Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway
Industrial polyureas are typically synthesized using diisocyanates via two possible alternative pathways: the extremely quick and highly exothermal diamine–diisocyanate pathway and the relatively slow and mild water–diisocyanate pathway. Although polyurea synthesis via the water–diisocyanate pathway...
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MDPI AG
2023-08-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/15/17/3524 |
| _version_ | 1797581995666046976 |
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| author | Theodor Stern |
| author_facet | Theodor Stern |
| author_sort | Theodor Stern |
| collection | DOAJ |
| description | Industrial polyureas are typically synthesized using diisocyanates via two possible alternative pathways: the extremely quick and highly exothermal diamine–diisocyanate pathway and the relatively slow and mild water–diisocyanate pathway. Although polyurea synthesis via the water–diisocyanate pathway is known and has been industrially applied for many decades, there is surprisingly very little analytical information in the literature in relation to the type and extent of the occurring side reactions and the resulting chemical structures following this synthesis pathway. The synthesis of polyureas exhibiting very high concentrations of carbonyl-containing groups resulted in strong and accurate diagnostic analytical signals of combined FTIR and solid-state <sup>13</sup>C NMR analysis. Despite the strictly linear theoretical chemical structure designed, the syntheses resulted in highly nonlinear and crosslinked polymers. It was analytically found that the water–diisocyanate pathway preferentially produced highly dominant and almost equal contents of both biuret structures and tertiary oligo-uret structures, with a very small occurrence of urea groups. This is in strong contrast with the chemical structures previously obtained via the diamine–diisocyanate polyurea synthesis pathway, which almost exclusively resulted in biuret structures. The much slower reaction and crosslinking rate of the water–diisocyanate synthesis pathway enabled the further access of isocyanate groups to the already-formed secondary nitrogens, thus facilitating the formation of complex hierarchical tertiary oligo-uret structures. |
| first_indexed | 2024-03-10T23:14:32Z |
| format | Article |
| id | doaj.art-8d0ad3e7b6aa41c7b6694f4b4c4f7e91 |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-10T23:14:32Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-8d0ad3e7b6aa41c7b6694f4b4c4f7e912023-11-19T08:42:51ZengMDPI AGPolymers2073-43602023-08-011517352410.3390/polym15173524Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis PathwayTheodor Stern0Department of Chemical Engineering, Biotechnology and Materials, Faculty of Engineering, Ariel University, Ariel 40700, IsraelIndustrial polyureas are typically synthesized using diisocyanates via two possible alternative pathways: the extremely quick and highly exothermal diamine–diisocyanate pathway and the relatively slow and mild water–diisocyanate pathway. Although polyurea synthesis via the water–diisocyanate pathway is known and has been industrially applied for many decades, there is surprisingly very little analytical information in the literature in relation to the type and extent of the occurring side reactions and the resulting chemical structures following this synthesis pathway. The synthesis of polyureas exhibiting very high concentrations of carbonyl-containing groups resulted in strong and accurate diagnostic analytical signals of combined FTIR and solid-state <sup>13</sup>C NMR analysis. Despite the strictly linear theoretical chemical structure designed, the syntheses resulted in highly nonlinear and crosslinked polymers. It was analytically found that the water–diisocyanate pathway preferentially produced highly dominant and almost equal contents of both biuret structures and tertiary oligo-uret structures, with a very small occurrence of urea groups. This is in strong contrast with the chemical structures previously obtained via the diamine–diisocyanate polyurea synthesis pathway, which almost exclusively resulted in biuret structures. The much slower reaction and crosslinking rate of the water–diisocyanate synthesis pathway enabled the further access of isocyanate groups to the already-formed secondary nitrogens, thus facilitating the formation of complex hierarchical tertiary oligo-uret structures.https://www.mdpi.com/2073-4360/15/17/3524polyureacrosslinkingexpanded polyureaFTIRNMRpolymerization mechanism |
| spellingShingle | Theodor Stern Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway Polymers polyurea crosslinking expanded polyurea FTIR NMR polymerization mechanism |
| title | Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway |
| title_full | Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway |
| title_fullStr | Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway |
| title_full_unstemmed | Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway |
| title_short | Chemical Structure and Side Reactions in Polyurea Synthesized via the Water–Diisocyanate Synthesis Pathway |
| title_sort | chemical structure and side reactions in polyurea synthesized via the water diisocyanate synthesis pathway |
| topic | polyurea crosslinking expanded polyurea FTIR NMR polymerization mechanism |
| url | https://www.mdpi.com/2073-4360/15/17/3524 |
| work_keys_str_mv | AT theodorstern chemicalstructureandsidereactionsinpolyureasynthesizedviathewaterdiisocyanatesynthesispathway |