Title: Condensation reaction pathway of free formaldehyde and surface hydroxyl groups of nano-TiO₂

Authors: Li Lyu; Binxu Xie; Shuangshuang Wang

Addresses: Guangxi Minzu Normal University, Chongzuo, 532200, Guangxi, China ' Beijing East Simulation & Control Technology Co., Ltd., Beijing, 100029, China ' Beibu Gulf University, Qinzhou, 535011, Guangxi, China

Abstract: This study aims to investigate the specific pathways and mechanisms of the condensation reaction between free formaldehyde and hydroxyl groups on the surface of nano TiO₂. Firstly, free formaldehyde and nano TiO₂ are applied to the urea formaldehyde resin system and subjected to condensation reaction at a constant temperature. Secondly, Fourier transform infrared spectroscopy (FTIR) is used to track the evolution of characteristic hydroxyl peaks during the reaction process. In addition, solid-state nuclear magnetic resonance (NMR) is used to detect newly formed methylene bridge structures in condensation systems. Finally, the thermal decomposition of the resin after the reaction is simultaneously monitored using thermogravimetric differential scanning calorimetry (TG-DSC). The results showed that DFT simulation successfully identified the key transition state TS1, with a maximum reaction potential barrier of 0.87 eV and a methylene bridge content of up to 45.3%.

Keywords: free formaldehyde condensation reaction; nano-TiO₂ surface hydroxyl groups; UF resin structure; thermal stability analysis; density functional theory simulation.

DOI: 10.1504/IJMMP.2025.155472

International Journal of Microstructure and Materials Properties, 2025 Vol.18 No.4, pp.281 - 301

Received: 24 Sep 2025
Accepted: 30 Apr 2026
Published online: 03 Aug 2026 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article