As part of the Materials International Space Station Experiment (MISSE) missions, polyimide aerogel samples as prepared and atomic oxygen plasma treated with bulk densities of 0.09 and 0.15 g/cm3 were exposed on the exterior of the International Space Station (ISS) during MISSE-9, 12, and 15 missions for 0.77, 0.89, and 0.44year direct space exposure times, respectively. The aerogel samples were synthesized from a combination of the diamines 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane (BAPN) and 2,2 '-dimethylbenzidine (DMBZ), 3,3 ',4,4 '-biphenyltetracarboxylic dianhydride (BPDA), and 1,3,5-triaminophenoxybenzene (TAB) as the crosslinker. At low Earth orbit (LEO), spacecraft are subjected to extreme environmental conditions such as thermal cycling, solar radiation, cosmic rays, solar wind charged particles and atomic oxygen (AO). A post-flight analysis of aerogel physical, chemical, mechanical, thermal and optical properties were performed using a series of nondestructive techniques. The polyimide aerogels exhibited a notably higher AO erosion yield compared to nonporous Kapton H or HN polyimides, attributed to their order of magnitude lower bulk density and much higher surface area. Yet, the post-flight characterizations reveal no significant degradation in material properties. For example, in terms of material's structural integrity, the post-flight Young's moduli at both low and high densities were not statistically changed. Similar observations were obtained for thermal and optical properties in terms of changes in the materials' thermal conductivity and solar absorptance. The aerogel flight samples with pre-flight surface treatments using atomic oxygen plasma showed a higher susceptibility to the LEO environment compared to as-prepared aerogel flight samples. Despite their high AO erosion yield, this study shows that polyimide aerogels maintain remarkable stability throughout extended space missions and explorations and therefore can be considered as a space-rated material.

ADVERTISEMENT RETURN TO ARTICLES ASAPEditorialNEXTACS Materials Au: Announcing the 2023 Rising Stars in Materials ScienceStephanie L. Brock*Stephanie L. Brock*Email: [email protected]More by Stephanie L. Brockhttps://orcid.org/0000-0002-0439-302X, Maksym V. KovalenkoMaksym V. KovalenkoMore by Maksym V. Kovalenkohttps://orcid.org/0000-0002-6396-8938, and Mary Ann MeadorMary Ann MeadorMore by Mary Ann MeadorCite this: ACS Mater. Au 2024, XXXX, XXX, XXX-XXXPublication Date (Web):February 8, 2024Publication History Received29 January 2024Published online8 February 2024https://doi.org/10.1021/acsmaterialsau.4c00004© 2024 American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0. License Summary*You are free to share (copy and redistribute) this article in any medium or format within the parameters below:Creative Commons (CC): This is a Creative Commons license.Attribution (BY): Credit must be given to the creator.Non-Commercial (NC): Only non-commercial uses of the work are permitted. No Derivatives (ND): Derivative works may be created for non-commercial purposes, but sharing is prohibited. View full license*DisclaimerThis summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials. This publication is Open Access under the license indicated. Learn MoreArticle Views-Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (12 MB) Get e-AlertscloseSUBJECTS:Biomaterials,Energy,Materials,Materials science,Sensors Get e-Alerts

As a class of materials, polymer aerogels have many of the same properties as silica aerogels, including high surface area, low density, low dielectric constants, and low thermal conductivity. However, many polymer aerogels also possess mechanical properties far exceeding those of silica aerogels, making them much more applicable as low dielectric substrates, durable insulation, or lightweight multifunctional structures. The use of engineering polymers, such as polyimide and polyamide, as the aerogel backbone, adds the potential for higher use temperatures, combined with good mechanical properties. In addition, by tuning the backbone chemistry, polyimide and polyamide aerogels provide an endless ability to dial in properties for specific aerospace and other applications.

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTACS Materials Au: Announcing the 2022 Rising Stars in Materials ScienceStephanie L. Brock*Stephanie L. Brock*Email: [email protected]More by Stephanie L. Brockhttps://orcid.org/0000-0002-0439-302X, Maksym V. KovalenkoMaksym V. KovalenkoMore by Maksym V. Kovalenkohttps://orcid.org/0000-0002-6396-8938, and Mary Ann MeadorMary Ann MeadorMore by Mary Ann Meadorhttps://orcid.org/0000-0003-2513-7372Cite this: ACS Mater. Au 2023, 3, 1, 1–7Publication Date (Web):December 8, 2022Publication History Received22 November 2022Published online8 December 2022Published inissue 11 January 2023https://doi.org/10.1021/acsmaterialsau.2c00076Copyright © 2022 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceCC: Creative CommonsBY: Credit must be given to the creatorNC: Only noncommercial uses of the work are permittedND: No derivatives or adaptations of the work are permittedArticle Views3913Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (13 MB) Get e-AlertsSUBJECTS:Biomaterials,Chemical engineering and industrial chemistry,Electrical energy,Materials,Materials science Get e-Alerts

Monolithic aerogels provide superior thermal insulation compared to other forms of aerogel (composites, particulate, etc.). It has also been demonstrated that monolithic aerogels can be made mechanically stronger and more durable by incorporating a conformal polymer coating on the skeletal nanostructure. However, for many applications, it would be most desirable to have monolithic aerogels in a more flexible form, for example, as insulation in deployable and inflatable structures or space suits or to wrap around a structure needing insulation. To this end, it has been found that by incorporating organic linking groups or alkyl trialkoxysilanes into the silica backbone, elastic recovery and/or flexibility is improved, while strength is increased by the use of polymer reinforcement.

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTACS Materials Au: Volume 2, Issue 2 Highlights and a Big Thank You for Nominating 2022 Rising Stars!Stephanie L. Brock*Stephanie L. Brock*Email: [email protected]More by Stephanie L. Brockhttps://orcid.org/0000-0002-0439-302X, Maksym V. KovalenkoMaksym V. KovalenkoMore by Maksym V. Kovalenkohttps://orcid.org/0000-0002-6396-8938, and Mary Ann MeadorMary Ann MeadorMore by Mary Ann Meadorhttps://orcid.org/0000-0003-2513-7372Cite this: ACS Mater. Au 2022, 2, 2, 72–73Publication Date (Web):March 9, 2022Publication History Published online9 March 2022Published inissue 9 March 2022https://doi.org/10.1021/acsmaterialsau.2c00018Copyright © 2022 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceCC: Creative CommonsBY: Credit must be given to the creatorNC: Only noncommercial uses of the work are permittedND: No derivatives or adaptations of the work are permittedArticle Views763Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts Get e-Alerts

[This corrects the article DOI: 10.1021/acsmaterialsau.1c00061.].

Flexible, conformal polyimide (PI) aerogels with low density, good mechanical properties, and high surface areas have attracted much attention for many potential applications such as lightweight antenna substrates, insulating materials for launch vehicles, inflatable structures, aircraft, or space suits. Development and improvements to the fabrication of polyimide aerogel thin films have been reported over the last decade to meet the needs of many of these applications. However, most starting materials are expensive. In this research, we utilized commercially available, low-cost monomers including 4,4'-bis(4-aminophenoxy) propane (BAPP) and 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and 4,4-methylene diphenyl diisocyanate (MDI) in fabricating polyimide (PI) and poly(imide-urea) (PIU), which were then cross-linked with 1,3,5-tris(4-aminophenoxy)benzene (TAB). It was found that the addition of MDI into the PI chains not only maintained the flexibility of the aerogel films but also enhanced the film casting, allowing the production on pilot scale. With the capability of producing robust films at affordable cost, the application of the PIU aerogel films can be expanded to terrestrial goods such as winter clothing, or pipe wrapping, etc. In addition, the presence of only a small addition of the urea links in the polyimide chains in PIU aerogels led to lower shrinkage when compared to the corresponding PI aerogels, leading to lower density.

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTACS Materials Au: Open for YouStephanie L. Brock*Stephanie L. Brock*Email: [email protected]More by Stephanie L. Brockhttps://orcid.org/0000-0002-0439-302X, Maksym V. KovalenkoMaksym V. KovalenkoMore by Maksym V. Kovalenkohttps://orcid.org/0000-0002-6396-8938, and Mary Ann MeadorMary Ann MeadorMore by Mary Ann Meadorhttps://orcid.org/0000-0003-2513-7372Cite this: ACS Mater. Au 2021, 1, 1, 1–2Publication Date (Web):September 8, 2021Publication History Published online8 September 2021Published inissue 8 September 2021https://doi.org/10.1021/acsmaterialsau.1c00032Copyright © 2021 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceCC: Creative CommonsBY: Credit must be given to the creatorNC: Only noncommercial uses of the work are permittedND: No derivatives or adaptations of the work are permittedArticle Views1007Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSUBJECTS:Interfaces,Gold,Quality management,Biomaterials,Materials Get e-Alerts

Polyimide aerogels using 1,12-dodecyldiamine (DADD), 3,3'-dimethylbenzidine (DMBZ), and 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and cross linked using 1,3,5-triaminophenoxybenzene (TAB) were synthesized. Substitution of the aromatic diamine, DMBZ, with varying amounts of the aliphatic diamine, DADD, increases the flexibility in the backbone structure of the prepared aerogel. These aerogels are also lightweight, low density, have a low dielectric constant, and high modulus. Their overall properties (density, shrinkage, porosity, dielectric constant, water uptake, and modulus) and potential use as a conformal substrate for lightweight, high-performance antennas are discussed.

Highly translucent polyimide aerogels were prepared by combining equimolar amounts of pyromellitic dianhydride, 4,4'-hexafluoroisopropylidene di(phthalic anhydride) (6FDA), and 2,2'-dimethylbenzidine and cross-linking with 1,3,5-benzenetricarbonyl trichloride. A multivariable statistical design of experiments was used to perform a comparison study between three variables used to fabricate the aerogels: formulated repeat unit (n) of polyimide oligomers, 6FDA fraction of total dianhydride (0-50 mol %), and total polymer concentration in solution (7-10 wt %). Polymers with 25 mol % 6FDA in the backbone structure were found to produce polyimide aerogels with high optical transmission and low haze. These aerogels also possessed higher surface areas and very narrow nanoscale pore size distribution. Because of the decreased thermal conductivity with increasing amount of 6FDA in the backbone, these aerogels may find use where the combination of high optical transparency and thermal impedance is desired, such as insulated window panes. To this end, future efforts will focus on reducing the yellow color of the polyimide aerogels.

Aerogels are promising materials for many aerospace applications, including high-performance antennae and flexible insulation, because of their inherent low density and high surface areas. Polymer aerogels, especially polyimide aerogels, provide excellent mechanical properties beyond traditional silica aerogels while maintaining the required thermal stability. Polyimide aerogel surface area, porosity, and pore volume are important properties; however, these measurements are traditionally conducted on the aerogel after removal of the solvent. Because of this, the impact of synthetic control and solvent presence on the nanoscale to mesoscale structure of polyimide aerogels in functional applications is unclear. In this report, we use small-angle neutron scattering to determine the dry and solvated skeletal strut size and composition of polyimide aerogels to deduce the impact of solvation on the structure of complex aerogel struts. Our results show that the aerogel contains a hierarchical assembly of pores, with pores present both within and between the supporting struts. This translates to a material with solvent in the larger pores, as well as absorbed in the supporting polyimide skeleton. The amount of solvent uptake in the struts varies with the solvent and polyimide properties. The insight from these results provides pathways to determine the correlations between aerogel nano- and mesoscale structural characteristics, fabrication processes, and their performance in functional applications such as polymeric battery separators. These results also broaden the characterization tools of polymeric aerogels that differentiate between dry and solvated nano- and mesoscale structures that exist in common operating conditions.