Role of morphological arrangements in cellulose nanofiber-based aerogels for thermal insulation: A systematic review

ABSTRACTAerogels are highly porous solid-state structures with low density and have numerous properties, such as high absorption activity, low dielectric constant, high sound absorption, and low thermal conductivity. These properties made aerogels worthwhile as acoustic and thermal insulators, pharmaceutical carriers, flexible energy storage devices, and a template for synthesizing inorganic nanomaterials. From an environmental aspect, biodegradable and green aerogels are in light of the research. Cellulose, extracted from various natural sources, is the most abundant and environmentally benign material employed as a starting material for aerogels. This review provides insights into the introduction of cellulose nanofiber aerogels and their fabrication processes using various pre-treatment techniques, such as enzymatic, chemical, or ionic-liquid methods, and several drying methods. Following this, the properties, thermal performance, and morphology that affects the thermal insulation of nano-fibrillated cellulosic aerogels are discussed. Owing to their outstanding thermal insulating properties, nano-fibrillated cellulose aerogels would be a potential choice for insulation in building applications. The steps toward sustainability require such resource-bounded research development.KEYWORDS: Aerogelsnano-fibrillated celluloserenewablemorphologythermal insulation AcknowledgementsThis study was supported by the project from the Science and Engineering Research Board, Government of India, India (Grant No. CRG/2021/004515). With a contingency grant number (PM-31-22-728-414), the author, Shakshi Bhardwaj, appreciates financial support from the Prime Minister Research Fellowship Program, Government of India.Disclosure statementThe authors are aware of no personal or financial conflicts that may affect the research reported in this study.Abbreviations SiC-=Silicon carbideSiOC-=Silicon oxycarbideSiCN-=Silicon carbonitrideRF-=Resorcinol formaldehydeMF-=Melamine formaldehydeCNCs-=Cellulose nanocrystalsNFC-=Nano-fibrillated CelluloseBNC-=Bacterial nanocelluloseGOs-=Graphene oxide sheetsMTMS-=MethyltrimethoxysilaneSGB-=Sugarcane bagasse aerogelsFESEM-=Field emission scanning electron microscopyAFM-=Atomic force microscopyXMT-=X-ray microtomographyPPy-=PolypyrrolePU-=PolyurethaneBCF-=Bleached cellulose fibersCDBAs-=Diacetate-based aerogelsTDI- 2=2,4-toluene diisocyanateMoS2-=Molybdenum disulfideLOI-=Limiting oxygen indexCDA-=Cellulose diacetatePMSQ-=PolymethylsilsesquioxaneMTMS-=MethyltrimethoxysilaneZB-=Zinc borateMMT-=MontmorilloniteGO-=Graphene oxidePI-=PolyimideBC-=Bacterial celluloseCA-=Aramid fibersNFA-=Nanofiber aerogelsWH-=Water hyacinthPVA-=Polyvinyl acetatePS-=PolystyreneTGA-=Thermogravimetric analysisMUF-=Melamine – urea–formaldehydePPMS-=Pentaerythritol phosphate melamine saltSBC-=Sodium bicarbonateCAAs-=Cellulose acetate aerogelsPFDS-=PerfluorodecyltriethoxysilaneHMDS-=HexamethyldisilazaneMTES-=MethyltriethoxysilaneFS-=Fumed silicaData availability statementNo data was used for the research described in the article.Additional informationFundingFunding for this research study was supplied by the funding-source; Science and Engineering Research Board of the Government of India (Grant No. award-id CRG/2021/004515), India, as part of the initiative. 2. The Prime Minister Research Fellowship Program, Government of India, provided financial support to the author, Shakshi Bhardwaj, with a contingency grant number (PM-31-22-728-414).