig. 3). The research was undertaken to eliminate the phenomenon of mutual penetration of layers with varied grain sizes, when the microfiltration layer is applied directly using the dip-coating method (Fig. 4) on the macro-porous substrate, with no intermediatc layers used. Two methods were used to "block" penetration of layers with significantly different grain sizes: saturation of the macro-porous substrate with acrylamide sol and adding that soi to the slurry used in the dip-coating method to apply the microfiltration layer. In the first case the expected effect was not detected, as the tiny grains were sucked into the substrate interior (Fig. 7a). Good results were obtained when the macro-porous substrate was covered with the slurry made of fine-grain powder (d ~ 0.5 [micro]m) of YSZ, composed of an adequate proportion of water solution of polyvinyl alcohol and acrylamide sol, which causes "blockage" of the potential penetration of the fine-grain powder into the substrate interior (Fig. 7b).