Stable Synthetic Bacteriochlorins for Photodynamic Therapy: Role of Dicyano Peripheral Groups,Central Metal Substitution (2H,Zn, Pd), and Cremophor EL Delivery

A series of four stable synthetic bacteriochlorins was tested in vitro in HeLa cells for their potential in photodynamic therapy (PDT). The parent bacteriochlorin (BC), dicyano derivative (NC)₂BC and corresponding zinc chelate (NC)₂BC–Zn and palladium chelate (NC)₂BC–Pd were studied. Direct dilution of a solution of bacteriochlorin in an organic solvent (N,N‐dimethylacetamide) into serum‐containing medium was compared with the dilution of bacteriochlorin in Cremophor EL (CrEL; polyoxyethylene glycerol triricinoleate) micelles into the same medium. CrEL generally reduced aggregation (as indicated by absorption and fluorescence) and increased activity up to tenfold (depending on bacteriochlorin), although it decreased cellular uptake. The order of PDT activity against HeLa human cancer cells after 24 h incubation and illumination with 10 J cm^?2 of near‐infrared (NIR) light is (NC)₂BC–Pd (LD₅₀=25 nM ) > (NC)₂BC > (NC)₂BC–Zn ≈ BC. Subcellular localization was determined to be in the endoplasmic reticulum, mitochondria and lysosomes, depending on the bacteriochlorin. (NC)₂BC–Pd showed PDT‐mediated damage to mitochondria and lysosomes, and the greatest production of hydroxyl radicals as determined using a hydroxyphenylfluorescein probe. The incorporation of cyano substituents provides an excellent motif for the enhancement of the photoactivity and photostability of bacteriochlorins as PDT photosensitizers.     

Biodistribution and photodynamic efficacy of a water-soluble, stable, halogenated bacteriochlorin against melanoma

The in vitro phototoxicity of a photostable, synthetic, water‐soluble, halogenated bacteriochlorin, 5,10,15,20‐tetrakis(2‐chloro‐5‐sulfophenyl)bacteriochlorin (TCPBSO₃H), toward mouse melanoma (S91) cells is ～60‐fold higher than that of the analogous porphyrin, and is associated with very weak toxicity in the dark; 90 % of S91 cells were killed in response to a light dose of 0.26 J cm^?2 in the presence of [TCPBSO₃H]=5 μM . In vivo toxicity toward DBA mice is very low, even at doses of 20 mg kg^?1. In vivo pharmacokinetics and biodistribution of TCPBSO₃H were studied in DBA mice with S91 tumors; 24 h after intraperitoneal injection of 10 mg kg^?1, TCPBSO₃H demonstrated preferential accumulation in S91 mouse melanoma, with tumor‐to‐normal tissue ratios of 3 and 5 for muscle and skin, respectively. Photodynamic therapy (PDT) performed under these conditions, with 90 mW cm^?2 diode laser irradiation at λ 750 nm for 20 min (total light dose of 108 J cm^?2), resulted in tumor regression. Tumor recurrence was observed only approximately two months after treatment, confirming the efficacy of this PDT against melanoma.     

New Halogenated Water‐Soluble Chlorin and Bacteriochlorin as Photostable PDT Sensitizers: Synthesis,Spectroscopy, Photophysics,and in vitro Photosensitizing Efficacy

Chlorin and bacteriochlorin derivatives of 5,10,15,20‐tetrakis(2‐chloro‐5‐sulfophenyl)porphyrin have intense absorptions in the phototherapeutic window, high water solubility, high photostability, low fluorescence quantum yield, long triplet lifetimes, and high singlet oxygen quantum yields. Biological studies revealed their negligible dark cytotoxicity, yet significant photodynamic effect against A549 (human lung adenocarcinoma), MCF7 (human breast carcinoma) and SK‐MEL‐188 (human melanoma) cell lines upon red light irradiation (cutoff λ<600 nm) at low light doses. Time‐dependent cellular accumulation of the chlorinated sulfonated chlorin reached a plateau at 2 h, as previously observed for the related porphyrin. However, the optimal incubation time for the bacteriochlorin derivative was significantly longer (12 h). The spectroscopic, photophysical, and biological properties of the compounds are discussed in relevance to their PDT activity, leading to the conclusion that the bacteriochlorin derivative is a promising candidate for future in vivo experiments.     

Intravenous Single-Dose Toxicity of Redaporfin-Based Photodynamic Therapy in Rodents

We assessed the tolerability and safety in rodents of a single intravenous (i.v.) dose of redaporfin, a novel photosensitizer for Photodynamic Therapy (PDT) of cancer. Two approaches were used to evaluate acute toxicity: (i) a dose escalation study in BALB/c mice to evaluate the maximum tolerated dose of redaporfin; and (ii) a safety toxicology study in Wistar rats, of a single dose of redaporfin, with or without illumination, to evaluate possible signs of systemic toxicity. Redaporfin formulation was well tolerated by mice, with no signs of adverse reactions up to 75 mg/kg. In rats, there were no relevant changes, except for a significant, but transient, increase in the blood serum markers for hepatic function and muscle integrity, and also on neutrophil counts, observed after the application of light. The overall results showed that redaporfin-PDT is very well tolerated. No abnormalities were observed, including reactions at the injection site or skin phototoxicity, although the animals were maintained in normal indoor lighting. Redaporfin also showed a high efficacy in the treatment of male BALB/c mice with subcutaneously implanted colon (CT26) tumours. Vascular-PDT with 1.5 mg/kg redaporfin and a light dose of 74 J/cm² led to the complete tumour regression in 83% of the mice.     

Development of an Environmentally Acceptable Detergent Formulation for Fatty Soils Based on the Lipase from the Indigenous Extremophile Pseudomonas aeruginosa Strain

A lipase derived from an indigenous extremophile Pseudomonas aeruginosa strain isolated from rancid metalworking fluid was evaluated as a detergent additive. Applicability of the obtained enzyme as an additive in detergent formulations was confirmed by its implementation in the formulations of several new products differing in surfactant type and concentrations, demonstrating satisfactory performance in terms of degreasing efficiency and composition of the washing wastewater. The degreasing efficiency of different enzyme‐containing detergent formulations was studied on cotton fabric samples stained with triolein and compared to that of formulations containing only surfactant. The highest efficiency of the fatty soil removal in formulations with a low content of surfactants (0.4 %) was noted in the enzyme formulation containing Lutensol^® XP‐80 (degreasing efficiency >80 %) and Triton^® X‐100 (degreasing efficiency >60 %). An attempt was then made to optimize the composition of the enzyme formulation on the basis of one or both of these surfactants using statistically planned experiments and response surface methodology (RSM). Taking into consideration the environmental aspects and the shown detergency, it appeared that rather high degreasing effects were achieved in formulations based on a low quantities of Lutensol^® XP‐80 (0.4 %) at all pH values. However, pH seemed to have a notable effect since the degreasing efficiency significantly increased with increasing pH and the amount of the enzyme. Formulations having a moderate alkaline pH profile and higher amount of enzyme exhibited a high cleaning performance of fatty soil even at a low concentration of the surfactant.     

Comparison of in Silico,Electrochemical, in Vitro and in Vivo Metabolism of a Homologous Series of (Radio)fluorinated σ1 Receptor Ligands Designed for Positron Emission Tomography

The imaging of σ₁ receptors in the brain by fluorinated radiotracers will be used for the validation of σ₁ receptors as drug targets as well as for differential diagnosis of diseases in the central nervous system. The biotransformation of four homologous fluorinated PET tracers 1′‐benzyl‐3‐(ω‐fluoromethyl to ω‐fluorobutyl)‐3H‐spiro[2]benzofuran‐1,4′‐piperidine] ([¹⁸F] 1 – 4 ) was investigated. In silico studies using fast metabolizer (FAME) software, electrochemical oxidations, in vitro studies with rat liver microsomes, and in vivo metabolism studies after application of the PET tracers [¹⁸F] 1 – 4 to mice were performed. Combined liquid chromatography and mass spectrometry (HPLC–MS) analysis allowed structural identification of non‐radioactive metabolites. Radio‐HPLC and radio‐TLC provided information about the presence of unchanged parent radiotracers and their radiometabolites. Radiometabolites were not found in the brain after application of [¹⁸F] 2 – 4 , but liver, plasma, and urine samples contained several radiometabolites. Less than 2 % of the injected dose of [¹⁸F] 4 reached the brain, rendering [¹⁸F] 4 less appropriate as a PET tracer than [¹⁸F] 2 and [¹⁸F] 3 . Compounds [¹⁸F] 2 and [¹⁸F] 3 possess the most promising properties for imaging of σ₁ receptors in the brain. High σ₁ affinity (K_i=0.59 nm ), low lipophilicity (logD_7.4=2.57), high brain penetration (4.6 % of injected dose after 30 min), and the absence of radiometabolites in the brain favor the fluoroethyl derivative [¹⁸F] 2 slightly over the fluoropropyl derivative [¹⁸F] 3 for human use.     

Cone calorimeter evaluation of two flame retardant cotton fabrics

Unbleached (gray) cotton needle‐punched nonwoven (NW) fabrics with 12.5% polypropylene scrim were treated with two phosphate–nitrogen‐based flame retardant (FR) formulations, Southern Regional Research Center (SRRC)‐1 and SRRC‐2. The SRRC‐1 formulation contains diammonium phosphate as the FR chemical along with urea and dimethyloldihydroxyethyleneurea. Because a trace amount of formaldehyde was still expected to be released from SRRC‐1‐treated FR cotton under high heat, it was preferable to eliminate the dimethyloldihydroxyethyleneurea, leading to the revised formulation SRRC‐2. It has a higher content of diammonium phosphate and did not use the polyethylene emulsion that was in SRRC‐1. Both formulations were of low cost as they were developed at SRRC using industrial grade chemicals. The fabrics were evaluated with a cone calorimeter using three heat flux levels, 20, 30, and 50 kW/m². On the basis of the overall cone calorimeter results for heat released and ignition times, FR NW fabrics that were treated with SRRC‐2 were found to be slightly superior in flammability properties to those treated with the earlier SRRC‐1 formulation, but the differences were statistically insignificant. Both preparations were much less flammable than the untreated control cotton NW fabrics. Compared with the untreated NW fabrics, the FR fabrics had higher visible smoke production. Copyright © 2012 John Wiley & Sons, Ltd.     

Proliposomes of lisinopril dihydrate for transdermal delivery: Formulation aspects and evaluation

We formulated and evaluated proliposomal gel of relatively low bioavailable drug lisinopril dihydrate (LDH) for transdermal delivery. Several proliposomal gel formulations of lisinopril dihydrate were prepared by modified coacervation phase separation method and examined for formation of liposomes by optical microscope and characterized by transmission electron microscopy. The formulations were evaluated for size, zeta potential, entrapment efficiency, rheological behavior, ex vivo drug permeation, skin irritation and stability. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) studies were performed to understand the phase transition behavior and mechanism for skin permeation, respectively. The microscopic examination revealed the formation of liposomes from proliposomal gel, and the size of the vesicles was found to be in the range of 385 nm to 635 nm. Entrapment efficiency was high for the formulation containing greater amounts of phosphatidylcholine. The DSC studies indicated the amorphous form of LDH in proliposomal gel formulation. Ex vivo permeation studies revealed sustained permeation of drug from proliposomal gels studied. The stability studies reveal that the proliposomal formulations are more stable when stored at refrigeration temperature (4 °C). In conclusion, proliposomal gels offer potential and prove to be efficient carriers for improved and sustained transdermal delivery of lisinopril dihydrate.     

Synthesis and properties of fluorinated biphenyl‐type epoxy resin

A novel fluorinated biphenyl‐type epoxy resin (FBE) was synthesized by epoxidation of a fluorinated biphenyl‐type phenolic resin, which was prepared by the condensation of 3‐trifluoromethylphenol and 4,4′‐bismethoxymethylbiphenyl catalyzed in the presence of strong Lewis acid. Resin blends mixed by FBE with phenolic resin as curing agent showed low melt viscosity (1.3–2.5 Pa s) at 120–122°C. Experimental results indicated that the cured fluorinated epoxy resins possess good thermal stability with 5% weight loss under 409–415°C, high glass‐transition temperature of 139–151°C (determined by dynamic mechanical analysis), and outstanding mechanical properties with flexural strength of 117–121 MPa as well as tensile strength of 71–72 MPa. The thermally cured fluorinated biphenyl‐type epoxy resin also showed good electrical insulation properties with volume resistivity of 0.5–0.8 × 10¹⁷ Ω cm and surface resistivity of 0.8–4.6 × 10¹⁶ Ω. The measured dielectric constants at 1 MHz were in the range of 3.8–4.1 and the measured dielectric dissipation factors (tan δ) were in the range of 3.6–3.8 × 10^?3. It was found that the fluorinated epoxy resins have improved dielectric properties, lower moisture adsorption, as well as better flame‐retardant properties compared with the corresponding commercial biphenyl‐type epoxy resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,Surface Activity,and Antimicrobial Efficacy of Diaryliodonium Salt‐Derived Amphiphiles

Two sets of 19 amphiphiles derived from diaryliodonium salt in the form of 4‐methylbenzenesulfonate salts and trifluoromethanesulfonate salts were synthesized in good yields through the oxidation of 17 different aryl iodides using oxone (potassium peroxymonosulfate) as the oxidation agent in Route I and meta‐chloroperoxybenzoic acid as the oxidation agent in Routes II and III, followed by Friedel–Crafts reaction with (2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)benzene to obtain the target compounds ( 1 – 19 ). Their structures were characterized by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and high‐resolution mass spectrometry studies. Their surface activities were evaluated on the basis of surface tension and critical micelle concentration measurements by the Wilhelmy plate method at 25 °C. With their good water solubility, diaryliodonium salts ( 1 – 19 ) have excellent short‐term bactericidal efficacy against Bacillus cereus in the concentration of 600 ppm at 20 °C. After compounding 1 or 18 with the broad‐spectrum but skin‐irritating antibacterial agent Kathon CG (methylchloroisothiazolinone in combination with methylisothiazolinone) in the ratio of 1:1 by mass, both formulations maintained lethality rate of >90% after 48 h.     

New insights into the degradation mechanism of poly (vinyl chloride), Part (III): Implementation of new costabilizers—Towards heavy metal free systems (HMFS)

To replace zinc in PVC stabilized formulations and generate a Heavy Metal Free System (HMFS), different costabilizers (i.e., 6‐amino‐1,3 dimethyluracil (Uracil), sodium tetraborate (Borax), sodium phenyl phosphinate (SPP), and NPPD (N‐phenyl‐3‐acetylpyrrolidin‐2,4‐dione), and their combinations) were tested. HCl evolution showed the outstanding performance of SPP, which was overshadowed by its poor color stability. To optimize the levels of costabilizers in the formulation, experimental design was applied to two different formulations. For a formulation containing Uracil + SPP + NPPD, the induction time (Ti) could reach up to 50 min. Moreover, an induction time of more than 80 min could be obtained with the combination of the costabilizers Borax + SPP + NPPD. The dynamic stability in terms of color measurements showed that excellent color control was achieved by the addition of 2phr of Borax into the formulation, with even better results than the mixture of the three costabilizers at their highest levels (Borax + SPP + NPPD). For a formulation containing Uracil + SPP + NPPD, the best results were again obtained by the combination of the highest levels of the three costabilizers. The mechanistic action of SPP with a model compound (4C2H) was studied by ¹H and ³¹P‐FTnmr. The reaction was obscured by the fact that SPP underwent hydrolysis in aqueous conditions. However, the color measurements showed that because the initial color was poor, it is unlikely that SPP is acting as a peroxide decomposer in the conventional sense. In addition, the great extension in the Ti means that SPP must be inhibiting chain propagation and it may do this by stabilizing the carbocation generated during the dehydrochlorination process, along with its acid scavenging activity. Thus, when the costabilizer is totally consumed, the rate of free HCl evolution is very high, as the results confirm. The fact that phenyl phosphinic acid (PPA), the acid form, did not stabilize PVC seems to be in agreement with the above reasoning. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 122–143, 2005     

Lipid Oxidation and Degradation Products in Raw Materials: Low‐Fat Topical Skin‐Care Formulations

Topical skin formulations with a lipid content below 15% were stored for 6 months at 5, 20, or 40 °C or for 2 weeks at 50 °C in darkness or at 20 °C with exposure to light for 6 months. The volatile lipid‐oxidation compounds formed during this storage period were compared to those formed in the raw materials during 3 months of accelerated stability storage at 40 °C. The volatile compounds were collected by dynamic headspace and analyzed using gas chromatography–mass spectrometry. It was possible to link eight out of nine volatile compounds detected during storage of topical skin formulations to the raw materials. In addition, a possible link between the appearance of butane nitrile and the decomposition of an initiator used for polyacrylate crosspolymer‐6 production was observed. The polymer may originate from texture modifiers added to the topical skin formulation or from plastics used for packaging of topical skin formulations. Furthermore, six well‐known lipid‐oxidation and nonenzymatic browning products were suggested to originate from the two raw materials, tricaprylin/tricaprin and coconut oil.     

Nanosuspension delivery of paclitaxel to xenograft mice can alter drug disposition and anti-tumor activity

Paclitaxel is a common chemotherapeutic agent that is effective against various cancers. The poor aqueous solubility of paclitaxel necessitates a large percentage of Cremophor EL:ethanol (USP) in its commercial formulation which leads to hypersensitivity reactions in patients. We evaluate the use of a crystalline nanosuspension versus the USP formulation to deliver paclitaxel to tumor-bearing xenograft mice. Anti-tumor efficacy was assessed following intravenous administration of three 20 mg/kg doses of paclitaxel. Paclitaxel pharmacokinetics and tissue distribution were evaluated, and differences were observed between the two formulations. Plasma clearance and tissue to plasma ratio of mice that were dosed with the nanosuspension are approximately 33- and 11-fold higher compared to those of mice that were given the USP formulation. Despite a higher tumor to plasma ratio for the nanosuspension treatment group, absolute paclitaxel tumor exposure was higher for the USP group. Accordingly, a higher anti-tumor effect was observed in the xenograft mice that were dosed with the USP formulation (90% versus 42% tumor growth inhibition). This reduction in activity of nanoparticle formulation appeared to result from a slower than anticipated dissolution in vivo. This study illustrates a need for careful consideration of both dose and systemic solubility prior utilizing nanosuspension as a mode of intravenous delivery.     

Electrospinning of Fluorinated Polymers: Formation of Superhydrophobic Surfaces

Summary: Superhydrophobic surfaces are generated by a simple one‐step method of electrospinning of fluorinated homopolymers and copolymers of PFS. The hydrophobicity and superhydrophobicity can be changed by simply changing the surface morphology, which is possible by changing the electrospinning conditions. The appropriate combination of surface morphology and fluorinated materials led to the formation of super‐water‐resistant coatings showing the ‘water‐roll’ effect at an angle of 0°, i.e. placement of water droplets on such surfaces was not possible as they immediately rolled away. The effect is compared with the corresponding nonfluorinated PS and found to be clearly distinct in terms of water‐roll effect. Incorporation of about 30 mol‐% PFS onto the PS backbone could also convert hydrophobic PS surfaces to superhydrophobic surfaces. The effect is generalized by also using a new fluorinated poly(p‐xylylene) derivative. The molecular weight of the polymers has no noticeable effect on hydrophobicity/superhydrophobicity behavior.

SEM micrographs PFS–styrene copolymer, 10% solution in THF:DMF (1:1 v/v); 5% solution in THF:DMF (1:1 v/v) and homo‐PPFS < 2% solution in THF:DMF (1:1 v/v).     

Tissue uptake study and photodynamic therapy of melanoma-bearing mice with a nontoxic, effective chlorin

Chlorins have intense red absorptions and high tumor affinities that make them interesting candidates for photodynamic therapy (PDT) of cancer. This paper reports cytotoxicity, phototoxicity, in vitro cellular uptake, and in vivo biodistribution and PDT efficacy of a synthetic chlorin derivative (TCPCSO₃H) towards Cloudman melanoma cells (S91). No cytotoxic effects were observed in vitro at concentrations up to 20 μm, and no toxicity was observed in vivo in DBA mice with doses up to 2 mg kg^?1. Pharmacokinetics and biodistribution of TCPCSO₃H were evaluated in vivo in DBA mice bearing S91 tumors. TCPCSO₃H demonstrated preferential accumulation in S91 mouse melanoma, with tumor‐to‐normal tissue ratios of 5 and 11 for muscle and skin, respectively, 24 h after intravenous injection of 2 mg kg^?1. Photodynamic therapy performed under these conditions with 70 mW cm^?2 diode laser irradiation at 655 nm for 25 min (total light dose=105 J cm^?2) resulted in scab formation, followed by temporary or permanent (>60 days) tumor remission. According to the Kaplan–Meier analysis, the median survival time of the control group was 9 days, whereas that of the treated group was 38 days.     

Direct fluorination of the polyimide matrimid® 5218: The formation kinetics and physicochemical properties of the fluorinated layers

Fluorinated polymers have a set of unique properties, including improved chemical stability and thermal stability and good barrier and membrane parameters, which are mainly defined by their surface properties. This article presents systematic data on the direct fluorination of the polyimide Matrimid® 5218, a commercially available polymer suitable for the formation of gas‐separation hollow fibers. Changing the fluorination conditions (i.e., the fluorinated mixture composition, fluorine partial pressure, and treatment duration) allows the rate of formation of the surface‐fluorinated layer over the 0.1–10 μm range to be kept under control. The physicochemical properties of modified layers (i.e., the chemical composition, formation of radicals, refractive index, IR and UV spectra, density, and surface energy) are examined. The thickness of the fluorinated layer (δ_F) depends on the fluorination duration (t): δ_F ～ t^0.5. During fluorination, hydrogen atoms are replaced with fluorine, double bonds are saturated with fluorine, and at least one CN bond in the five‐member ring is disrupted. Fluorination results in a significant increase in the polymer density, transparency in the visible and ultraviolet regions of spectra, and a reduction of the refractive index. A high concentration of long‐living radicals (up to ～5 × 10¹⁹ radicals/cm³ of the fluorinated layer) is generated under fluorination. This can be used for subsequent grafting (e.g., with acrylonitrile). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 6–17, 2004     

Effects of the Tumor‐Vasculature‐Disrupting Agent Verubulin and Two Heteroaryl Analogues on Cancer Cells,Endothelial Cells,and Blood Vessels

Two analogues of the discontinued tumor vascular‐disrupting agent verubulin (Azixa®, MPC‐6827, 1 ) featuring benzo‐1,4‐dioxan‐6‐yl (compound 5 a ) and N‐methylindol‐5‐yl (compound 10 ) residues instead of the para‐anisyl group on the 4‐(methylamino)‐2‐methylquinazoline pharmacophore, were prepared and found to exceed the antitumor efficacy of the lead compound. They were antiproliferative with single‐digit nanomolar IC₅₀ values against a panel of nine tumor cell lines, while not affecting nonmalignant fibroblasts. Indole 10 surpassed verubulin in seven tumor cell lines including colon, breast, ovarian, and germ cell cancer cell lines. In line with docking studies indicating that compound 10 may bind the colchicine binding site of tubulin more tightly (E_bind=?9.8 kcal mol^?1) than verubulin (E_bind=?8.3 kcal mol^?1), 10 suppressed the formation of vessel‐like tubes in endothelial cells and destroyed the blood vessels in the chorioallantoic membrane of fertilized chicken eggs at nanomolar concentrations. When applied to nude mice bearing a highly vascularized 1411HP germ cell xenograft tumor, compound 10 displayed pronounced vascular‐disrupting effects that led to hemorrhages and extensive central necrosis in the tumor.     

Cross‐Linked Fluorinated Poly(Aryl Ether) (C‐FPAE) Films: Preparation Strategy,Performance Study,and Low Dielectric Applications

The production of low dielectric materials that can be used in high temperature environments is the primary aim of this work. A cross‐linked structure is introduced into fluorinated poly(aryl ether) (named as FPAE) with high molecular weight (M_w, 140 000 g mol^?1) and linear molecular structure using nucleophilic substitution reaction at the ortho‐position of decafluorobiphenyl monomer units in the FPAE molecular chain. The curing temperature and curing time are optimized and the final conditions for the cross‐linking reaction in this study are determined to be 300 °C for 1 h. Moreover, the dielectric constant and dielectric loss of the C‐FPAE film respectively are 2.67 and 0.006 at 1000 Hz when 1 wt% of crosslinking agent is added, and the cross‐linked fluorinated poly(aryl ether) film shows excellent thermal stability (T_d(5%), 495 °C), dimensional stability, hydrophobic properties, and high storage modulus in high temperature environments. Such novel low dielectric material with excellent performances has important application value in the aerospace and the integrated electronics field.     

An Analytically Defined Fire‐Suppressing Foam Formulation for Evaluation of Fluorosurfactant Replacement

A 4‐component, analytically defined, reference fluorosurfactant formulation (Ref‐aqueous film forming foam [AFFF]) composed of 0.3% fluorocarbon‐surfactant concentrate (Capstone 1157), 0.2% hydrocarbon‐surfactant concentrate (Glucopon 215 UP), and 0.5% diethylene glycol mono butyl ether by volume in distilled water was found to have rapid fire extinction comparable to a commercial AFFF in tests conducted on a bench scale and a large scale (28 ft², part of US Military Specification, MIL‐F‐24385F). The Ref‐AFFF was analytically characterized to provide the identity and quantity of the chemical structures of the surfactant molecules that were lacking for commercial AFFF formulations. To arrive at an acceptable Ref‐AFFF formulation, 3 candidate formulations containing different hydrocarbon surfactants in varying amounts were evaluated and ranked relative to a commercial AFFF using a bench‐scale fire‐extinction apparatus; varying the hydrocarbon surfactant was found to affect the fire‐extinction time. The ranking was confirmed by the large‐scale tests suggesting that the bench‐scale apparatus is a reasonable research tool for identifying surfactants likely to succeed in the large‐scale test. In the future, replacing the fluorocarbon surfactant with an alternative surfactant in the Ref‐AFFF enables a direct comparison of fire extinction and environmental impact to identify an acceptable fluorine‐free formulation.