Qi Zhang

In this study, a novel flame retardant designated as SFD, which contains phosphorus (P), nitrogen (N), and sulfur (S), was successfully synthesized via a one-pot method utilizing 2-aminobenzothiazole, furfural, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials. This flame retardant was subsequently incorporated as an additive into epoxy resin (EP), with various formulations prepared using dicyandiamide (DDM) as the curing agent. The epoxy formulations containing only 3 wt% of SFD exhibited an improved Limiting Oxygen Index (LOI) of 34% and achieved UL-94 V-0 ratings. The Peak Heat Release Rate (PHRR), Total Heat Release (THR), and Total Smoke Production (TSP) for the EP/SFD composites were reduced by 28.0%, 30.1%, and 30.0%, respectively, in comparison to pure EP. Mechanical property assessments of the SFD/EP composites indicated that the incorporation of SFD had minimal impact on the mechanical properties of EP; thus, SFD can enhance the flame retardancy of EP without compromising its mechanical integrity. Analysis of the flame retardant mechanism revealed a significant P-N synergistic effect between the benzothiazole moiety and the phosphorus heterophenanthrene moiety present in SFD. The addition of SFD effectively mitigates heat release and smoke production during combustion processes involving EP while demonstrating excellent flame-retardant characteristics along with smoke suppression capabilities; furthermore, it promotes carbon layer formation. This research presents a straightforward strategy for synthesizing a multi-element synergistic flame retardant system that holds promise for application across a broad spectrum of thermoset plastics.

A co-polymerization–carbonization method was employed to synthesize porous carbon nanospheres (PCNSs) using pyrrole–aniline polymers as a carbon source and alkyl phenol non-ionic surfactants as templates. The effect of the hydrophilic length on the carbon nanosphere size was systematically investigated. The so-prepared PCNSs were characterized via high-magnification scanning electron microscopy, dynamic light scattering (DLS) analysis, and N₂ adsorption and desorption analysis. The results indicate that the obtained nanosphere diameter can be tuned by changing the length of the hydrophilic groups. The length of the hydrophilic groups mainly affects the size of the vesicles or micelles formed by the assembly of the surfactant in solution, as was verified by the DLS results. After activation by KOH, the typical sample EO(30)–PCNS has a high specific surface area of 2137 m²/g and a large pore volume of 1.76 cm³/g. Electrochemical tests in 6 M KOH demonstrated that the assembled EO(30)–PCNS supercapacitor electrode displays good capacitive properties, such as a high specific capacitance of 221 F/g at 1.0 A/g and a good rate capacity of 68% retention at 10.0 A/g. This finding suggests that the uniform particle shape and high specific surface area are beneficial for the ion transportation, leading to good electrochemical performances. Our work provides a novel synthetic strategy for the fabrication of carbon nanospheres or other nanosphere materials for the construction of high-performance supercapacitors by optimizing few parameters, such as the length of the hydrophilic or hydrophobic groups of the surfactants.

A series of novel cationic gemini surfactants p‐phenylenedimethylene bis(alkyldiethylammonium) chloride (abbreviated as G_m, m is the carbon numbers of hydrophobic tails) were synthesized. Their surface properties and aggregation behavior were investigated by surface tension, electrical conductivity, steady‐state fluorescence, dynamic light scattering and transmission electron microscopy measurements, and compared with gemini surfactants with a flexible hexanediyl spacer and diethylammonium headgroups [abbreviated as C_mC₆C_m(Et)]. It was found that G_m reached adsorption equilibrium at the air–water interface at the critical micelle concentration, but C_mC₆C_m(Et) did not. The packing densities and the aggregation surface charge densities of G_m are less than that of C_mC₆C_m(Et). Pre‐micellar association occurs in aqueous solutions of gemini surfactants with m ≥ 14. The ability to form pre‐micellar aggregates increases with increasing the length of alkyl chain. Gemini surfactants with rigid p‐xylylene spacer are more prone to form the pre‐micellar aggregates. The rigidity of the spacer of gemini surfactants has little effect on the aggregation micropolarity sensed by pyrene. Only vesicles were found in aqueous solutions of these gemini surfactants, and G_m with p‐xylylene spacer tends to form larger vesicles which have loose structures with low surface charge density.