Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution
Abstract Inverse freezing fluids (IFF) are the new field of science that thermodynamically acts opposite to conventional fluids. These IFFs are novel artificial materials that work as typical thermal metamaterials. This paper reports the IFF phenomenon with basic chemicals such as citric acid and et...
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Springer
2025-01-01
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| Series: | Discover Materials |
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| Online Access: | https://doi.org/10.1007/s43939-025-00192-z |
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| author | Reshma Karunakaran Rajagopal Shanmugasundaram |
| author_facet | Reshma Karunakaran Rajagopal Shanmugasundaram |
| author_sort | Reshma Karunakaran |
| collection | DOAJ |
| description | Abstract Inverse freezing fluids (IFF) are the new field of science that thermodynamically acts opposite to conventional fluids. These IFFs are novel artificial materials that work as typical thermal metamaterials. This paper reports the IFF phenomenon with basic chemicals such as citric acid and ethanolamine subjected to different conditions. The amine molecule within the precursor compound is crucial in attaining this phenomenon. Its respective inter and intramolecular ‘hydrogen’ atoms remain the key reason for this effect. Results of rheometry, Raman, proton nuclear magnetic resonance (1HNMR), photoluminescence (PL) spectroscopy, and thermogravimetric analysis (TGA) of this fluid confirmed this phenomena, collectively. Experimental findings confirm the reversible phase transformation which is contrary to the conventional fluids. It will open the interest in finding new thermal metamaterials. This study can be considered the first attempt at synthesizing IFFs through a new preparation method and analysed in detail. Many challenges were faced during synthesis and characterizations, so this study will help to resolve the complexity in this domain. Further, the sample was sintered and found to be multi-layered reduced graphene oxide (rGO) powder. This rGO sample’s structural, chemical nature, and morphology are studied through x-ray diffraction (XRD), Fourier transformed infra-red (FTIR), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope imaging and energy dispersive analysis of x-rays (EDAX). XRD pattern confirmed the presence of the main peak at 26° (2θ) corresponding to the basal reflection (002) of rGO phase. It was further evidenced by its D and G bands of Raman spectra at 1357 and 1574 cm−1, respectively. FTIR analysis also revealed a reduced OH- band whereas EDAX analysis confirms the purity of rGO by the presence of carbon and oxygen peaks only. Multilayer formation of rGO was confirmed by SEM and TEM observations and found that the measured thickness of the sheet was nearly 1 nm. Graphical Abstract |
| format | Article |
| id | doaj-art-8afdd09692d74cff8f0b5659198632ec |
| institution | Kabale University |
| issn | 2730-7727 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Springer |
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| series | Discover Materials |
| spelling | doaj-art-8afdd09692d74cff8f0b5659198632ec2025-01-26T12:57:32ZengSpringerDiscover Materials2730-77272025-01-015111610.1007/s43939-025-00192-zInsight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solutionReshma Karunakaran0Rajagopal Shanmugasundaram1Department of Physics and Electronics, School of Sciences, Jain (Deemed to be) UniversityDepartment of Physics and Electronics, School of Sciences, Jain (Deemed to be) UniversityAbstract Inverse freezing fluids (IFF) are the new field of science that thermodynamically acts opposite to conventional fluids. These IFFs are novel artificial materials that work as typical thermal metamaterials. This paper reports the IFF phenomenon with basic chemicals such as citric acid and ethanolamine subjected to different conditions. The amine molecule within the precursor compound is crucial in attaining this phenomenon. Its respective inter and intramolecular ‘hydrogen’ atoms remain the key reason for this effect. Results of rheometry, Raman, proton nuclear magnetic resonance (1HNMR), photoluminescence (PL) spectroscopy, and thermogravimetric analysis (TGA) of this fluid confirmed this phenomena, collectively. Experimental findings confirm the reversible phase transformation which is contrary to the conventional fluids. It will open the interest in finding new thermal metamaterials. This study can be considered the first attempt at synthesizing IFFs through a new preparation method and analysed in detail. Many challenges were faced during synthesis and characterizations, so this study will help to resolve the complexity in this domain. Further, the sample was sintered and found to be multi-layered reduced graphene oxide (rGO) powder. This rGO sample’s structural, chemical nature, and morphology are studied through x-ray diffraction (XRD), Fourier transformed infra-red (FTIR), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope imaging and energy dispersive analysis of x-rays (EDAX). XRD pattern confirmed the presence of the main peak at 26° (2θ) corresponding to the basal reflection (002) of rGO phase. It was further evidenced by its D and G bands of Raman spectra at 1357 and 1574 cm−1, respectively. FTIR analysis also revealed a reduced OH- band whereas EDAX analysis confirms the purity of rGO by the presence of carbon and oxygen peaks only. Multilayer formation of rGO was confirmed by SEM and TEM observations and found that the measured thickness of the sheet was nearly 1 nm. Graphical Abstracthttps://doi.org/10.1007/s43939-025-00192-zInverse freezingFluidRheometerProton NMRViscosityGraphene oxide |
| spellingShingle | Reshma Karunakaran Rajagopal Shanmugasundaram Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution Discover Materials Inverse freezing Fluid Rheometer Proton NMR Viscosity Graphene oxide |
| title | Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| title_full | Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| title_fullStr | Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| title_full_unstemmed | Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| title_short | Insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| title_sort | insight into unusual complex thermodynamical behaviour of citric acid and ethanolamine solution |
| topic | Inverse freezing Fluid Rheometer Proton NMR Viscosity Graphene oxide |
| url | https://doi.org/10.1007/s43939-025-00192-z |
| work_keys_str_mv | AT reshmakarunakaran insightintounusualcomplexthermodynamicalbehaviourofcitricacidandethanolaminesolution AT rajagopalshanmugasundaram insightintounusualcomplexthermodynamicalbehaviourofcitricacidandethanolaminesolution |