Proof of ether-bridged condensation products in UF resins by 2D NMR spectroscopy

• Published in: Journal of polymer research Vol. 20; no. 4; pp. 1 - 10
• Main Authors: Kibrik, Éléonore J., Steinhof, Oliver, Scherr, Günter, Thiel, Werner R., Hasse, Hans
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.04.2013; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensates; Condensation resins; Correlation; Industrial Chemistry/Chemical Engineering; NMR spectroscopy; Original Paper; Polymer Sciences; Polymers; Resins; Spectroscopy; Two dimensional; Urea; NMR; Resins; Structure; Condensation; Formaldehyde
• ISSN: 1022-9760; 1572-8935
• DOI: 10.1007/s10965-013-0079-7

The existence of ether-bridged condensation products in urea-formaldehyde (UF) resins is still disputed in the literature as these products have never been isolated or fully characterized. Using 1 H- 15 N gradient heteronuclear single quantum correlation (gHSQC) experiment, 1 H- 13 C gHSQC experiment and 1 H- 13 C gradient heteronuclear multiple bond correlation (gHMBC) experiment a, methylolurea hemiformal compound (urea compound with oligomeric chains and ) and a symmetrical compound, most likely an ether-bridged condensation product, in a UF resin sample were characterized. The results were confirmed by 2D NMR 13 C- 13 C gradient correlated spectroscopy (gCOSY) experiment using 13 C labeled ureaformaldehyde samples. Spectroscopic chemical shifts of the proposed ether-bridged condensation product in 15 N, 13 C, 1 H NMR spectroscopy were assigned. Furthermore, individual peak assignments are provided for the methylolurea hemiformal moiety.