Synthesizing several environmentally friendly flame-retardant additives with high efficiency, including metal–organic frameworks, hydrotalcite, and phyllosilicate-based hybrid materials.

Developing technological procedures and successfully producing nanocomposites exhibiting both high flame retardancy and good mechanical properties.

Evaluating the fire resistance and elucidating synergistic mechanisms of combined flame-retardant additives.

 

 

+ Several metal–organic framework materials suitable for flame-retardant nanocomposites were successfully synthesized, including ZIF-67, ZIF-8, Fe-BDC, and Fe-BDC-NH2. ZIF-67 and ZIF-8 exhibit polyhedral dodecahedral morphologies with particle sizes ranging from 50 to 300 nm. Fe-BDC and Fe-BDC-NH2 possess rhombic hexagonal crystalline structures; Fe-BDC has a length of about 800–1000 nm and an average diameter of approximately 100 nm, while Fe-BDC-NH2 exhibits a length of 150–235 nm and an average diameter of around 60 nm.

 

+ Mg/Al layered double hydroxide (Mg/Al-LDH) nanosheets with a hexagonal plate-like morphology and a well-ordered layered structure were successfully synthesized via a co-precipitation method, with an average diameter of approximately 150 nm and a thickness of about 20 nm. The optimal synthesis conditions were determined to be a Mg²⁺/Al³⁺ molar ratio of 2.5, an aging time of 24 hours, and an aging temperature of 90 °C.

 

+ Nano-aluminum hydroxide (nATH) with a hexagonal platelet morphology was successfully prepared using a hydrothermal method, with particle sizes of approximately 350–450 nm and a thickness of around 30 nm. The optimal synthesis conditions were identified as a hydrothermal temperature of 90 °C and a reaction time of 72 hours.

 

+ Halloysite nanotubes were successfully modified with the flame-retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) via a silane coupling bridge, yielding the hybrid material HNT@DA with an organic content about 10 wt%.

 

+ An inorganic–organic hybrid material based on Mg/Al-LDH intercalated with DOPO was successfully fabricated. The basal spacing of LDH in the DOPO-LDH hybrid material reached 17.5 Å at DOPO/LDH mass ratios of 3:1 and 4:1.

 

+ A MOF-DOPO hybrid material was successfully synthesized through a nucleophilic substitution reaction between Fe-BDC-NH2 and DOPO-Cl. The DOPO content successfully grafted onto the MOF structure reached 7.67 wt%.

 

+ Several high-performance flame-retardant composites were successfully prepared on polymer matrices including polyethylene (PE), polyurethane foam (PU), and epoxy, using environmentally friendly additive systems. Furthermore, the synergistic flame-retardant mechanisms of these additive systems in specific polymer matrices were systematically investigated.

- Flame-retardant nanocomposites based on HDPE were successfully prepared, achieving both high flame retardancy and good mechanical performance. The optimal additive composition consisted of 3 wt% Fe-BDC, 10.2 wt% ATH, and 6.8 wt% red phosphorus (RP). With this formulation, the PE nanocomposite achieved a UL-94 V-0 rating, a limiting oxygen index (LOI) of 27.2%, a tensile strength of 22.48 MPa, and an elongation at break of 527.42%. This optimized formulation was selected as the basis for developing the technological procedure for producing flame-retardant PE nanocomposites that meet all registered technical criteria.

- Flame-retardant PU composites were successfully prepared using a free-foaming method with a combined additive system of expandable graphite (EG) and APP@PEI. The optimal composition included 5 wt% APP@PEI and 15 wt% EG. With this formulation, the PU composite achieved a UL-94 V-0 rating, an LOI value of 31.1%, and a compressive strength of 0.348 MPa. This formulation was selected to establish the technological procedure for producing flame-retardant PU foam composites that meet the registered technical requirements.

- Flame-retardant epoxy nanocomposites were successfully prepared via curing method. The synergistic flame-retardant effects of three additive systems—nATH/APP@PEI, DOPO-LDH/APP@PEI, and MOF-DOPO/APP@UMF—were systematically investigated. The results indicated that the MOF-DOPO/APP@UMF system provided the most outstanding flame-retardant performance in the epoxy matrix. The optimal ratio was determined to be 1 wt% MOF-DOPO and 9 wt% APP@UMF. With this formulation, the epoxy composite achieved a UL-94 V-0 rating, an LOI value of 37.3%, a tensile strength of 60.95 MPa, and an impact strength of 21.12 kJ/m².

 

+ A technological procedure for producing flame-retardant PE nanocomposites was successfully developed at a scale of 1 kg per batch, with the composition consisting of 78.43 wt% HDPE resin, 16.67 wt% aluminum hydroxide/red phosphorus additive system, 2.94 wt% Fe-BDC, and 1.96 wt% paraffin oil.

 

+ A technological procedure for producing flame-retardant PU foam nanocomposites was also established at a scale of 100 g per batch, with the composition including 29.67 wt% polyether polyol, 47.48 wt% 4,4′-diphenylmethane diisocyanate (MDI), 2.08 wt% cyclopentane, 1.48 wt% Polycat 8 catalyst, 14.28 wt% expandable graphite (EG), and 4.83 wt% APP@PEI.

 

+ Several novel hybrid flame-retardant materials based on nano-structured frameworks, including DOPO-LDH, MOF-DOPO, and HNT@DA, were successfully developed. These materials simultaneously exhibit synergistic flame-retardant performance and effective reinforcement capability, demonstrating strong potential for practical applications.

+ A technological  procedure for producing flame-retardant PE nanocomposites was successfully developed at a scale of 1 kg per batch.

+ A technological procedure for producing flame-retardant PU foam nanocomposites was successfully established at a scale of 100 g per batch.

+ Novel flame-retardant additives based on nano-structured hybrid materials, including DOPO-LDH, MOF-DOPO, and HNT@DA, were successfully designed and fabricated. These materials simultaneously exploit the gas-phase flame-retardant activity of DOPO and the condensed-phase barrier effect as well as the reinforcement characteristics of nano-structured materials. As a result, high-performance additive systems were obtained, exhibiting superior efficiency compared with conventional flame-retardant additives.

 

+ The preparation of flame-retardant composites and the optimal formulation of additive combinations for both thermoplastic and thermosetting polymer matrices were systematically investigated, with particular emphasis on achieving a balance between flame-retardant efficiency and the retention of mechanical properties. Specifically, the additive systems consisting of 3 wt% Fe-BDC, 10.2 wt% ATH, and 6.8 wt% RP for PE, 5 wt% APP@PEI and 15 wt% EG for PU foam, and 1 wt% MOF-DOPO and 9 wt% APP@UMF for epoxy were demonstrated to provide outstanding flame-retardant performance while maintaining satisfactory mechanical properties and high potential for practical applications.

 

+ The synergistic flame-retardant mechanisms of these additive systems in specific polymer matrices were systematically elucidated through thermal analysis, structural and morphological characterization of char residues, microstructural observations, and identification of decomposition products. These findings provide deeper insight into the interaction mechanisms among flame-retardant additives and contribute to the rational design of optimized additive systems tailored to the characteristics of different polymer matrice.

 

[1]. Truong Cong Doanh, Nhung Hac Thi, Hong Tham Nguyen, Ho Thi Oanh, Tien Dat Doan, Nguyen Duc Tuyen, Minh-Tan Vu and Mai Ha Hoang. Preparation and synergistic effect of aluminum hydroxide nanoplates on the fire resistance and thermal stability of the intumescent flame retardant epoxy composite. RSC Advances, 2024, 15(21), 16814-16825. (SCIE, IF=4.6, Q1)

[2]. Nhung Hac Thi, Truong Cong Doanh, Hong Tham Nguyen, Ho Thi Oanh, Tien Dat Doan and Mai Ha Hoang. DOPO‐Intercalated layered double hydroxide: A synergistic flame‐retardant nanohybrid for high performance epoxy composite. Journal of Applied Polymer Science, 2026, 143(2), e57993. (SCIE, IF =2.8, Q2)

[3]. Nhung Hac Thi, Hong Tham Nguyen, Tran Duc Long, Ho Thi Oanh, Tien Dat Doan, Giang Le Nhat Thuy, Ha Tran Nguyen, Tuyen Van Nguyen, Mai Ha Hoang. DOPO-functionalized Fe-based metal–organic framework and its synergistic flame retardant effect with microencapsulated ammonium polyphosphate in epoxy composites. RSC Advances, 2025, 15(55), 47587-47600. (SCIE, IF = 4.6, Q1)

 

[1]. Hắc Thị Nhung, Nguyễn Hồng Thắm, Nguyễn Linh Chi, Hồ Thị Oanh, Đoàn Tiến Đạt, Nguyễn Đức Tuyển, Trần Quang Hưng, Trần Quang Vinh, Nguyễn Văn Tuyến, Hoàng Mai Hà. Haloysit gắn dopo ứng dụng nâng cao khả năng chống cháy và cơ tính của hệ compozit polyetylen. Tạp chí Hoá học & Ứng dụng, 2024, 3B (71), 166-172. 

[2]. Nguyen Hong Tham, Nhung Hac Thi, Truong Cong Doanh, Tran Duc Long, Ho Thi Oanh, Tien Dat Doan, Nguyen Duc Tuyen, Minh-Tan Vu, Mai Ha Hoang. Enhancement in the fire resistant efficiency of epoxy resin by synergistic effect between metal-organic frameworks and polyethyleneimine-modified ammonium polyphosphate. Hanoi University of Industry Journal of Science and Technology, 2025, 61(7), 201-211.

 

[1]. NCS. Hắc Thị Nhung, KS. Nguyễn Hồng Thắm, TS. Hồ Thị Oanh, NCS. Đoàn Tiến Đạt, ThS. Nguyễn thị Thu Hiền, CN. Nguyễn Đức Tuyển, PGS. TS. Hoàng Mai Hà. Vật liệu compozit chống cháy hiệu năng cao trên nền nhựa polypropylen, Thương mại hoá kết quả nghiên cứu: Cơ hội và giải pháp, 378-387.

 

[1]. 60 g of metal–organic framework materials suitable for the fabrication of flame-retardant nanocomposites.

[2]. 200 g of nanostructured phyllosilicate minerals modified with organic flame-retardant compounds.

[3]. 1 kg of flame-retardant nanocomposite materials based on polyethylene resin.

[4]. 200 g of flame-retardant nanocomposite materials based on polyurethane foam.

 

[1]. 01 technological procedure for producing flame-retardant nanocomposites based on polyethylene resin at a scale of 1 kg per batch.

[2]. 01 technological procedure for producing flame-retardant nanocomposites based on polyurethane foam at a scale of 100 g per batch.

 

[1]. Truong Cong Doanh has successfully defended his doctoral dissertation at Hanoi University of Industry.

[2]. Hac Thi Nhung has successfully defended his doctoral dissertation at Graduate University of Science and Technology - Vietnam Academy of Science and Technology.

[3]. Mr. Tran Duc Long successfully defended his undergraduate thesis and was awarded a Bachelor’s degree in Chemistry at Hanoi National University of Education.