Benzenediazonium Salt Research Articles

Rice husk ash reinforced natural rubber composites: effect of benzene diazonium salt treatment.

Rice husks are a major agricultural residue with growing volume in Nigeria in recent times owing to the country’s drive for self-sufficiency in rice production. Rice husks have great potential for use as fillers in biocomposites for applications in the manufacture of engineering products. However, the hydrophilic nature of this agricultural residue limits its choice as fillers in biocomposites. This study focused on the modification of the hydrophilic property of rice husks through treatment with benzene diazonium salts in different media (pH levels of 7, 9, 10.5 and 12) to attain the most suitable treatment media for processing rice husks. The treated samples were burned in a furnace at a temperature of 600oC for 6 hours. The compounding of the rice husk ash, CV-60 natural rubber and additives were done on a two-roll mill at a speed ratio of 1:1.25 with rollers temperature of 70oC and cured in a hydraulic press at 130oC for 20 minutes at 2.5 MPa. The composites were developed using rice husk ash as the filler with loadings of 30, 34, 38, 42, 46 and 50 phr. Characterizations and tests carried out include Fourier transform infrared spectroscopy (FTIRS), X-ray fluorescence (XRF), shore A hardness, compressive strength and tensile strength. The composites developed using pH 10.5 treated rice husks yielded the highest silica content and showed better adhesion characteristics. The sample with 42 phr loading gave better mechanical properties with tensile strength, compressive strength, and tensile modulus of 18.5 MPa, 39.72 MPa and 7.87 MPa respectively with a corresponding shore A hardness of 45.32. The rice husk ash filled natural rubber composites can find application in the development of vibration isolation mounts.

Novel covalent immobilization of cobalt (II) octa acyl chloride phthalocyanines onto phenylethylamine pre-grafted gold via spontaneous amidation

In this work, a gold electrode surface was pre-grafted with phenylethylamine (PEA) thin film for spontaneous covalent immobilization of cobalt (II) octa acyl chloride (CoOAClPc) via the nucleophilic addition reaction. Pre-grafting of PEA thin film was achieved by electrochemical reduction of 4-(2-aminoethyl) benzene diazonium (AEBD) salt. Cobalt (II) octa acyl chloride phthalocyanine (CoOAClPc) was successfully synthesized and covalently immobilized onto the pre-grafted gold electrode surface to form a thin monolayer of Au-PEA-CoOAClPc. Upon hydrolysis of the thin monolayer, the –COCl terminal functional groups were converted to -COOH to form Au-PEA-CoOCAPc. The presence of PEA and PEA-CoOCAPc was confirmed by electrochemical X-ray photoelectron spectroscopy surface characterization. The pH sensitivity of -COOH terminal groups was studied using a negatively charged [Fe(CN)6]3−/4− and a positively charged [Ru(NH3)6]2+/3+ redox probes. The Au-PEA-CoOCAPc was investigated for electrocatalytic and electroanalytical properties towards the detection of catecholamine neurotransmitters (dopamine, epinephrine, and norepinephrine). The electrocatalytic oxidation of the catecholamine neurotransmitters in PBS solution (pH 7.4) was studied using differential pulse voltammetry (DPV) in a linear range up to 50 μM. The limit of detection (LOD) was determined to be 64 nM, 0.22 μM and 0.17 μM for dopamine (DA), epinephrine (EP) and norepinephrine (NOR) respectively. The limit of quantification (LOQ) was determined to be 0.21 μM, 0.73 μM and 0.56 μM for DA, EP and NOR respectively. Stable and reproducible novel method of electrode fabrication to form Au-PEA-CoOCAPc was achieved. Excellent analytical properties (sensitivity, low detection limits and limit of quantification) were obtained by using the fabricated electrochemical sensors, Au-PEA-CoOCAPc, for the determination of catecholamine neurotransmitters and screening of ascorbic acid (AA).

One-step spontaneous grafting via diazonium chemistry for the fabrication of robust bionic multifunctional superhydrophobic fabric

Abstract A superhydrophobic cotton fabric with peanut leaf-like nanoplates, 3D flower-like and mulberry-like microstructure surface with varied water adhesion was fabricated via simple one-step spontaneous grafting method at room temperature. The spontaneous covalent grafting of 3,5-di(trifluoromethyl)phenyl functionalities to cotton fibers by the Fe0 reduction of the corresponding 3,5-di(trifluoromethyl)benzene diazonium salt has been studied in aqueous acid, which relates to the homolytic reduction of diazonium salts to produce radicals followed by grafting to the cotton fibers. We adjust the spontaneous grafting process by simply changing the molarity of HCl solutions to control the micro-nanostructures of β-FeOOH on the cotton fabric surfaces. Thus, the superhydrophobic surface adhesion forces to the water droplets can be effectively adjusted from 21.36 μN (lowest) to 159.35 μN (highest) via changing the surface architecture. The modified cotton fabric surface exhibited excellent superhydrophobicity with a water contact angle (WCA) of 167.2 ± 1.6°, sliding angle (WSA) of 1.8 ± 0.3° and superoleophilicity with the n-hexane contact angle (OCA) of 0°. Thus, the superhydrophobic cotton fabric can be used for self-cleaning and oil/water separation with an efficiency of as high as 98.9%, which has good recyclability, laundering and abrasion durability. Moreover, the movement of the superhydrophobic cotton fabric in water can be controlled by the orientation of a magnet without contact. Meanwhile, the micro-nanostructured rough surface with tunable adhesive force to water can be used to detect AgNO3 or NaOH in the aqueous solution, and so other potential applications in the droplet based microreactor can be found.

Investigation of the Physico-Chemical Absorption Characterizations of Jute Polymer Clay Nanocomposites as a Function of Chemical Treatments

In this study, jute polyethylene clay nanocomposites were developed using hot press technique. The hydrophilic nature of fiber and nanoclay exhibited poor interfacial interaction to hydrophobic polymer matrix. In order to enhance the interfacial interaction among fiber, polymer, and nanofillers, the chemically treated jute (with benzenediazonium salt, propionic anhydride, and 3-isocyanatopropyltriethoxy silane) and organically modified nanoclay were used for the manufacturing of nanocomposites in this study. The effect of chemical treatments and nanoclay addition on the improvement of absorption characterizations of prepared nanocomposites against water and few chemical reagents have been investigated. It has been observed that the treated jute composites showed higher improvement in absorption properties than raw jute composite and silane treated jute composite found highest value. In addition, nanoclay filled composites showed higher improvement than composite without nanoclay and MMT-1.31PS nanoclay loaded nanocomposite exhibited highest improvement among five types of MMT nanoclay used in this work. The fabricated nanocomposites were resistant to all chemicals used except carbon tetrachloride.

Potent application of jute polyethylene composites for storage tank as a function of fiber treatment

The jute polyethylene nanocomposites were manufactured using the hot-press technique with different fiber weight fractions. The hydrophilic nature of fiber exhibited poor interfacial interaction to hydrophobic polymer matrix. Three types of chemical reagents such as: benzenediazonium salt (BDS), propionic anhydride (PA), and 3-isocyanatopropyl triethoxysilane (Silane) have been used to reduce hydrophilicity of jute fibers. The chemical resistance tests of prepared composites were performed in order to observe whether these composites are resistant to various chemicals such as: acids, alkalis, and solvents. It was observed that the fabricated composites were resistant to all chemicals except carbon tetrachloride. The treated jute composites showed higher chemical resistance than raw jute composite and silane treated jute composite gave the highest resistance which can be suggested for making the water and chemical storage tanks.

The Effect of Fiber Chemical Treatment on Chemical Resistance Behavior of Jute Polyethylene Composites for Storage Tank Application

The jute polyethylene composites were developed using the hot-press technique with different fiber weight ratios. Due to the hydrophilic nature of fiber, it exhibited poor interfacial interaction to hydrophobic polymer matrix. In order to enhance the interfacial interaction between fiber and polymer, the benzene diazonium salt (BDS), propionic anhydride (PA), and 3-isocyanatopropyl triethoxysilane (silane) treated jute were used for the manufacturing of composites in this study. The chemical resistance tests of prepared composites were performed in order to probe whether these are resistant to various chemicals such as: acids, alkalis, and solvents. The effect of chemical treatments of the composites have been investigated. It was observed that the fabricated composites were resistant to all chemicals except carbon tetrachloride. The treated jute composites showed higher chemical resistance than raw jute composite and silane treated jute composite yield the highest resistance which can be suggested for making the water and chemical storage tanks.

Polymeric chemosensor for the colorimetric determination of the total polyphenol index (TPI) in wines

We have developed a new method for the rapid and inexpensive determination of the total polyphenol index (TPI) in wines by simply immersing our sensory film in red or white wines and visually checking the colour change (qualitative analysis) or by analysing a photo taken of the film with a smartphone (quantitative analysis). This sensory material is straightforward and inexpensively prepared; it requires no monomer synthesis, is based on 100% commercially available monomers, and contains benzenediazonium salt motifs, which in the presence of phenols and/or polyphenol-based structures produce coloured diazo compounds. These sensory motifs are chemically anchored to the polymeric structure, and, accordingly, no migration of organic substances from the material occurs in the sensing process. Our method needs neither reagents nor sample pretreatment and has been contrasted with the standard TPI determination, i.e., measuring the absorbance of diluted wine at 280 nm, obtaining reliable data for white and red wines.

Thermo-Mechanical and Morphological Properties of Water Hyacinth Reinforced Polypropylene Composites

This paper focusses on the analysis of thermo-mechanical and morphological properties of water hyacinth (WH) fiber reinforced polypropylene (PP) biocomposites manufactured by using a single screw extruder and an injection molding machine. With a view to increasing the compatibility between the WH fibers and polypropylene matrix, raw WH fibers were chemically treated with Benzenediazonium salt in base media. Composites were manufactured with five different levels of loading (15, 20, 25, 30 and 35 wt%) of both the raw and treated WH fibers. Thermal properties of WH-PP composites were evaluated by thermogravimetric and differential thermal analyses. To analyze mechanical properties of composites, tests of tensile strength and stiffness, flexural strength and stiffness, and Charpy impact strength were carried out following ASTM standards. It was found that thermal stability and all the mechanical properties except tensile strength were improved considerably for chemically treated WH fiber composites in comparison with untreated ones. Fracture surfaces of the tensile and flexural specimens were scanned with scanning electron microscopy (SEM) to understand their surface morphologies. The SEM images clearly revealed that there were fewer fiber agglomerations, microvoids, and fiber pull out traces in treated WH-PP composites than in the untreated ones indicating better distribution of the fibers into the matrix as well as stronger fiber matrix interfacial adhesion due to treatment of WH fibers. Water absorption properties were studied to evaluate the viability of these biocomposites under specified conditions.

Conventional and Microwave‐Activated the Synthesis of a Novel Series of Imidazoles, Pyrimidines, and Thiazoles Candidates

A novel series of imidazoles, pyrimidines, and thiazoles were synthesized using microwave irradiation and conventional method from commercial available p‐aminobenzoic acid. Thus, one‐pot condensation of p‐aminobenzoic acid, urea, and chloroacetic acid have been provided two types of imidazole derivatives as separated mixture 2a and 2b. [3 + 2 + 1] Cyclocondensation of 2a, benzaldehyde, and urea/thiourea in acidic medium afforded imidazolo oxazine derivative 3 and Imidazolothiazine 4. Coupling of 2a with benzene diazonium salt gave the phenyldiazenyl imidazolidine 5. While the reaction of 2a, thiourea, and benzaldehyde in sodium ethoxide afforded imidazolothiazine 6. Oxidative cyclization of thiourea derivative 7 resulted a mixture of benzithiazole derivative 7a and oxathiazole derivative 7b. Cyclocondensation of 7a with phenylenediamine and 4‐methyl phenylenediamine furnished imidazole 8 and 9, respectively. Reaction of P‐aminobenzioc acid with potassium cyanate followed by Biginelli reaction with (acetyl acetone, ethyl acetoacetate, and diethyl malonate) and salicyladehyde in HCl tolerated pyrimidine derivatives 10a–c, respectively. In the same manner, the reactions and short reaction time make microwave technique one of the greenest methodology for synthesis of this class of heterocyclic system.

Diazonium salts for surface-confined visible light radical photopolymerization

The surface chemistry of aryl diazonium salts has progressed at a remarkable pace in the last two decades, and opened many avenues in materials science. These compounds are excellent coupling agents for polymers to surfaces via several surface-confined polymerization methods. For the first time, we demonstrate that diazonium salts are efficient for surface initiating radical photopolymerization in the visible light of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) taken as model monomers. To do so, 4-(dimethylamino)benzenediazonium salt was electroreduced on gold plates or flexible ITO sheets to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; while excited state camphorquinone acted as the free hydrogen abstractor. In the same way, we co-polymerized HEMA and MMA with ethylene glycol dimethacrylate in order to obtain crosslinked polymer grafts. We demonstrate by XPS that gold was efficiently screened by the polymer layers and that the wettability of the surfaces accounts for the hydrophilic or hydrophobic characters of the tethered polymers. Homo- and crosslinked PMMA grafts were found to resist removal by the paint stripper methyl ethyl ketone. The grafted DMA/camphorquinone system operating in the visible light holds great promises in terms of adhesion of in situ designed continuous or patterned polymer coatings on various substrates. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3506–3515

Improved thermal properties of jute fiber‐reinforced polyethylene nanocomposites

The thermal behavior of chemically modified jute fiber‐reinforced polyethylene (PE) nanocomposites was investigated. Nanocomposites were prepared by hot press molding technique using different fiber loadings (5, 10, 15, and 20 wt%) for both treated and untreated fibers. Jute fibers were chemically modified with benzene diazonium salt to increase their compatibility with the PE matrix. Surface and thermal properties were subsequently characterized. Fourier transform infrared spectroscopy and scanning electron microscopy analysis were used to study the surface morphology. Thermogravimetric analysis (TGA) and differential scanning calorimetry were carried out for thermal characterization. Fourier transform infrared spectroscopy and scanning electron microscopy study showed interfacial interaction among jute fiber, PE, and nanoclay. It was observed that, at optimum fiber content (15 wt%), treated jute fiber‐reinforced composites showed better thermal properties compared with that of untreated ones and also that nanoclay‐incorporated composites showed enhanced higher thermal properties compared with those without nanoclay. POLYM. COMPOS., 38:1266–1272, 2017. © 2015 Society of Plastics Engineers

Recent development and future trends in coir fiber‐reinforced green polymer composites: Review and evaluation

Development of natural fiber composites with thermoplastics and thermosets finds applications in various fields, from agriculture to automotive. It can reduce the dependency on petroleum resources which causes several environmental problems. Natural fibers are renewable and biodegradable that reduces carbon footprint to the environment. Coir fibers are natural fibers used in the development of composites offers comparable properties with other mineral fillers. This article reviews different methods of coir fiber modification include alkali treatment, silane treatment, hydrogen peroxide treatment, sodium hypochlorite treatment, sodium periodate treatment coupled with p‐aminophenol and urea, treatment with benzene diazonium salt and maleated coupling agent. It also reviews composites of coir fiber with thermoplastic, rubber and thermoset plastics. Hybrid composites based on coir fiber are also being discussed. Thermoplastic composites such as biodegradable (PLA, PBS) and petroleum‐based polymers (PE, PP) and thermoset polymers include polyurethane, epoxy and polyester based composites also reviewed. Degradation and biodegradation studies were reviewed in the case of biodegradable polymers. Hybrid fibers of coir with other natural and mineral fibers have recently been used in composite industry has also been reviewed. All these composites show better properties. It can be used in different applications in the field of automobile, building and construction, consumer products and furniture. POLYM. COMPOS., 37:3296–3309, 2016. © 2015 Society of Plastics Engineers

Effect of fiber treatment and nanoclay on the tensile properties of jute fiber reinforced polyethylene/clay nanocomposites

The tensile properties of chemically treated jute fiber reinforced polyethylene/clay nanocomposites were investigated. Nanocomposites were prepared using hot press moulding technique by varying jute fiber loading (5, 10, 15 and 20 wt%) for both treated and untreated fibers. Raw jute fibers were chemically treated with benzene diazonium salt to increase their compatibility with the polyethylene matrix. Physical and mechanical properties were subsequently characterized. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis was utilized to study physical properties. Tensile test was conducted for mechanical characterization. FTIR and SEM study showed interfacial interaction among jute fiber, polyethylene and nanoclay. It was observed that at optimum fiber content (15 wt%), treated composites exhibited improvements in tensile strength and modulus by approximately 20 % and 37 % respectively over the raw ones. On the other hand, this composite exhibited improvements in tensile strength and modulus by approximately 8 % and 15 % respectively over the composites without nanoclay. However, treated jute fiber reinforced composites showed better tensile properties compared with untreated ones and also nanoclay incorporated composites enhanced higher tensile properties compared without nanoclay ones.

Effect of chemical treatment on palm fibre reinforced polypropylene composites

The development of composites using lignocellulosic materials as reinforcing filler and thermoplastic polymers as matrices is currently at the centre of attention because of their low cost, lightweight, eco-friendliness and worldwide environmental awareness. In the present work, palm fibre reinforced polypropylene composites were manufactured using a single screw extruder and an injection moulding machine. Raw palm was chemically treated with benzene diazonium salt in alkali, acidic and neutral media separately to increase the compatibility of palm fibre with polypropylene matrix. Both raw and alkali, acidic and neutral media treated palm at various (15, 20, 25, 30 and 35 wt%) fibre loading were utilised during composite manufacturing. Microstructural analysis and mechanical testing were also conducted. Alkali media treated specimens yielded the best set of mechanical properties. Based on fibre loading, 30% fibre reinforced composites had the optimum set of mechanical properties among all composites manufactured.

Regular poly(para-phenylene) films bound to gold surfaces through the electrochemical reduction of diazonium salts followed by electropolymerization in an ionic liquid

By combining the electroreduction of diazonium salts and the electropolymerization of conducting polymers in an ionic liquid, the electrografting of a regular poly(para-phenylene) film on a gold substrate is achieved, leading to the strong and robust anchoring of the PPP polymers on the substrate (Au-PPP hybrid). A thin layer covalently bound to the substrate is first prepared by the reduction of benzenediazonium salt (BD), then, on top of this layer, a thicker layer of poly(para-phenylene) (PPP) is easily grown by the electrochemical oxidation of biphenyl in the [BMIm][PF6] ionic liquid. The resulting material is thoroughly characterized by IR, ToF-SIMS and fluorescence spectroscopies. The analyses show the formation of well regular PPP layers that are wired to the substrate. The key role of the [BMIm][PF6] ionic liquid in the structuration of the polymer is emphasized.

Impact of Chemical Modification on the Physical and Mechanical Properties of Tropical Wood Material

Five types of selected tropical light hardwoods were chemically modified with benzene diazonium salt to improve their physical and mechanical properties. Benzene diazonium salt underwent a coupling reaction with wood which was confirmed through FT-IR analysis. The compressive modulus of the treated wood increased, whereas modulus of rupture was shown to decrease on treatment. The modified wood samples had higher hardness (Shore D) values compared to that of the control ones.

Dual Functions of Highly Potent Graphene Derivative–Poly-l-Lysine Composites To Inhibit Bacteria and Support Human Cells

Dual-function poly(L-lysine) (PLL) composites that function as antibacterial agents and promote the growth of human cell culture have been sought by researchers for a long period. In this paper, we report the preparation of new graphene derivative-PLL composites via electrostatic interactions and covalent bonding between graphene derivatives and PLL. The resulting composites were characterized by infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The novel dual function of PLL composites, specifically antibacterial activity and biocompatibility with human cells [human adipose-derived stem cells and non-small-cell lung carcinoma cells (A549)], was carefully investigated. Graphene-DS-PLL composites composed of 4-carboxylic acid benzene diazonium salt (DS) generated more anionic carboxylic acid groups to bind to cationic PLLs, forming the most potent antibacterial agent among PLL and PLL composites with high biocompatibility with human cell culture. This dual functionality can be used to inhibit bacterial growth while enhancing human cell growth.

Effect of coupling reactions on the mechanical and biological properties of tropical wood polymer composites (WPC)

Wood polymer composites (WPCs) based on five types of selected Malaysian tropical light hardwood species were prepared using a methyl methacrylate (MMA) and hexamethylene diisocynate (HMDIC) monomer mixture at a 1:1 ratio. Before being impregnated with MMA/HMDIC, the wood species were chemically pretreated with benzene diazonium salt for the coupling reaction with wood and to increase adhesion and compatibility of the wood fiber to the polymer matrix. The monomer mixture (MMA/HMDIC) was impregnated into both the raw wood and diazonium salt pretreated wood specimens to manufacture wood polymer composites (WPC) and pretreated wood polymer composites (PWPC), respectively. Microstructural analysis (scanning electron microscopy and Fourier transform infrared spectroscopy) and mechanical (three-point bending and compression) and biological (fungal decay resistance) tests were conducted. Comparisons were made among the properties of raw wood, WPC, and PWPC. The results reveal that PWPC yielded better mechanical and biological properties compared to untreated WPC and raw wood.

Diazonium Salt-Derived 4-(Dimethylamino)phenyl Groups as Hydrogen Donors in Surface-Confined Radical Photopolymerization for Bioactive Poly(2-hydroxyethyl methacrylate) Grafts

In this paper we describe a novel methodology for grafting polymers via radical photopolymerization initiated on gold surfaces by aryl layers from diazonium salt precursors. The parent 4-(dimethylamino)benzenediazonium salt was electroreduced on a gold surface to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; free benzophenone in solution was used as a photosensitizer to strip hydrogen from the grafted DMA. This system permitted efficient surface initiation of photopolymerization of 2-hydroxyethyl methacrylate. The resulting poly(2-hydroxyethyl methacrylate) (PHEMA) grafts were found to be very adherent to the surface as they resist total failure after being soaked in the well-known paint stripper methyl ethyl ketone. The PHEMA grafts were reacted with 1,1'-carbonyldiimidazole to yield carbamate groups that are able to react readily with amino groups from proteins. The final surface consisted of protein-functionalized PHEMA grafts where bovine serum albumin (BSA) protein is specifically linked to the grafts by covalent bonds. We used X-ray photoelectron spectroscopy to monitor the chemical changes at the gold surface all along the process from the neat gold to the end-protein-functionalized polymer grafts: the PHEMA graft thickness ranged from 7 to 27 nm, and the activation by 1,1'-carbonyldiimidazole reached 37% of the OH groups, which was sufficient for 90% surface coverage of the grafts by BSA. This work conclusively provides a new approach for bridging reactive and functional polymers to surfaces via aryl diazonium salts in a simple, fast, and efficient approach of importance in biomedical and other applications.

Physico‐mechanical and decay resistance properties of chemically modified tropical wood material

AbstractIn this present research, several kinds of selected tropical light hardwoods were chemically modified with benzene diazonium salt to improve their physico‐mechanical and decay resistance properties. Benzene diazonium salt underwent a coupling reaction with wood which was confirmed through fourier transform infrared spectroscopic analysis. The compressive modulus of the treated wood increased, whereas modulus of rupture was shown to decrease on treatment. Water absorption was also found to decrease considerably after modification. The modified wood samples had higher hardness (Shore D) value compared to that of the control ones. The wood was exposed to two types of fungi; white‐rot (Polyporus versicolor) and brown‐rot (Postia placenta), for 12 weeks and then decay was assessed through weight loss percentage (%). A significant improvement was found in the modified wood compared to the control wood. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013