DOPO-HQ

Catalog NumberACM99208501-1

CAS Number99208-50-1

CategoryDOPO Flame Retardant

Description	DOPO-HQ is a newly-designed,non-halogenated flame retardant. Due to the rigidbiphenyl,the phosphorus moiety，and the reactive phenol group,DOPO-HQ cancrosslink with epoxy resins to enhance the fire-resistancy, thermal stability, and solvent-resistancy of polymers. Furthermore, DOPO-HQ is environmentally friendly since itdoes not emit toxic hydrochloric or hydrobromic gas under flame.
Synonyms	10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, Flame retardant DOPO-HQ (HCA-HQ)
Molecular Weight	324.27
Molecular Formula	C18H13O4P
Boiling Point	592.9±60.0 °C
Melting Point	245-255 °C
Purity	99% min
Density	1.49±0.1 g/cm³(Predicted)
Appearance	White powder
Application	In epoxy resin, It can be widely used in the flame retardant of the polymermaterials of the sealed, potting of the electronic components. It is widely used in semiconductor material encapsulation, printed substrate,and other fields.

Download COA Download MSDS

Case Study

Enhancing PLA Flame Retardancy with DOPO-HQ Functionalized Graphene Oxide

Shi, Xingxing, et al. Journal of colloid and interface science 524 (2018): 267-278.

Polylactic acid (PLA) is a highly flammable and smoke-producing biodegradable polymer with poor fire resistance properties. A novel nanohybrid flame retardant (FGO-HQ) was engineered by functionalizing graphene oxide (GO) with DOPO-HQ (10-(2,5-dihydroxyl phenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide). This design leverages dual-phase flame inhibition, including GO's barrier effect in condensed phase and DOPO-HQ's radical quenching in gas phase.
Synthesis & Characterization: GO was acylated with thionyl chloride, then functionalized with DOPO-HQ via reflux in THF. FGO-HQ was melt-blended with PLA at 6 wt% concentration using an internal mixer (180°C, 10 min), followed by hot-pressing. Performance was evaluated through UL-94, cone calorimetry (PHRR, THR, SPR, TSR), TG-IR, Raman spectroscopy, SEM, FT-IR, and tensile strength.
Key Results:
· Fire Safety Performance (6 wt% FGO-HQ): Achieved UL-94 V-0 rating; PHRR reduced by 24.0%, THR by 43.0%; SPR decreased 46%, TSR decreased 83%.
· Mechanism Validation: TG-IR/FT-IR verified gas-phase radical scavenging by phosphorus species, reducing flammable volatiles. SEM/Raman revealed enhanced graphitized char with phosphorus-aromatic networks acting as a thermal shield.
· Material Integrity: Mechanical properties (tensile strength) of PLA were preserved post-addition.

Optimizing PBT Flame Retardancy with DOPO-HQ/PTW Synergy

He, Min, et al. Polymer Composites 40.3 (2019): 974-985.

Polybutylene terephthalate (PBT) needs to improve flame retardancy for demanding applications. 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) was used along with reactive compatibilizer poly(ethylene-butylacrylate-glycidylmethacrylate) (PTW) to crosslink on heating during combustion. The two-additive system was designed to provide two modes of flame retardancy: gas-phase radical quenching (DOPO-HQ) and condensed-phase crosslinked char reinforcement (PTW).
Preparation: PBT composites were prepared via twin-screw extrusion. PBT and DOPO-HQ (pre-dried) were melt-blended at 0-20 wt% loadings. An optimized composition was found to be 20 wt% DOPO-HQ + 5 wt% PTW. Injection-molded specimens were tested in UL-94, LOI, and cone calorimetry according to standard procedures.
Key Results:
· The PTW-compatibilized system achieved UL-94 V-0 (no dripping), significantly increased LOI, and reduced key fire metrics: 50% lower PHRR, 28% lower THR, and >28% reductions in Av-HRR/FIGRA/MAHRE.
· Analysis confirmed dual mechanisms: gas-phase PO·/PO2· radical quenching (via TG-FTIR) and condensed-phase crosslinked char reinforcement (via Raman/SEM), with increased activation energy (Ea) suppressing decomposition.

High-Performance Epoxy Systems by DOPO-HQ/Siloxane Synergism

Ji, Yundong, et al. High Performance Polymers 37.3 (2025): 169-182.

Industrial uses (shipbuilding, aerospace) often require epoxy resin materials with simultaneously improved mechanical properties and high flame retardancy. A silicon-phosphorus hybrid epoxy (ED/EB) was prepared by chemically incorporating DOPO-HQ (source of phosphorus) and a hydroxyl-terminated silicone oligomer (Z-6018) into epoxy resin (E-51). Synergistic combination of the two modifiers was designed to satisfy the demands of mechanical performance and fire safety in one resin.
Synthesis & Characterization: ED/EB resin was synthesized by chemical modification of DOPO-HQ and Z-6018 precursors. Evaluation included mechanical tests (tensile and impact strength), flame retardancy tests (LOI, FIGRA, smoke suppression), and char residue evaluation.
Key Results:
· Improved Mechanical Properties: Tensile strength +16.7%, Impact strength +20.7%. Synergistic effect of silicon and phosphorus achieved toughening and strengthening effects on the same resin.
· Flame Retardancy: High LOI (from DOPO-HQ) and superior smoke suppression (from silicone) with reduced flame growth index (FIGRA).
· SEM of post-combustion residue showed a compact protective char layer, which regulated smoke particle release and increased the residual mass.

If the product of interest is not available in our catalog, please contact us to see if there is any relevant stock or other purchase channels.