Open Access

ARTICLE

Reactive Integration of Amino-Functional 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-modified metal–organic frameworks (MOFs) into Polyurea Balancing Flame Retardancy and Mechanical Properties

Yifan Wang¹, Xishun Qiu¹, Chao Wu¹, Jiazhao Li¹, Chang Dai¹, Bowen Han¹, Jinhu Hu², Mingliang Ma^1,*, Ye-Tang Pan^2,*
1 School of Civil Engineering, Qingdao University of Technology, Qingdao, China
2 National Engineering Research Center of Flame Retardant Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing, China
* Corresponding Author: Mingliang Ma. Email: ; Ye-Tang Pan. Email:
(This article belongs to the Special Issue: The Application of Polymer-based Nanomaterials for Fire Safety)

Journal of Polymer Materials https://doi.org/10.32604/jpm.2026.076443

Received 20 November 2025; Accepted 04 February 2026; Published online 18 March 2026

Abstract

Polyurea (PUA) is widely valued in protective coatings and structural reinforcement because of its impressive mechanical strength and resistance to corrosion. Its high flammability, together with the poor dispersion that often comes with simply blending in flame retardants, continues to limit its use in demanding environments. To overcome these issues, this study introduces a different approach. We grafted 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) onto the surface of a metal–organic framework (MOF) and then partially amino-functionalized the DOPO layer, ultimately creating an amino-modified DOPO–MOF hybrid. The introduced amino groups can directly react with the isocyanate (–NCO) groups in the PUA matrix, allowing the flame-retardant component to be integrated via reactive integration rather than physical blending. This approach helps avoid the interfacial defects and the mechanical weakening typically observed in conventional blending. With 5 wt% ZIF-67@DOPO-NH₂ added to the PUA system, the composite successfully reached a UL-94 V-0 classification and showed a notable increase in limiting oxygen index (LOI), from 19.2% to 23.8%. The peak heat release rate and total heat release dropped by 36.3% and 38.7%, respectively. Meanwhile, the tensile strength decreased from 25.74 to 22.52 MPa, while the elongation at break remained above 300%, indicating that the material maintained excellent toughness.

---

Keywords

PUA; DOPO; MOFs; flame retardancy; mechanical properties

---