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Functional 3D Porous Nanostructured Materials-Aerogels

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Materials Science and Engineering".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 11575

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Special Issue Editor

Dr. Hajar Maleki

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Institute of Inorganic Chemistry, Department of Chemistry, University of Cologne, Greinstraße 6, 50939 Köln
Interests: sol–gel-based porous (hybrid) materials, development of functional materials, mechanically flexible foam-based pressure sensors (piezoresistive and piezoelectric), development of nanoparticles
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Special Issue Information

Dear Colleagues,

Aerogels were discovered for the first time by Kistler in 1930, and are a striking example of materials with a fascinating combination of properties such as high porosity (90%–99%) comprising micro- and mesoporosity (2 nm < pore diameter (φ) < 50 nm), low densities (0.001–0.2 g cm⁻³), and high specific surface areas (500–1500 m² g⁻¹), sometimes together with transparency. They are typically prepared by sol–gel processes accompanied by an appropriate drying technique (usually supercritical drying), rendering them as appropriate candidates for a multitude of applications such as for thermal insulation, as catalysts and catalyst supports, as pollutant sorbents for environmental cleaning, or in biomedical and pharmaceutical applications. Apart from nanostructuration of various organic, inorganic, and hybrid molecular building blocks, aerogels can also be developed through the assembly of nanoscale zero-, one-, and two-dimensional (0D,1D, and 2D) nanomaterials.

In this Special Issue, we are interested in original research papers, communications, and review papers addressing the current challenges of aerogel development for the abovementioned applications. This includes:

Introduction of new synthesis approaches for new emerging aerogel-based materials;
Studies of microstructural, mechanical, and other physical properties;
Advanced aerogel fabrication techniques, e.g., additive manufacturing;
Cost- and time-efficient synthesis and processing of aerogels;
Simulations, including multiscale modeling of aerogel properties.

Dr. Hajar Maleki
Guest Editor

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Keywords

aerogel
3D nanostructured materials
porous
sol–gel
supercritical drying
mechanical properties
aerogel simulation

Published Papers (3 papers)

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Research

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16 pages, 24817 KiB

Open AccessArticle

Effect of Cellulose Characteristics on the Properties of the Wet-Spun Aerogel Fibers

by Matin Rostamitabar, Gunnar Seide, Stefan Jockenhoevel and Samaneh Ghazanfari

Appl. Sci. 2021, 11(4), 1525; https://0-doi-org.brum.beds.ac.uk/10.3390/app11041525 - 08 Feb 2021

Cited by 13 | Viewed by 4146

Abstract

Cellulose aerogels (CAs) from plant or bacterial-derived cellulose have advantages such as low density, high porosity, and high specific surface area and have been used in various applications including biomedical fields. One limiting factor in developing CAs is their demanding shaping process since it involves several steps of dissolution/dispersion of cellulose, geometry configurations using molds or nozzles, coagulation and washing of the gel body, and drying techniques. CA fibers can be converted into textiles and enhance the design ability, stiffness, and flexibility of the CAs. This study aims to understand the correlations between the initial cellulose characteristics, aerogel’s internal structure, and its prospective biomedical application. Wet-spun CA fibers were obtained by supercritical CO₂ drying from low and high molecular weight microcrystalline cellulose in calcium thiocyanate tetrahydrate solution. Fiber spinning, thermal behavior, textural properties, and biological assessments of the CA fibers were inspected. The CA microfibers from high molecular weight cellulose proved to have a higher surface area (~197 m²/g), denser structure, and finer nanofibrils (~2 nm) with better thermal stability in comparison with the fibers produced from low molecular weight cellulose. The fibers were nontoxic, and cell proliferation was observed over time. CA fibers showed promising results to be used for biomedical applications such as tissue engineering and wound care. Full article

(This article belongs to the Special Issue Functional 3D Porous Nanostructured Materials-Aerogels)

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16 pages, 4684 KiB

Open AccessFeature PaperArticle

Facile Preparation of Biocompatible and Transparent Silica Aerogels as Ionogels Using Choline Dihydrogen Phosphate Ionic Liquid

by Seeni Meera Kamal Mohamed, Rajavelu Murali Sankar, Manikantan Syamala Kiran, Sellamuthu N. Jaisankar, Barbara Milow and Asit Baran Mandal

Appl. Sci. 2021, 11(1), 206; https://0-doi-org.brum.beds.ac.uk/10.3390/app11010206 - 28 Dec 2020

Cited by 4 | Viewed by 2502

Abstract

We developed a facile and greener approach for the preparation of silica-aerogel-based ionogels using choline dihydrogen phosphate ionic liquid by the sol–gel approach. A series of silica-based aerogels as ionogels were prepared by varying the ionic liquid concentrations: 0.1, 0.5, 1, 3, 5, and 10 wt %. The as-prepared ionogels were characterized using several analytical techniques, namely, attenuated total reflectance (ATR)/FT-IR, TGA, XRD, and particle size analyses. The role of ionic liquid in the viscoelastic properties of the sol–gel transition was monitored using time-dependent rheological measurements. The addition of ionic liquid to the sol–gel system favored the formation of a more interconnected silica network structure. The formation of a silica network structure during sol–gel hydrolysis and condensation was confirmed from ²⁹Si solid-state CP/MAS NMR spectra. The effect of the ionic liquid on the morphological properties was investigated using SEM and TEM studies. The cell viabilities of the prepared gel samples were clearly evident from the cytotoxicity assay studies using Swiss and HaCaT cells. The main advantages of using biocompatible ionic liquids for the preparation of these aerogels as ionogels are that they may be used for encapsulating biological molecules and retain their conformational stability for a longer duration. Full article

(This article belongs to the Special Issue Functional 3D Porous Nanostructured Materials-Aerogels)

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Review

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36 pages, 6599 KiB

Open AccessReview

Silica Mesoporous Structures: Effective Nanocarriers in Drug Delivery and Nanocatalysts

by Masoud Mirzaei, Malihe Babaei Zarch, Mahdieh Darroudi, Khalilollah Sayyadi, Seyed Tahmoures Keshavarz, Jalil Sayyadi, Azadeh Fallah and Hajar Maleki

Appl. Sci. 2020, 10(21), 7533; https://0-doi-org.brum.beds.ac.uk/10.3390/app10217533 - 26 Oct 2020

Cited by 29 | Viewed by 4275

Abstract

The application of silica mesoporous structures in drug delivery and the removal of pollutants and organic compounds through catalytic reactions is increasing due to their unique characteristics, including high loading capacities, tunable pores, large surface areas, sustainability, and so on. This review focuses on very well-studied class of different construction mesoporous silica nano(particles), such as MCM-41, SBA-15, and SBA-16. We discuss the essential parameters involved in the synthesis of these materials with providing a diverse set of examples. In addition, the recent advances in silica mesoporous structures for drug delivery and catalytic applications are presented to fill the existing gap in the literature with providing some promising examples on this topic for the scientists in both industry and academia active in the field. Regarding the catalytic applications, mesoporous silica particles have shown some promises to remove the organic pollutants and to synthesize final products with high yields due to the ease with which their surfaces can be modified with various ligands to create appropriate interactions with target molecules. In the drug delivery process, as nanocarriers, they have also shown very good performance thanks to the easy surface functionalization but also adjustability of their porosities to providing in-vivo and in-vitro cargo delivery at the target site with appropriate rate. Full article

(This article belongs to the Special Issue Functional 3D Porous Nanostructured Materials-Aerogels)

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