1
|
Zhang H, Wang F, Ratke L, Nestler B. Brownian motion of droplets induced by thermal noise. Phys Rev E 2024; 109:024208. [PMID: 38491665 DOI: 10.1103/physreve.109.024208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 01/09/2024] [Indexed: 03/18/2024]
Abstract
Brownian motion (BM) is pivotal in natural science for the stochastic motion of microscopic droplets. In this study, we investigate BM driven by thermal composition noise at submicro scales, where intermolecular diffusion and surface tension both are significant. To address BM of microscopic droplets, we develop two stochastic multiphase-field models coupled with the full Navier-Stokes equation, namely, Allen-Cahn-Navier-Stokes and Cahn-Hilliard-Navier-Stokes. Both models are validated against capillary-wave theory; the Einstein's relation for the Brownian coefficient D^{*}∼k_{B}T/r at thermodynamic equilibrium is recovered. Moreover, by adjusting the co-action of the diffusion, Marangoni effect, and viscous friction, two nonequilibrium phenomena are observed. (I) The droplet motion transits from the Brownian to Ballistic with increasing Marangoni effect which is emanated from the energy dissipation mechanism distinct from the conventional fluctuation-dissipation theorem. (II) The deterministic droplet motion is triggered by the noise induced nonuniform velocity field which leads to a novel droplet coalescence mechanism associated with the thermal noise.
Collapse
Affiliation(s)
- Haodong Zhang
- Institute of Applied Materials-Microstructure Modelling and Simulation, Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Fei Wang
- Institute of Applied Materials-Microstructure Modelling and Simulation, Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Lorenz Ratke
- Institute of Materials Research, German Aerospace Center, Linder Hoehe, 51147 Cologne, Germany
| | - Britta Nestler
- Institute of Applied Materials-Microstructure Modelling and Simulation, Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany
- Institute of Digital Materials Science, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133 Karlsruhe, Germany
| |
Collapse
|
2
|
Fijalkowski M, Ali A, Qamer S, Coufal R, Adach K, Petrik S. Hybrid and Single-Component Flexible Aerogels for Biomedical Applications: A Review. Gels 2023; 10:4. [PMID: 38275842 PMCID: PMC10815221 DOI: 10.3390/gels10010004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 01/27/2024] Open
Abstract
The inherent disadvantages of traditional non-flexible aerogels, such as high fragility and moisture sensitivity, severely restrict their applications. To address these issues and make the aerogels efficient, especially for advanced medical applications, different techniques have been used to incorporate flexibility in aerogel materials. In recent years, a great boom in flexible aerogels has been observed, which has enabled them to be used in high-tech biomedical applications. The current study comprises a comprehensive review of the preparation techniques of pure polymeric-based hybrid and single-component aerogels and their use in biomedical applications. The biomedical applications of these hybrid aerogels will also be reviewed and discussed, where the flexible polymeric components in the aerogels provide the main contribution. The combination of highly controlled porosity, large internal surfaces, flexibility, and the ability to conform into 3D interconnected structures support versatile properties, which are required for numerous potential medical applications such as tissue engineering; drug delivery reservoir systems; biomedical implants like heart stents, pacemakers, and artificial heart valves; disease diagnosis; and the development of antibacterial materials. The present review also explores the different mechanical, chemical, and physical properties in numerical values, which are most wanted for the fabrication of different materials used in the biomedical fields.
Collapse
Affiliation(s)
- Mateusz Fijalkowski
- Department of Advanced Materials, Institute for Nanomaterials, Advanced Technologies and Innovation (CXI), Technical University of Liberec, 461 17 Liberec, Czech Republic
| | - Azam Ali
- Department of Material Science, Technical University of Liberec, 461 17 Liberec, Czech Republic
| | - Shafqat Qamer
- Department of Basic Medical Sciences, College of Medicine, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi Arabia
| | - Radek Coufal
- Department of Science and Research, Faulty of Health Studies, Technical University of Liberec, 461 17 Liberec, Czech Republic
| | - Kinga Adach
- Department of Advanced Materials, Institute for Nanomaterials, Advanced Technologies and Innovation (CXI), Technical University of Liberec, 461 17 Liberec, Czech Republic
| | - Stanislav Petrik
- Department of Advanced Materials, Institute for Nanomaterials, Advanced Technologies and Innovation (CXI), Technical University of Liberec, 461 17 Liberec, Czech Republic
| |
Collapse
|
3
|
Dayarian S, Majedi Far H, Yang L. Macroporous Polyimide Aerogels: A Comparison between Powder Microparticles Synthesized via Wet Gel Grinding and Emulsion Processes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:1804-1814. [PMID: 36706272 PMCID: PMC9910053 DOI: 10.1021/acs.langmuir.2c02696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 01/14/2023] [Indexed: 06/18/2023]
Abstract
It is noteworthy to mention that synthesizing the polyimide aerogel powder, which is carried out in this study, benefits from two advantages: (i) the powder particles can be used for some specific applications where the monolith is not suitable and (ii) there is a possibility to investigate how a polyimide aerogel monolith can be made through the polyimide powder to reduce its cost and cycle time. In this study, two straightforward methods, wet gel grinding and emulsion, are introduced to prepare polyimide aerogel powders using ambient pressure drying. The microscopic properties of interest, including skeletal and porous structures, microparticle size and assembly, combined with macroscopic properties such as thermal stabilities and conductivities (0.039 W/m·K), confirm that the fabricated microparticles with a size in the range of 7-20 μm and porosity in the range of 65-85% are thermally stable up to 500 °C.
Collapse
Affiliation(s)
- Shima Dayarian
- Department
of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, GlasgowG1 1XJ, United
Kingdom
| | - Hojat Majedi Far
- Blueshift
Materials Inc., Spencer, Massachusetts01562, United States
| | - Liu Yang
- Department
of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, GlasgowG1 1XJ, United
Kingdom
| |
Collapse
|
4
|
Ren J, Zhou J, Kong Y, Jiang X, Shen X. Development of Regular Hydrophobic Silica Aerogel Microspheres for Efficient Oil Adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:478-486. [PMID: 36573488 DOI: 10.1021/acs.langmuir.2c02732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The objective of this research was to develop new hydrophobic silica aerogel microspheres (HSAMs) with water glass and hexmethyldisilazane for oil adsorption. The effects of the hexmethyldisilazane concentration and drying method on the structure and organic liquid adsorption capacity were investigated. The hexmethyldisilazane concentration of the modification solution did not influence the microstructure and pore structure in a noteworthy manner, which depended more on the drying method. Vacuum drying led to more volume shrinkage of the silica gel microsphere (SGM) than supercritical CO2 drying, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution, and more compact network. Owing to the large pore volume and pore size, the HSAMs synthesized via supercritical CO2 drying had a larger organic liquid adsorption capacity. The adsorption capacities of the HSAMs with pore volumes of 4.04-6.44 cm3/g for colza oil, vacuum pump oil, and hexane are up to 18.3, 18.9, and 11.8 g/g, respectively, higher than for their state-of-the-art counterparts. The new sorbent preparation method is facile, cost-effective, safe, and ecofriendly, and the resulting HSAMs are exceptional in capacity, stability, and regenerability.
Collapse
Affiliation(s)
- Jian Ren
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
| | - Jiantao Zhou
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
| | - Yong Kong
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 210009, P. R. China
| | - Xing Jiang
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
| | - Xiaodong Shen
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 210009, P. R. China
| |
Collapse
|
5
|
Auto-Continuous Synthesis of Robust and Hydrophobic Silica Aerogel Microspheres from Low-Cost Aqueous Sodium Silicate for Fast Dynamic Organics Removal. Gels 2022; 8:gels8120778. [PMID: 36547303 PMCID: PMC9777793 DOI: 10.3390/gels8120778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/03/2022] Open
Abstract
An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica aerogel microsphere (RSAM) was prepared by polymer cross-linking on the framework of the silica gel. The pH value of the reaction system and the temperature of the coagulating bath were critical to form perfect SAMs with a diameter of 3.0 ± 0.2 mm. The grafted methyl groups are thermally stable up to 400 °C. Polymer cross-linking increased the strength significantly, owing to the polymer coating on the framework of silica aerogel. The pore volumes of HSAM (6.44 cm3/g) and RSAM (3.17 cm3/g) were much higher than their state-of-the-art counterparts. Their specific surface areas were also at a high level. The HSAM and RSAM showed high organic sorption capacities, i.e., 17.9 g/g of pump oil, 11.8 g/g of hexane, and 22.2 mg/g of 10 mg/L methyl orange. The novel preparation method was facile, cost-effective, safe, and eco-friendly, and the resulting SAM sorbents were exceptional in capacity, dynamics, regenerability, and stability.
Collapse
|
6
|
Vinayakumar K, Palliyarayil A, Kumar NS, Sil S. Processing of aerogels and their applications toward CO 2 adsorption and electrochemical reduction: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:47942-47968. [PMID: 35545748 DOI: 10.1007/s11356-022-20355-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/15/2022] [Indexed: 06/15/2023]
Abstract
Aerogels are a unique class of nanoporous ultralight materials exhibiting wide range of textural characteristic properties and tunable porosities. Due to their remarkable features such as low density, high surface area, low refractive index, small thermal conductivity, low dielectric constant and low sound velocity, they exhibit a wide range of applications in different areas such as electronics, thermal and acoustic insulation, chemistry, biomedicine and optics. The special advantages of these materials are that they can be produced in different forms such as monoliths/granular, bead/microspheres, thin films or sheets and as blankets. Aerogels are found to be potential materials for the removal of CO2 through adsorption or electrochemical reduction. There is a plethora of research on different kinds of aerogels used for CO2 adsorption process. Research has been going on toward the development of aerogel-based electrocatalyst, which can be used for valorization of CO2 through electrochemical reduction methods. Although most of the review papers have covered applications of aerogels in CO2 capture, very few discuss the processing of aerogels, more so on their applications in CO2 valorization. In this review, we have collated literature of different forms of aerogels currently available and the steps involved in their fabrication process. In addition, we have covered applications of aerogels in CO2 capture. Furthermore, we focussed on the basic principles involved in the development of an aerogel electrocatalyst as well as recent developments of aerogels in electrochemical CO2 reduction.
Collapse
Affiliation(s)
- Karthika Vinayakumar
- Department of Environmental Protection (DEP), Defence Bioengineering and Electromedical Laboratory (DEBEL), C V Raman Nagar, 560 093, Bangalore, India
| | - Ansari Palliyarayil
- Department of Environmental Protection (DEP), Defence Bioengineering and Electromedical Laboratory (DEBEL), C V Raman Nagar, 560 093, Bangalore, India
| | - Nallaperumal Shunmuga Kumar
- Department of Environmental Protection (DEP), Defence Bioengineering and Electromedical Laboratory (DEBEL), C V Raman Nagar, 560 093, Bangalore, India
| | - Sanchita Sil
- Department of Environmental Protection (DEP), Defence Bioengineering and Electromedical Laboratory (DEBEL), C V Raman Nagar, 560 093, Bangalore, India.
| |
Collapse
|
7
|
Zheng C, Yan C, Xie H, Huang L, Fu H, Zhang T, Huang Z. Preparation, properties, and degradation mechanism of thermosensitive self-degradation microgel. J DISPER SCI TECHNOL 2021. [DOI: 10.1080/01932691.2021.2010566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Cunchuan Zheng
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, The People’s Republic of China
| | - Chaozong Yan
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, The People’s Republic of China
| | - Hu Xie
- Xinjiang Oilfield Company’s first Gas Production, PetroChina Xinjiang Oilfield Company, Changji Hui Autonomous Prefecture, The People’s Republic of China
| | - Lamei Huang
- Research Institute of Exploration and Development, Tarim Oilfield Company, PetroChina, Tarim, The People’s Republic of China
| | - Haoran Fu
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, The People’s Republic of China
| | - Tailiang Zhang
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, The People’s Republic of China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Chengdu, The People’s Republic of China
| | - Zhiyu Huang
- School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, The People’s Republic of China
- Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Chengdu, The People’s Republic of China
| |
Collapse
|
8
|
Lebedev A, Lovskaya D, Menshutina N. Modeling and scale-up of supercritical fluid processes. Part II: Supercritical drying of gel particles. J Supercrit Fluids 2021. [DOI: 10.1016/j.supflu.2021.105238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
9
|
Effect of Process Conditions on the Properties of Resorcinol-Formaldehyde Aerogel Microparticles Produced via Emulsion-Gelation Method. Polymers (Basel) 2021; 13:polym13152409. [PMID: 34372011 PMCID: PMC8348565 DOI: 10.3390/polym13152409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/06/2021] [Accepted: 07/16/2021] [Indexed: 11/30/2022] Open
Abstract
Organic aerogels in the form of powder, microgranules and microsized particles receive considerable attention due to their easy fabrication, low process time and costs compared to their monolithic form. Here, we developed resorcinol-formaldehyde (RF) aerogel microparticles by using an emulsion-gelation method. The main objective of this study is to investigate the influence of curing time, stirring rate, RF sol:oil ratio and initial pH of the sol in order to control the size and properties of the microparticles produced. The emulsion-gelation of RF sol prepared with sodium carbonate catalyst in an oil phase at 60 °C was explored. RF microparticles were washed with ethanol to remove the oil phase followed by supercritical and ambient pressure drying. The properties of the dried RF microparticles were analyzed using FT-IR, N2 adsorption isotherm, gas pycnometry, wide angle X-ray scattering and scanning electron microscope. RF microparticles with high surface area up to 543 m2/g and large pore volume of 1.75 cm3/g with particle sizes ranging from 50–425 µm were obtained.
Collapse
|
10
|
Athamneh T, Amin A, Benke E, Ambrus R, Gurikov P, Smirnova I, Leopold CS. Pulmonary drug delivery with aerogels: engineering of alginate and alginate-hyaluronic acid microspheres. Pharm Dev Technol 2021; 26:509-521. [PMID: 33593203 DOI: 10.1080/10837450.2021.1888979] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In this study, the aerogel technology was used to prepare pulmonary drug carriers consisting of alginate and alginate-hyaluronic acid by an emulsion gelation technique and supercritical CO2 drying. During the preparation process, the emulsification rate and inner phase viscosity were varied to control the diameter of aerogel microspheres. Results showed that the aerogel microspheres were highly porous (porosity > 98%) with low densities in the range between 0.0087 and 0.0634 g/cm3 as well as high surface areas between 354 and 759 m2/g. The obtained microspheres showed aerodynamic diameter below 5 µm making them suitable for pulmonary drug delivery. An in vitro drug release study with the model drug sodium naproxen was conducted and a non-Fickian drug release mechanism was observed, with no significant difference between the release profiles of alginate and alginate-hyaluronic acid microspheres. During the emulsion gelation step, the feasibility of using the capillary number to estimate the largest stable droplet size in the emulsions was also studied and it was found that using this number, the droplet size in the emulsions may well be predicted.
Collapse
Affiliation(s)
- Tamara Athamneh
- Institute of Thermal Separation Processes, Hamburg University of Technology, Hamburg, Germany.,Institute of Pharmacy, Division of Pharmaceutical Technology, University of Hamburg, Hamburg, Germany
| | - Adil Amin
- Institute of Thermal Separation Processes, Hamburg University of Technology, Hamburg, Germany
| | - Edit Benke
- Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, Szeged, Hungary
| | - Rita Ambrus
- Institute of Pharmaceutical Technology and Regulatory Affairs, University of Szeged, Szeged, Hungary
| | - Pavel Gurikov
- Laboratory for Development and Modelling of Novel Nanoporous Materials, Hamburg, Germany
| | - Irina Smirnova
- Institute of Thermal Separation Processes, Hamburg University of Technology, Hamburg, Germany
| | - Claudia S Leopold
- Institute of Pharmacy, Division of Pharmaceutical Technology, University of Hamburg, Hamburg, Germany
| |
Collapse
|
11
|
García-González CA, Sosnik A, Kalmár J, De Marco I, Erkey C, Concheiro A, Alvarez-Lorenzo C. Aerogels in drug delivery: From design to application. J Control Release 2021; 332:40-63. [PMID: 33600880 DOI: 10.1016/j.jconrel.2021.02.012] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/05/2021] [Accepted: 02/06/2021] [Indexed: 12/28/2022]
Abstract
Aerogels are the lightest processed solid materials on Earth and with the largest empty volume fraction in their structure. Composition versatility, modularity, and feasibility of industrial scale manufacturing are behind the fast emergence of aerogels in the drug delivery field. Compared to other 3D materials, the high porosity (interconnected mesopores) and high specific surface area of aerogels may allow faster loading of small-molecule drugs, less constrained access to inner regions of the matrix, and more efficient interactions of the biological milieu with the polymer matrix. Processing in supercritical CO2 medium for both aerogel production (drying) and drug loading (impregnation) has remarkable advantages such as absence of an oxidizing environment, clean manufacture, and easiness for the scale-up under good manufacturing practices. The aerogel solid skeleton dictates the chemical affinity to the different drugs, which in turn determines the loading efficiency and the release pattern. Aerogels can be used to increase the solubility of BCS Class II and IV drugs because the drug can be deposited in amorphous state onto the large surface area of the skeleton, which facilitates a rapid contact with the body fluids, dissolution, and release. Conversely, tuning the aerogel structure by functionalization with drug-binding moieties or stimuli-responsive components, application of coatings and incorporation of drug-loaded aerogels into other matrices may enable site-specific, stimuli-responsive, or prolonged drug release. The present review deals with last decade advances in aerogels for drug delivery. An special focus is paid first on the loading efficiency of active ingredients and release kinetics under biorelevant conditions. Subsequent sections deal with aerogels intended to address specific therapeutic demands. In addition to oral delivery, the physical properties of the aerogels appear to be very advantageous for mucosal administration routes, such as pulmonary, nasal, or transdermal. A specific section devoted to recent achievements in gene therapy and theranostics is also included. In the last section, scale up strategies and life cycle assessment are comprehensively addressed.
Collapse
Affiliation(s)
- Carlos A García-González
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I+D Farma (GI-1645), Facultad de Farmacia and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Alejandro Sosnik
- Laboratory of Pharmaceutical Nanomaterials Science, Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - József Kalmár
- Department of Inorganic and Analytical Chemistry, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary
| | - Iolanda De Marco
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, SA, Italy
| | - Can Erkey
- Chemical and Biological Engineering Department, Koç University, 34450 Sarıyer, Istanbul, Turkey
| | - Angel Concheiro
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I+D Farma (GI-1645), Facultad de Farmacia and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Carmen Alvarez-Lorenzo
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I+D Farma (GI-1645), Facultad de Farmacia and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| |
Collapse
|
12
|
Shi W, Ching YC, Chuah CH. Preparation of aerogel beads and microspheres based on chitosan and cellulose for drug delivery: A review. Int J Biol Macromol 2021; 170:751-767. [PMID: 33412201 DOI: 10.1016/j.ijbiomac.2020.12.214] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/24/2020] [Accepted: 12/29/2020] [Indexed: 12/11/2022]
Abstract
Spherical aerogels are not easily broken during use and are easier to transport and store which can be used as templates for drug delivery. This review summarizes the possible approaches for the preparation of aerogel beads and microspheres based on chitosan and cellulose, an overview to the methods of manufacturing droplets is presented, afterwards, the transition mechanisms from sol to a spherical gel are reviewed in detail followed by different drying processes to obtain spherical aerogels with porous structures. Additionally, a specific focus is given to aerogel beads and microspheres to be regarded as drug delivery carriers. Furthermore, a core/shell architecture of aerogel beads and microspheres for controlled drug release is described and subjected to inspire readers to create novel drug release system. Finally, the conclusions and outlooks of aerogel beads and microspheres for drug delivery are summarized.
Collapse
Affiliation(s)
- Wei Shi
- Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Yern Chee Ching
- Department of Chemical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia.
| | - Cheng Hock Chuah
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia
| |
Collapse
|
13
|
Budtova T, Aguilera DA, Beluns S, Berglund L, Chartier C, Espinosa E, Gaidukovs S, Klimek-Kopyra A, Kmita A, Lachowicz D, Liebner F, Platnieks O, Rodríguez A, Tinoco Navarro LK, Zou F, Buwalda SJ. Biorefinery Approach for Aerogels. Polymers (Basel) 2020; 12:E2779. [PMID: 33255498 PMCID: PMC7760295 DOI: 10.3390/polym12122779] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/20/2020] [Accepted: 11/21/2020] [Indexed: 12/30/2022] Open
Abstract
According to the International Energy Agency, biorefinery is "the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)". In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels' environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action "CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences".
Collapse
Affiliation(s)
- Tatiana Budtova
- MINES ParisTech, Center for Materials Forming (CEMEF), PSL Research University, UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France; (D.A.A.); (C.C.); (F.Z.)
| | - Daniel Antonio Aguilera
- MINES ParisTech, Center for Materials Forming (CEMEF), PSL Research University, UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France; (D.A.A.); (C.C.); (F.Z.)
| | - Sergejs Beluns
- Faculty of Materials Science and Applied Chemistry, Institute of Polymer Materials, Riga Technical University, P.Valdena 3/7, LV, 1048 Riga, Latvia; (S.B.); (S.G.); (O.P.)
| | - Linn Berglund
- Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden;
| | - Coraline Chartier
- MINES ParisTech, Center for Materials Forming (CEMEF), PSL Research University, UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France; (D.A.A.); (C.C.); (F.Z.)
| | - Eduardo Espinosa
- Bioagres Group, Chemical Engineering Department, Faculty of Science, Universidad de Córdoba, Campus of Rabanales, 14014 Córdoba, Spain; (E.E.); (A.R.)
| | - Sergejs Gaidukovs
- Faculty of Materials Science and Applied Chemistry, Institute of Polymer Materials, Riga Technical University, P.Valdena 3/7, LV, 1048 Riga, Latvia; (S.B.); (S.G.); (O.P.)
| | - Agnieszka Klimek-Kopyra
- Department of Agroecology and Plant Production, Faculty of Agriculture and Economics, University of Agriculture, Aleja Mickieiwcza 21, 31-120 Kraków, Poland;
| | - Angelika Kmita
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland; (A.K.); (D.L.)
| | - Dorota Lachowicz
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland; (A.K.); (D.L.)
| | - Falk Liebner
- Department of Chemistry, Institute for Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Straße 24, A-3430 Tulln an der Donau, Austria;
| | - Oskars Platnieks
- Faculty of Materials Science and Applied Chemistry, Institute of Polymer Materials, Riga Technical University, P.Valdena 3/7, LV, 1048 Riga, Latvia; (S.B.); (S.G.); (O.P.)
| | - Alejandro Rodríguez
- Bioagres Group, Chemical Engineering Department, Faculty of Science, Universidad de Córdoba, Campus of Rabanales, 14014 Córdoba, Spain; (E.E.); (A.R.)
| | - Lizeth Katherine Tinoco Navarro
- CEITEC-VUT Central European Institute of Technology—Brno university of Technology, Purkyňova 123, 612 00 Brno-Královo Pole, Czech Republic;
| | - Fangxin Zou
- MINES ParisTech, Center for Materials Forming (CEMEF), PSL Research University, UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France; (D.A.A.); (C.C.); (F.Z.)
| | - Sytze J. Buwalda
- MINES ParisTech, Center for Materials Forming (CEMEF), PSL Research University, UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France; (D.A.A.); (C.C.); (F.Z.)
| |
Collapse
|
14
|
Lu J, Li Y, Song W, Losego MD, Monikandan R, Jacob KI, Xiao R. Atomic Layer Deposition onto Thermoplastic Polymeric Nanofibrous Aerogel Templates for Tailored Surface Properties. ACS NANO 2020; 14:7999-8011. [PMID: 32644796 DOI: 10.1021/acsnano.9b09497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous aerogel (NFA) templates were fabricated through vacuum freeze-drying from EVOH nanofibrous suspensions. Aluminum oxide (Al2O3) layers were deposited onto highly porous templates to form organic-inorganic hybrid aerogels by the atomic layer deposition (ALD) technique. Chemical and physical measurements showed that mechanical properties were improved through ALD. In addition, the surface chemistry of ALD modified aerogels showed a fascinating cyclic change based on the number of ALD deposition cycles. A transition from hydrophilicity to hydrophobicity was observed after a few cycles of ALD coating; however, additional deposition cycles changed the wettability characteristics back to hydrophilicity. This hydrophilic-hydrophobic-hydrophilic variation is shown to be governed by a combination of geometrical and chemical surface properties. Furthermore, the deposited Al2O3 could substantially improve aerogels strength and reduce permanent deformation after cyclic compression. The Young's modulus of aerogels increased from 5.54 to 33.27 kPa, and the maximum stress at 80% strain went up from 31.13 to 176.11 kPa, after 100 cycles of trimethyl-aluminum (TMA)/water ALD. Thermogravimetric analysis (TGA) results confirm that ALD can effectively improve the heat resistance characteristics of polymeric aerogel. The onset temperature and the residual mass increased with increasing numbers of ALD cycles. During pyrolysis, the nanofiber cores were decomposed, and the brittle pure Al2O3 self-supporting nanotube aerogels with the continuous hollow nanotubular network were formed. A coating of continuous thickness Al2O3 layer on individual nanofiber was achieved after 100 ALD cycles. In additional to mechanical strength and physical property changes, the ALD modified aerogel also shows a superhydrophobic and oleophilic surface chemistry, which could potentially be used to remove oils/organic solvents from water. The resultant aerogels exhibit excellent absorption capacity (31-73 g/g) for various liquids, and the material could be reused after distillation or squeezing. A successful scale-up of such materials could provide some insights into the design and development of thermoplastic polymeric NFAs with substantial industrial applications.
Collapse
Affiliation(s)
- Jianwei Lu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- The Georgia W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Yi Li
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Renewable Bioproducts Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Wei Song
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| | - Mark D Losego
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Renewable Bioproducts Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Rebhadevi Monikandan
- Materials Characterization Facility, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Karl I Jacob
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- The Georgia W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- Renewable Bioproducts Institute, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Ru Xiao
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China
| |
Collapse
|
15
|
Alsmadi MM, Obaidat RM, Alnaief M, Albiss BA, Hailat N. Development, In Vitro Characterization, and In Vivo Toxicity Evaluation of Chitosan-Alginate Nanoporous Carriers Loaded with Cisplatin for Lung Cancer Treatment. AAPS PharmSciTech 2020; 21:191. [PMID: 32661587 DOI: 10.1208/s12249-020-01735-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/16/2020] [Indexed: 12/12/2022] Open
Abstract
Polysaccharide-based aerogels are promising drug carriers. Being nanoporous with a high specific surface area allows their use as a drug vehicle for various delivery routes. Intratracheal and intravenous administration of free cisplatin causes toxicity in the rat liver, lungs, and kidneys. In this work, microspherical particles based on alginate-chitosan without a traditional crosslinker were evaluated for targeted delivery of cisplatin by intratracheal administration. The aerogel particles were prepared using the emulsion gelation method, followed by supercritical carbon dioxide extraction. Loading of cisplatin on the prepared porous particles was performed by impregnation using supercritical fluid technology. The prepared carrier and the loaded drug were evaluated for drug content, release, and in vivo acute and subacute toxicity. Cisplatin was successfully loaded (percent drug loading > 76%) on the prepared carrier (particle size = 0.433 ± 0.091 μm) without chemically interacting with the carrier and without losing its crystal form. Sixty percent of cisplatin was released within 2 h, and the rest was loaded inside the polymer pores and had a sustained first-order release over 6 h. Loading cisplatin on the carrier developed herein reduced the cisplatin lung toxicity but increased the liver toxicity after intratracheal administration with nephrotoxicity being proportional to cisplatin dose in case of carrier-loaded cisplatin. Moreover, loading cisplatin on the carrier significantly reduced mortality rate and prevented weight loss in rats as compared to free cisplatin in subacute studies after intratracheal administration. Thus, the developed carrier showed high potential for targeted delivery of cisplatin for lung cancer treatment by inhalation. Graphical abstract.
Collapse
|
16
|
Impregnation of passion fruit bagasse extract in alginate aerogel microparticles. Int J Biol Macromol 2020; 155:1060-1068. [DOI: 10.1016/j.ijbiomac.2019.11.070] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 10/24/2019] [Accepted: 11/07/2019] [Indexed: 11/22/2022]
|
17
|
New Trends in Bio-Based Aerogels. Pharmaceutics 2020; 12:pharmaceutics12050449. [PMID: 32414217 PMCID: PMC7284463 DOI: 10.3390/pharmaceutics12050449] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/27/2020] [Accepted: 05/11/2020] [Indexed: 01/16/2023] Open
Abstract
(1) Background: The fascinating properties of currently synthesized aerogels associated with the flexible approach of sol-gel chemistry play an important role in the emergence of special biomedical applications. Although it is increasingly known and mentioned, the potential of aerogels in the medical field is not sufficiently explored. Interest in aerogels has increased greatly in recent decades due to their special properties, such as high surface area, excellent thermal and acoustic properties, low density and thermal conductivity, high porosity, flame resistance and humidity, and low refractive index and dielectric constant. On the other hand, high manufacturing costs and poor mechanical strength limit the growth of the market. (2) Results: In this paper, we analyze more than 180 articles from recent literature studies focused on the dynamics of aerogels research to summarize the technologies used in manufacturing and the properties of materials based on natural polymers from renewable sources. Biomedical applications of these bio-based materials are also introduced. (3) Conclusions: Due to their complementary functionalities (bioactivity, biocompatibility, biodegradability, and unique chemistry), bio-based materials provide a vast capability for utilization in the field of interdisciplinary and multidisciplinary scientific research.
Collapse
|
18
|
Abstract
AbstractPea and amylomaize starches were used to produce aerogel in form of monoliths and microparticles. The formation of starch gel was investigated, and we showed that each starch needed a different pasting temperature for its complete dissolution. The gelation kinetics was investigated with oscillatory rheometry for both systems as a function of the starch concentration. The gelation and retrogradation temperature of the starch gel were varied and its impact on the final aerogel evaluated. The emulsion gelation was carried out batch wise in a stirred vessel with different impeller geometries, concentrations of surfactant (Span80 and PGPR) and stirring rates. A particle size prediction approach based on idealized flow (Couette, 2D hyperbolic and turbulent) during the emulsification was proposed. A semi-continuous set-up for the emulsion gelation was developed in which the emulsification occurs in a single pass through a colloid mill and the gelation is triggered in-line with a counter-current heat exchanger.
Collapse
|
19
|
Druel L, Kenkel A, Baudron V, Buwalda S, Budtova T. Cellulose Aerogel Microparticles via Emulsion-Coagulation Technique. Biomacromolecules 2020; 21:1824-1831. [PMID: 32011867 DOI: 10.1021/acs.biomac.9b01725] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cellulose aerogel microparticles were made via emulsification/nonsolvent induced phase separation/drying with supercritical CO2. Cellulose was dissolved in NaOH-based solvent with and without additives in order to control solution gelation. Two emulsions, cellulose solution/oil and cellulose nonsolvent/oil, were mixed to start nonsolvent induced phase separation (or coagulation) of cellulose inside each cellulose droplet leading to the formation of so-called microgels. Different options of triggering coagulation were tested, by coalescence of droplets of cellulose solution and cellulose nonsolvent and by diffusion of nonsolvent partly soluble in the oil, accompanied by coalescence. The second option was found to be the most efficient for stabilization of the shape of coagulated cellulose microgels. The influence of gelation on particle formation and aerogel properties was investigated. The aerogel particles' diameter was around a few tens of microns, and the specific surface area was 250-350 m2/g.
Collapse
Affiliation(s)
- Lucile Druel
- MINES ParisTech, PSL Research University, Center for Materials Forming (CEMEF), UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France
| | - Amelie Kenkel
- MINES ParisTech, PSL Research University, Center for Materials Forming (CEMEF), UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France.,Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany
| | - Victor Baudron
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073 Hamburg, Germany
| | - Sytze Buwalda
- MINES ParisTech, PSL Research University, Center for Materials Forming (CEMEF), UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France
| | - Tatiana Budtova
- MINES ParisTech, PSL Research University, Center for Materials Forming (CEMEF), UMR CNRS 7635, CS 10207, 06904 Sophia Antipolis, France
| |
Collapse
|
20
|
Jiang X, Kong Y, Zhao Z, Shen X. Spherical amine grafted silica aerogels for CO2 capture. RSC Adv 2020; 10:25911-25917. [PMID: 35518618 PMCID: PMC9055311 DOI: 10.1039/d0ra04497k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 06/29/2020] [Indexed: 12/23/2022] Open
Abstract
The objective of this research was to develop a novel spherical amine grafted silica aerogel for CO2 capture. A spherical silica gel was synthesized by dropping a sodium silicate based silica sol into an oil bath. Amine grafting was achieved by bonding 3-aminopropyltriethoxysilane onto the framework of the silica gel. The spherical amine grafted silica gels were dried using vacuum drying to prepare the spherical amine grafted silica aerogels (SASAs). The synthetic mechanism of the SASAs was proposed. The structures and the CO2 adsorption performances of SASAs were researched. The amine loading of the SASAs increased with the grafting time, however, the specific surface area and pore volume sharply decreased owing to the blockage of the pore space. Excess amine loading led to the decrease of the CO2 adsorption capacity. The optimal CO2 adsorption capacity was 1.56 mmol g−1 with dry 1% CO2 and at 35 °C. This work provides a low-cost and environmentally friendly way to design a capable and regenerable adsorbent material. The objective of this research was to develop a novel spherical amine grafted silica aerogel for CO2 capture.![]()
Collapse
Affiliation(s)
- Xing Jiang
- College of Materials Science and Engineering
- Nanjing Tech University
- Nanjing 210009
- P. R. China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites
| | - Yong Kong
- College of Materials Science and Engineering
- Nanjing Tech University
- Nanjing 210009
- P. R. China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites
| | - Zhiyang Zhao
- College of Materials Science and Engineering
- Nanjing Tech University
- Nanjing 210009
- P. R. China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites
| | - Xiaodong Shen
- College of Materials Science and Engineering
- Nanjing Tech University
- Nanjing 210009
- P. R. China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites
| |
Collapse
|
21
|
Paraskevopoulou P, Smirnova I, Athamneh T, Papastergiou M, Chriti D, Mali G, Čendak T, Raptopoulos G, Gurikov P. Polyurea-crosslinked biopolymer aerogel beads. RSC Adv 2020. [DOI: 10.1039/d0ra07337g] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Polyurea-crosslinked calcium alginate and chitosan aerogel beads: novel fibrous biopolymer-based aerogels.
Collapse
Affiliation(s)
- Patrina Paraskevopoulou
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Irina Smirnova
- Institute of Thermal Separation Processes
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
| | - Tamara Athamneh
- Institute of Thermal Separation Processes
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
| | - Maria Papastergiou
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Despoina Chriti
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Gregor Mali
- National Institute of Chemistry
- 1000 Ljubljana
- Slovenia
| | - Tomaž Čendak
- National Institute of Chemistry
- 1000 Ljubljana
- Slovenia
| | - Grigorios Raptopoulos
- Inorganic Chemistry Laboratory
- Department of Chemistry
- National and Kapodistrian University of Athens
- Athens
- Greece
| | - Pavel Gurikov
- Laboratory for Development and Modelling of Novel Nanoporous Materials
- Hamburg University of Technology
- 21073 Hamburg
- Germany,
| |
Collapse
|
22
|
Athamneh T, Amin A, Benke E, Ambrus R, Leopold CS, Gurikov P, Smirnova I. Alginate and hybrid alginate-hyaluronic acid aerogel microspheres as potential carrier for pulmonary drug delivery. J Supercrit Fluids 2019. [DOI: 10.1016/j.supflu.2019.04.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
23
|
Synthetic Polymer Aerogels in Particulate Form. MATERIALS 2019; 12:ma12091543. [PMID: 31083421 PMCID: PMC6539448 DOI: 10.3390/ma12091543] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/22/2019] [Accepted: 05/06/2019] [Indexed: 11/17/2022]
Abstract
Aerogels have been defined as solid colloidal or polymeric networks of nanoparticles that are expanded throughout their entire volume by a gas. They have high surface areas, low thermal conductivities, low dielectric constants, and high acoustic attenuation, all of which are very attractive properties for applications that range from thermal and acoustic insulation to dielectrics to drug delivery. However, one of the most important impediments to that potential has been that most efforts have been concentrated on monolithic aerogels, which are prone to defects and their production requires long and costly processing. An alternative approach is to consider manufacturing aerogels in particulate form. Recognizing that need, the European Commission funded “NanoHybrids”, a 3.5 years project under the Horizon 2020 framework with 12 industrial and academic partners aiming at aerogel particles from bio- and synthetic polymers. Biopolymer aerogels in particulate form have been reviewed recently. This mini-review focuses on the emerging field of particulate aerogels from synthetic polymers. That category includes mostly polyurea aerogels, but also some isolated cases of polyimide and phenolic resin aerogels. Particulate aerogels covered include powders, micro granules and spherical millimeter-size beads. For the benefit of the reader, in addition to the literature, some new results from our laboratory concerning polyurea particle aerogels are also included.
Collapse
|