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81 results on '"Knez, Mato"'

8. In Situ Investigation of Thermally Induced Surface Graphenization of Polymer-Derived Ceramic (PDC) Coatings from Molecular Layer (MLD) Deposited Silicon-Based Preceramic Thin Films

Author

Ashurbekova, Kristina, primary, Modin, Evgeny, additional, Hano, Harun, additional, Ashurbekova, Karina, additional, Saric Jankovic, Iva, additional, Peter, Robert, additional, Petravić, Mladen, additional, Chuvilin, Andrey, additional, Abdulagatov, Aziz, additional, and Knez, Mato, additional

Published
2023
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16. Nanoscale engineering omniphobic surfaces

Author

Palenzuela Conde, Jesús, Knez, Mato, Pitarke de la Torre, José María, Polímeros y Materiales Avanzados: Física, Química y Tecnología, Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Fenero Bisquer, Marta, Palenzuela Conde, Jesús, Knez, Mato, Pitarke de la Torre, José María, Polímeros y Materiales Avanzados: Física, Química y Tecnología, Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, and Fenero Bisquer, Marta

Abstract

Capítuldo 5 confidencial pendiente de patente. Tesis completa 159 p. Tesis censurada 143, [ES]Las superficies expuestas al ambiente presentan una gran tendencia a atraer suciedad. Teniendo en cuenta que son éstas las que definen la mayor parte de las propiedades de los materiales, tanto la presencia como la acumulación de suciedad suponen un impacto negativo en numerosas aplicaciones ya que pueden generar importantes riesgos para la seguridad y la salud, así como, afectar negativamente al rendimiento, requiriendo costosas operaciones de mantenimiento. En los últimos años, la industria ha mostrado un gran interés en el desarrollo de soluciones capaces de preservar limpias las superficies. Tradicionalmente, las superficies repelentes se han obtenido mediante el efecto de la superhidrofobicidad. Sin embargo, su ineficacia para repeler líquidos de baja energía superficial y la fragilidad de ciertas micro/nanoestructuras necesarias pueden limitar su aplicación. En este contexto, el desarrollo de recubrimientos omnifóbicos de baja adhesión puede aportar numerosos beneficios en distintas aplicaciones de sectores muy diversos. Esta tesis persigue desarrollar nuevas estrategias para la obtención de superficies repelentes, focalizando el trabajo en alcanzar soluciones robustas con buenas prestaciones de durabilidad que sean capaces de responder a varias fuentes de contaminación simultáneamente. Para ello, el potencial que ofrece la nanotecnología se utiliza desde dos aproximaciones diferentes: a través de la estructuración superficial ymediante la incorporación de nanoobjetos como vectores para introducir nuevas funcionalidades, siendo el objetivo final desarrollar superficies omnifóbicas con propiedades diseñadas a medida que den respuesta a las necesidades de la industria.

Published
2023

17. Bio-inspired light radiating, air circulating and expanding mechanisms

Author

Knez, Mato, Lakhtakia, Akhlesh, J. Martín-Palma, Raúl, G. U. Boizumaulta, Lilie, Lenau, Torben A., J. Smoraczewska Harris, Ella, Simsek, Gizem, Knez, Mato, Lakhtakia, Akhlesh, J. Martín-Palma, Raúl, G. U. Boizumaulta, Lilie, Lenau, Torben A., J. Smoraczewska Harris, Ella, and Simsek, Gizem

Abstract

This paper explores how Biologically Inspired Design (BID) can be applied in the development of medical devices through a concrete case study. Nature has been developing, over the last 3.8 billion years, the most efficient mechanisms to fulfil a function and overcome challenges. Based on this giant innovation database, BID has received an exponential increase of interest since the 1950s and has led to innovative solutions in a vast variety of fields. The present study is motivated by a medical device which should be designed for insertion in a cavity, followed by a significant expansion inside the cavity. Once expanded, the device should be able to radiate light for disinfection purposes, while simultaneously allowing air replacement in the cavity. Finally, the device should contract to its original size before being extracted from the cavity. In order to propose radically new ideas for designing such a device, BID is applied to a range of functions namely i) how to expand an object after insertion in a cavity, ii) how to promote air circulation in the cavity, iii) how to radiate light to all surfaces in the cavity and finally iv) how to contract the object again. This paper presents and discusses the BID process as well as the outcomes of this study. 25 biological strategies have been identified throughout the project, 7 ideas were generated and 4 more detailed concepts and physical mock-ups emerged from these ideas. 2 of them were considered interesting for further development, which indicates a good efficacy of the process. The whole study lasted 32 working days, suggesting a high efficiency of the BID process.

Published
2023

18. Biocompatible Silicon-Based Hybrid Nanolayers for Functionalization of Complex Surface Morphologies

Author

Ashurbekova, Karina, Ashurbekova, Kristina, Alonso-Lerma, Borja, Šarić, Iva, Barandiaran, Leire, Modin, Evgeny, Petravić, Mladen, Perez-Jimenez, Raul, and Knez, Mato

Subjects
ring-opening, molecular layer deposition, alumosilazane, alumosiloxane, organosilicon, biocompatible films, human embryonic kidney (HEK293T) cells, thin film, hybrid, General Materials Science
Abstract

Silicon-based polymers show great promise for various applications in biomedicine, nanotechnology, tissue targeting, and drug delivery. The use of such materials as functional coatings on surfaces requires the development of strongly adhering and flexible conformal films, which is challenging for conventional wet-chemical coating techniques. We have developed a facile, solvent-free molecular layer deposition (MLD) process to grow environmentally stable hybrid alumosilazane thin films. Exceptionally good biocompatibility is testified with significantly higher proliferation of human embryonic kidney (HEK293T) cells than that on glass, which was used as a reference. Such highly biocompatible and conformal films show great promise as functional coatings for scaffolds or implantable devices with complex topologies or high-aspect-ratio structures.

Published
2022
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21. In SituInvestigation of Thermally Induced Surface Graphenization of Polymer-Derived Ceramic (PDC) Coatings from Molecular Layer (MLD) Deposited Silicon-Based Preceramic Thin Films

Author

Ashurbekova, Kristina, Modin, Evgeny, Hano, Harun, Ashurbekova, Karina, Saric Jankovic, Iva, Peter, Robert, Petravić, Mladen, Chuvilin, Andrey, Abdulagatov, Aziz, and Knez, Mato

Abstract

The in situfree carbon formation in polymer-derived ceramics (PDCs) is essential for its microstructure evolution and resulting unique characteristics. This study advances the phenomenon of surface graphenization with the first silicon-based conformal preceramic polymer thin films deposited by molecular layer deposition (MLD). In situthermal annealing transmission electron microscopy (TEM) investigation was performed to study the evolution of carbon on the nanoscale during high-temperature postprocessing of the hybrid organic–inorganic siloxane–alumina (SiAlCHO) in vacuum. The e-beam exposure during annealing induced the knock-on damage process, i.e., direct displacement/emission of an atom as a result of the collision with a fast electron. The emission of hydrogen atoms of the preceramic MLD film led to a loss of hydrogen from the organic groups within the film, which determined the first stage of the observed phenomenon, the carbonization of the film. The relatively high annealing temperature of the sample provided the carbon mobility to form an energetically favorable sp2-bonding arrangement of carbon, which led to the formation of up to four graphene layers. The amount of carbon in the preceramic SiAlCHO, which is the source for the graphene layer formation, and consequently the resulting number of surficial graphene layers can be reduced by increasing the MLD process temperature so that it forms even a single layer. Micro-Raman mapping was performed to confirm the chemical nature of the e-beam-induced graphene formation. The resulting SiAlCO PDCs withstand annealing temperatures as high as 1200 °C without crystallization and phase separation. The investigation allows for a better understanding of the microstructural evolution of carbon in the near-surface region and its associated properties, which are essential for various applications of PDCs.

Published
2023
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46. Conductive Polymer–Inorganic Hybrid Materials through Synergistic Mutual Doping of the Constituents

Author

Wang, Weike, Chen, Chaoqiu, Tollan, Christopher, Yang, Fan, Beltrán, Mikel, Qin, Yong, and Knez, Mato

Abstract

Polymer-matrix-based inorganic–organic hybrid materials are at the cutting edge of current research for their great promise of merging properties of soft and hard solids in one material. Infiltration of polymers with vapors of reactive metal organics is a pathway for postsynthetic blending of the polymer with inorganic materials. Here, we show that this process is also an excellent method for fabricating conductive hybrid materials. Polyaniline (PANI) was infiltrated with ZnO and the initially insulating polymer was converted to a PANI/ZnO hybrid with conductivities as high as 18.42 S/cm. The conductivity is based on a synergistic effect of the constituting materials, where the inorganic and the polymeric fractions mutually act as dopants for the counterpart. The process temperature is a very important factor for successful infiltration, and the number of applied infiltration cycles allows tuning the level of conductivity of the resulting PANI/ZnO.

Published
2024
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47. Laponite-Based Surfaces with Holistic Self-Cleaning Functionality by Combining Antistatics and Omniphobicity

Author

Fenero, Marta, Palenzuela, Jesús, Azpitarte, Itxasne, Knez, Mato, Rodríguez, Javier, and Tena-Zaera, Ramón

Abstract

In the present work, perfluoroalkylated laponite nanoparticles with a high degree of functionalization (60 wt %) have been prepared and a methodology to prepare transparent, antistatic, and omniphobic laponite-based films with holistic self-cleaning properties against liquids, solids and liquid–solid mixtures has been developed. The intrinsic electrical and ionic conductivities observed in unmodified laponite coatings are combined with perfluoroalkyl-modified laponite clays. As a result, films with improved self-cleaning functionality based on dust-repellency and omniphobic liquid-repellence (sheet resistance in the range of 107Ω/□ and contact angles of 106° (H2O) and 93° (oil)) were obtained. These unique films, being capable to repel dust and liquids, were applied to a variety of substrates (i.e., glass and plastics) and tested against solids and liquids of different nature with excellent performance. Bending tests of these holistic self-cleaning films deposited over flexible substrates showed better mechanical performance than unmodified laponite films.

Published
2024
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