J. Mater. Sci. Technol. ›› 2024, Vol. 196: 224-236.DOI: 10.1016/j.jmst.2024.01.062

Special Issue: Biomaterials 2024

• Reserch Article • Previous Articles     Next Articles

Enabling simultaneous reprocessability and fire protection via incorporation of phosphine oxide monomer in epoxy vitrimer

Zhenyu Huanga,b, Wenyu Wu Klinglerb,*, Daniele Roncuccib, Carolina Polisib, Valentin Rougierc, Sandro Lehnerb, Milijana Jovicb, Daniel Rentschd, Sithiprumnea Dulb, Karin Brändli Hedlunde, Véronique Michaudc, Zhengzhou Wanga,f,*, Sabyasachi Gaanb,*   

  1. aDepartment of Polymeric Materials, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China;
    bLaboratory for Advanced Fibers, Empa Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, St. Gallen, 9014, Switzerland;
    cLaboratory for Processing of Advanced Composites (LPAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland;
    dLaboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland;
    eInstitute for Materials technology and plastics processing, OST-Eastern Switzerland University of Applied Sciences, 8640 Rapperswil, Switzerland;
    fKey Laboratory of Advanced Civil Engineering Materials, Tongji University, Shanghai, 201804, China
  • Received:2023-09-25 Revised:2023-12-05 Accepted:2024-01-21 Published:2024-10-10 Online:2024-03-14
  • Contact: * E-mail addresses: wenyu.wu@empa.ch (W. Wu Klingler), zwang@tongji.edu.cn (Z. Wang), sabyasachi.gaan@empa.ch (S. Gaan).

Abstract: The conception of epoxy thermosets with both reprocessability and flame retardancy delineates a new horizon in polymer science, offering a material solution that is not only superior in fire safety but is also environment friendly. Herein, a flame-retardant epoxy vitrimer (EV) was prepared using partially bio-based IADPPO (diphenylphosphine oxide itaconic anhydride) and citric acid as curing reagents via a solvent-free process. Their incorporation created covalent adaptable networks (CANs) in the matrix which promote reprocessability and recyclability. The EV exhibits excellent thermal stability with high initial decomposition temperature (T-5wt% ∼308 °C) and high glass transition temperature (Tg ∼107 °C), similar to the blank EV (115 °C). The flame retardancy, mechanical properties, transesterification-based reprocessability, and flame-retardant mechanism were investigated. The EV containing 3 wt% phosphorus (EV IADPPO 3P) achieved UL-94 V0 classification with a limiting oxygen index (LOI) of 27%, while the virgin sample Blank EV (without phosphorus) burned completely. Additionally, increased flexural strength of 79% was observed for EV IADPPO 3P compared to Blank EV. Furthermore, the flame-retardant EV showed high malleability and reparability that could be thermomechanically reprocessed without sacrificing the thermal, mechanical, and flame-retardant properties. Thus, the newly developed epoxy vitrimer is not only fire-safe but fulfills the sustainability goals of today's society.

Key words: Epoxy vitrimer, Covalent adaptable networks, Flame retardancy, Reparable and reprocessable, Bio-based thermoset