Hybrid films of novel fluorinated polyimides and hyperbranched cyclotriphosphazene polymer for enhanced flame retardancy, thermomechanical properties, and reduced dielectric constant

This study synthesizes novel polyimide (B2FO PI) films using 4,4'-(1,4-phenyleneisopropylidene)diphenoxy bis(2-(trifluoromethyl)-4-aminobenzene) (B2FDA) and 4,4'-oxydiphthalic anhydride (ODPA), as well as polyimide (PI) hybrid films incorporating a hyperbranched fluorinated cyclotriphosphazene polymer. The findings indicate that incorporating the hyperbranched cyclotriphosphazene significantly enhances the hybrid films' performance by increasing the cross-linking density of the polyimide chains. Moreover, the hybrid PI films demonstrate excellent water resistance, superior thermomechanical properties, enhanced flame-retardant characteristics, and a low dielectric constant.

Fire retardant polyethylene terephthalate containing 4,4′-(hexafluoroisopropylidene)diphenol-substituted cyclotriphosphazene microspheres

Polyphosphazene derivatives are gaining popularity due to their eco-friendly character and high content of flame-retardant components. Herein, a polyphosphazene derivative (PZAF) microsphere was successfully synthesized utilizing an in-situ template approach, which was then employed as an additive flame retardant in polyethylene terephthalate (PET) to improve the fire safety. Thermogravimetric analysis revealed that PZAF promoted the pyrolysis of PET in advance to generate a stable char layer that protects the matrix from heat, consequently increasing char residues. With addition of 10 wt% PZAF, the PET nanocomposites obtained a V-0 grade in vertical combustion test and its LOI value increased from 24.2 vol% to 32.1 vol%. Moreover, the peak heat release and carbon monoxide production decreased by 46.6% and 50.6%, respectively. This was because the phosphonic acid fragments and pyridine ring compounds produced by the PZAF pyrolysis encouraged the development of a robust char layer. Meanwhile, the •PO radicals generated by the pyrolysis of PZAF could capture free radicals in the gas phase, ultimately ending the chain reaction of combustion. Also, mechanical properties of the PET nanocomposites were noticeably enhanced by the addition of 3 or 5 wt% PZAF.

Superhydrophobic fluorinated microspheres for fluorous affinity chromatography

Fluorous affinity chromatography has received growing attention in separation and purification of fluoro compounds, but the wettability of the fluorinated stationary phases is seldom noticed. Here, we construct a series of micro-sized fluorine-containing microspheres by solvothermal precipitation polymerization. The fluorinated microspheres could be obtained with narrow size distribution at even high monomer loading of 15 wt%. Through alternating fluoro monomer, both the particle size and the wettability of the microsphere array could be tuned. Among them, the poly(divinylbenzene -dodecafluoroheptyl methacrylate), P(DVB-DFHMA), microsphere (6.1 μm) arrays displays superhydrophobicity with 153.2° water contact angle. The P(DVB-DFHMA) fluorinated microspheres (7.58% fluorine content) can be packed into steel-less columns as stationary phase for high-performance liquid chromatography. The retention mechanism of the fluorinated column is proven to be the specific fluorine-fluorine interaction. Compared to the commercial C18 silica column, the fluorinated column can completely separate fluorine-containing compounds under high water content mobile phase, including small fluoro molecules and fluoro macromolecules, at much lower back pressure by fluorous affinity.

High-Performance Electrochromic Covalent Hybrid Framework Membranes via a Facile One-Pot Synthesis

Porous framework materials have sparked enormous interest in the electrochromic field, as they possess intrinsic high porosity and a large surface area that are beneficial for electron and ion transport. However, the fabrication of these porous framework materials often requires multiple processing steps or harsh reaction conditions, which significantly limit large-scale fabrication of such materials. In this work, we report a one-pot in situ polycondensation method to construct electrochromic covalent hybrid framework membranes via nucleophilic substitutions between hexachlorocyclotriphosphazene (HCCP) and triphenylamine (TPA) in an ambient environment. With the high transparency of polyphosphazene in a wide optical range, the constructed phosphazene-triphenylamine (PPTA) covalent hybrid framework membranes can be reversibly switched between light gray and dark blue, with a high transmittance change of up to 79.8%@668 nm and fast switching time (<4 s). Owing to the easy one-pot fabrication and good electrochromic properties, the PPTA covalent hybrid framework membrane has great potential in various fields such as displays and dynamic optical windows.

Manipulating Nano-suspension Droplet Evaporation by Particle Surface Modification

The evaporation of a nano-suspension droplet on a substrate has gained extensive attention recently due to its potential application in the rising industry of functional coating. In this paper, we reported that the droplet evaporation behavior can be controlled by the nanoparticles' concentration and the functional group on the surface of nanoparticles. Experimental results indicated that the suspension of nanoparticles notably enhanced the evaporation rate of droplets and decreased the duration time of the continuous-contact-radius (CCR) stage. This effect was more obvious when the nanoparticles were modified by the perfluorodecyltrimethoxysilane (PDTS), which made the particles more hydrophobic. Besides, the modified nanoparticles can effectively inhibit the formation of coffee rings during evaporation. These results may have important applications for the energy-efficient enhancement of the water evaporation rate.

Thermal Stability, Pyrolysis Behavior, and Fire-Retardant Performance of Melamine Cyanurate@Poly(cyclotriphosphazene-co-4,4'-sulfonyl diphenol) Hybrid Nanosheet-Containing Polyamide 6 Composites

A novel halogen-free highly cross-linked supramolecular poly(cyclotriphosphazene-co-4,4'-sulfonyl diphenol) (PZS)-functionalized melamine cyanurate (MCA) (MCA@PZS) hybrid nanosheet fire-retardant (FR) was synthesized and thoroughly characterized using scanning electron microscopy, Fourier-transform infrared (FTIR), X-ray diffraction, and X-ray photoelectron spectroscopy analyses. The polyamide 6 (PA6) composites comprising MCA, PZS, and the MCA@PZS hybrids were prepared via the melt-blending technique. The thermogravimetric analysis combined with FTIR and mass spectroscopy revealed that during thermal degradation, the PA6/MCA@PZS composites released less toxic gases and small organic volatile compounds than the neat PA6 and composites containing MCA or PZS solely. Moreover, compared to neat PA6, the PA6 composite with a 5 wt % MCA@PZS hybrid exhibited enhanced fire retardation properties, with a 29.4 and 32.1% decrease in the peak heat and total heat release rates, respectively. Besides, the PA6 composites with MCA@PZS-5% content achieved a V-0 rating in the UL-94 test. Finally, based on the obtained results from gaseous and condensed phases, the possible mechanism responsible for improved FR properties of the PA6/MCA@PZS composites was proposed.

Thin cyclomatrix polyphosphazene films: interfacial polymerization of hexachlorocyclotriphosphazene with aromatic biphenols

Cyclomatrix polyphosphazene films have been synthesized by interfacial polymerization of hexachlorocyclotriphosphazene with a variety of biphenols.

Flame retarding epoxy composites with poly(phosphazene-co-bisphenol A)-coated boron nitride to improve thermal conductivity and thermal stability

A novel poly(cyclotriphosphazene-co-bisphenol A)-coated boron nitride (PCB-BN) was synthesized by in situ polymerization on the surface of BN. The epoxy/PCB-BN composites showed the enhanced thermal conductivity with the improved flame retardance.

Borazine-based inorganic–organic hybrid cyclomatrix microspheres by silicon/boron exchange precipitation polycondensation

Borazine-based inorganic–organic hybrid cyclomatrix microspheres with a mean diameter of about 900 nm have been obtained via a novel silicon/boron exchange precipitation polycondensation approach.

Liquid Marbles Stabilized by Fluorine-Bearing Cyclomatrix Polyphosphazene Particles and Their Application as High-Efficiency Miniature Reactors

Increasing attention has been paid to fabricate multifunctional stabilizers of liquid marbles for expanding their application. Here, a kind of hydrophobic cyclomatrix polyphosphazene particles (PZAF) were facilely prepared using a one-step precipitation polycondensation of hexachlorocyclotriphosphazene and 4,4'-(hexafluoroisopropylidene)diphenol, and their ability to stabilize liquid marbles was first investigated. The Ag nanoparticle-decorated PZAF particles (Ag/PZAF) were then fabricated by an in situ reduction of silver nitrate onto PZAF particles and used to construct catalytic liquid marbles. The results revealed that the reduction of methylene blue (MB) in aqueous solution by sodium borohydride could be highly efficiently catalyzed in the catalytic liquid marbles, even with a large volume. An excellent cycle use performance of the catalytic liquid marbles without losing catalytic efficiency was also present. The high catalytic activity is mainly attributed to the uniform immobilization of Ag nanoparticles onto PZAF particles and the adsorption behavior of PZAF particles toward MB, which may play an effect on allowing high catalytic surface area and effective accelerating the mass transfer of MB to the Ag catalytic active sites, respectively. Therefore, the combination of Ag nanoparticles with PZAF particles has been demonstrated clearly to be a facile and effective strategy to obtain the functional stabilizer for preparing the catalytic liquid marbles as promising miniature reactors used in heterogeneous catalytic reactions.

A facile synthesis, structural morphology and fluorescent properties of cross-linked poly(cyclotriphosphazene-co-1,3,5-tri(4-hydroxyphenyl)benzene) hybrid copolymer microspheres

Tunable size synthesis of fluorescent active microspheres with proposed unique chemical structure.

A strategy for the synthesis of cyclomatrix-polyphosphazene nanoparticles from non-aromatic monomers

Cyclomatrix-polyphosphazenes (C-PPZs) are a new class of nanomaterials that have attracted significant interest owing to their unique inorganic–organic hybrid structure and tunable properties.

Water-triggered self-assembly polycondensation for the one-pot synthesis of cyclomatrix polyphosphazene nanoparticles from amino acid ester

Water-triggered self-assembly polycondensation was proposed for preparation of cyclomatrix polyphosphazene nanoparticles from amino acid ester, and a critical solubility parameter was found to determine whether the nanoparticles were formed.

One-step preparation of fluorescent inorganic–organic hybrid material used for explosive sensing

As a fluorescent inorganic–organic hybrid polymer, TPE-CP is prepared through one-step polycondensation and used for explosive sensing.

Fabrication and superhydrophobic behavior of fluorinated microspheres

We describe the preparation of fluorinated microspheres by precipitation polymerization and their use to fabricate superhydrophobic surfaces. For that purpose, two different approaches have been employed. In the first approach, a fluorinated monomer (either 4-fluorostyrene or 2,3,4,5,6-pentafluorostyrene) was added to the initial mixture of monomers constituted by styrene (S) and divinylbenzene (DVB). The second approach is based on the encapsulation of a block copolymer, polystyrene-b-poly(2,3,4,5,6-pentafluorostyrene), during the polymerization of the monomers (S and DVB), thus enabling the formation of particles with perfluorinated chains instead of single functional groups at the interface. Both approaches led to narrow polydisperse particles with fluoro-functional groups at the interface as demonstrated by scanning electron microscopy (SEM), infrared (IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Surface array of particles obtained by simple solvent casting presented superhydrophobic behavior with contact angles of water droplets of ca. 160-165°.