Synthesis and characterization of reactive blocked‐isocyanate coupling agents from methyl ethyl ketoxime,ethyl cellosolve/ε‐caprolactam blocked aromatic and aliphatic diisocyanates

A series of water‐dispersible blocked polyisocyanates were synthesized from toluene 2,4‐diisocyanate (TDI), isophorone diisocyanate (IPDI), dimethylol propionic acid, methyl ethyl ketoxime (MEKO), ethyl cellosolve (EC), and ?‐caprolactam (CL). The physical properties, such as the viscosity, pH, and storage stability, of the blocked‐polyisocyanate adducts were measured. All aqueous dispersions of the blocked polyisocyanates showed good storage stability. The prepared blocked polyisocyanates were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and thermogravimetric analysis techniques. The FTIR confirmed that the ? NCO groups of the original TDI and IPDI molecules were completely blocked by the blocking agents. The thermal analysis measurements revealed that both the blocked TDI‐ and IPDI‐based polyisocyanates started to deblock at about 55–85°C. Compared to the CL‐blocked polyisocyanates, the MEKO‐ and EC‐blocked polyisocyanates had lower thermal dissociation temperatures and faster deblocking rates. We also found that the initial deblocking temperatures of the TDI‐based adducts were lower than those of the IPDI‐based adducts. The water resistance and tensile properties of the composite films from the blocked‐polyisocyanate crosslinkers and hydroxyl–polyurethane emulsion (HPUE) matrix were studied. The tensile strength increased and the elongation at break were lower in the composites compared to the pure HPUE film. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel anti‐bacterial acid dyes derived from naphthalimide: synthesis,characterisation and evaluation of their technical properties on nylon 6

As an attempt to combine the dyeing and functional finishing steps into one process, two novel anti‐bacterial monoazo acid dyes based on N‐ester‐1,8‐naphthalimide were synthesised. To do this, 4‐amino‐N‐ethyl glycinate‐1,8‐naphthalimide was prepared, diazotised and then coupled to thiosalicylic acid or salicylic acid to produce anti‐bacterial dyes. The synthesised dyes were purified and then fully characterised using Fourier Transform–infrared spectrometry, proton nuclear magnetic resonance spectroscopy and melting point analysis. Dispersion of the dyes was prepared in water and applied to nylon 6 fabrics. The novel dyes offered good build‐up properties on the substrate. The anti‐bacterial efficacy of the synthesised dyes was assessed, with the dyes showing activity against both Gram‐positive and Gram‐negative bacteria.     

Synthesis of yellow pyridonylazo colorants and their application in dye–pigment hybrid colour filters for liquid crystal display

Nine yellow azo dyes were designed and synthesised by using different diazo components and pyridonyl coupling components for application in dye–pigment hybrid colour filters for liquid crystal displays. The synthesised dyes were characterised by proton nuclear magnetic resonance and elemental analysis. The thermal stability was examined by thermogravimetric analysis, and solubility was estimated in industrial solvents such as N-methyl-2-pyrrolidone and propylene glycol methyl ether acetate. The dyes, which exhibited suitable physical properties for use in a dye–pigment hybrid colour filter, were fabricated into colour filters, and their optical properties were measured.     

Cure-reaction kinetics of amine-blocked polyisocyanates with alcohol using hot-stage Fourier transform infrared spectroscopy

Cure reaction between a series of N-methylaniline-blocked polyisocyanates, based on 4,4′-methylenebis(phenyl isocyanate), poly(tetrahydrofuran) and several substituted N-methylanilines, and n-decanol has been studied. The solid-state isothermal cure reaction was carried out using hot-stage FTIR spectroscopy, in the temperature range of 125–145°C. The urea carbonyl absorption band of blocked polyisocyanate moiety was used to monitor the conversion of blocked polyisocyanate into polyurethane. Kinetic and thermodynamic parameters were calculated using normalized conversion curves. The overall order of cure reaction, for each of the blocked polyisocyanates was found to be first order. Based on the results of kinetics and reaction conditions used in this study, the elimination-addition (S_N¹) mechanism was suggested for the cure reaction between N-methylaniline-blocked polyisocyanates and n-decanol. The effect of substituents present in the blocking agents on the cure reaction of N-methylaniline-blocked polyisocyanates was investigated and found that the cure reaction of N-methylaniline-blocked polyisocyanates was retarded by electron-donating substituents and facilitated by electron withdrawing substituents. The observed high negative entropy of activation value supports the formation of a four-centered, intramolecularly hydrogen-bonded ring structure during transition state of the cure reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cationic azomethine disperse dyes: Synthesis,antifungal activity and tinctorial properties of N-arylideneamino p-substituted pyridinium salts as possible dyes for synthetic fibres

In a four-step synthesis, a series of N-arylideneamino p-substituted pyridinium salt derivatives were prepared for use as cationic azomethine disperse dyes for polyester and polyacrylonitrile fibres. The effect of different substituents, in both of homo- and heterocyclic ring systems, on position of maximum absorbance in UV-vis spectra was used to explain the different hues of the prepared dyes. Besides, showing promising tinctorial properties, the synthesised dyes revealed fungicidal activity against Aspergillus niger. The structure of the hitherto prepared dyes was inferred by elemental and spectral data.     

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β‐sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant‐free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β‐sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4‐diethylamino‐4′‐(2‐sulphatoethylsulphonyl‐4,6‐dibromo)azobenzene dyes were prepared by a diazo‐coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build‐up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.     

Synthesis and application of some novel antimicrobial monoazonaphthalimide dyes: synthesis and characterisation

A series of novel monoazo dyes based on N‐pyridine‐1,8‐naphthalimides were prepared using 4‐amino‐N‐2‐aminomethylpyridine‐1,8‐naphthalimide as the diazo component and N,N‐diethyl‐meta‐toluidine, 3‐(N,N‐diethylamino)acetanilide and N‐hydroxyethyl‐N‐ethylaniline as the coupling components. The synthesised dyes were purified by utilising column and preparative thin‐layer chromatography methods. The characterisations of the prepared dyes were carried out by differential scanning calorimetery, thin‐layer chromatography (R_f values), Fourier Transform infrared, and proton and carbon nuclear magnetic resonance techniques. The in vitro antibacterial activity of the novel synthesised compounds against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and their antifungal activity against Candida albicans were evaluated by use of conventional agar dilution procedures and a minimum inhibitory concentration. Some of these synthesised dyes demonstrated antibacterial activity against Gram‐positive bacteria in addition to antifungal activities.     

Synthesis and colour spectroscopic investigation of some hemicyanine dyes

New hemicyanine dyes with a benzo[2,3‐b;2′,3′‐b′]bis‐furo[3,2‐d]pyrazolium nucleus were prepared. Spectroscopic investigations were carried out in 95% ethanol for all the synthesised cyanine dyes and/or in pure solvents which have different polarities for some selected dyes. Structural identification was carried out via elemental analysis, infra‐red and proton nuclear magnetic resonance spectral data.     

Synthesis of novel polymeric colorants

There are several structural types of polymeric dyes (polydyes) that have been synthesised as colorants for thermoplastic materials, particularly polyesters. This paper reviews three synthetic methods used to prepare polydyes. In method 1, anthraquinone polysulphonamide polydyes were prepared by reacting anthraquinonedisulphonyl chlorides with diamines in the presence of a base. Polymethine polydyes were prepared in method 2 by reacting bis-aldehydes containing two linked aromatic aldehyde moieties with a bis-(active methylene) component under Knoevenagel reaction conditions. In the final method, a variety of polymer types were synthesised by reacting acidic dyes containing two acidic groups with glycol sulphonates in the presence of a base. Most of the polydyes were evaluated as colorants for polyesters, by melt blending and extruding, followed by the preparation of films for further testing of properties such as fastness to light. The primary emphasis of this paper is to discuss the synthetic methods involved and to present the various types of structure that have been investigated.     

A facile synthesis and tautomeric structure of novel 4‐arylhydrazono‐3‐(2‐hydroxyphenyl)‐2‐pyrazolin‐5‐ones and their application as disperse dyes

The main target of this paper was the synthesis of novel azo disperse dyes with better dyeing properties, together with a systematic investigation to determine their dominant tautomer(s) from 12 possible tautomeric structures. In this regard, novel azopyrazolin‐5‐one dyes were synthesised via the reaction of hydrazine hydrate with 2,3,4‐chromantrione‐3‐arylhydrazones. The acid dissociation constants both in the ground and in the excited state for the series prepared were determined and correlated by the Hammett equation. The results of this correlation, together with spectral data, indicated that the compounds under scrutiny exist predominantly in the keto‐hydrazo structure as a Z‐configuration, both in the ground and in the excited state. Finally, the synthesised dyes were applied as disperse dyes for dyeing polyester fabrics, and their fastness properties were evaluated. Also, the position of colour in CIELAB coordinates was estimated and discussed.     

Addition polyimides. I. Kinetics of cure reaction and thermal decomposition of bismaleimides

The thermal polymerization of four structurally different bismaleimide resins, prepared by reacting maleic anhydride with four aromatic diamines, viz., 4,4′-diaminodiphenyl methane, 4,4′-diamino diphenyl ether, 4,4′-diamino diphenyl sulfone, and 3,3′-diamino diphenyl sulfone, was followed by differential scanning calorimetry (DSC). The enthalpy change and the kinetic constants for the polymerization reactions were evaluated from the DSC curves. Thermal stability of the cured polymers was studied by thermogravimetry (TG). The kinetic parameters, viz., activation energy E and preexponential factor A, for the thermal decomposition of the cured bismaleimides were calculated from the TG curves using three nonmechanistic integral equations. The kinetic constants (E and A) follow a trend similar to the thermal stability of the polymers.     

Synthesis and properties of novel rosin‐based water‐borne polyurethane

A series of novel rosin‐based water‐borne polyurethanes (RWPUs) was prepared from fumaropimaric acid polyester polyol (FAPP) synthesised from rosin acid. Emulsions of the prepared RWPUs were investigated by transmission electron microscopy, and dried films of the emulsions were characterised by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction and differential scanning calorimetry. Other properties including water absorption, tensile strength, elongation at break, and antibacterial activity of the RWPUs were also determined. The results suggest that RWPU prepared with 35 wt% FAPP has good potential for applications, with improved mechanical properties, thermal stability and water resistance. The RWPU showed excellent antimicrobial properties in killing both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. Copyright © 2011 Society of Chemical Industry     

Dyes derived from 3‐formyl‐2(1H)‐quinolone – synthesis,spectroscopic characterisation,and their behaviour in the presence of sulfhydryl and non‐sulfhydryl amino acids

Novel dyes based on a 3‐formyl‐2(1H)‐quinolone skeleton were synthesised and characterised using ¹H nuclear magnetic resonance spectroscopy and mass spectrometry. The spectroscopic properties of these dyes, such as their absorption spectra, emission spectra, and quantum fluorescence yields, were also examined. The behaviour of the obtained compounds at a pH of 7.4 in the absence and in the presence of thiol amino acids, such as l ‐cysteine, l ‐glutathione, and N‐acetyl‐l ‐cysteine, were studied. The spectroscopic responses of the tested dyes towards other amino acids were also investigated. A reference compound was synthesised to understand the reaction mechanism between the thiols and the obtained dyes. The experimental results show that the synthesised dyes have the potential to act as sensors for thiols.     

Metal-complex Dyes for Wool and Nylon — 1930 to date

An introduction outlining the scope and limitations of this paper is followed by a brief explanation of the essential structural features of metal-complex dyes. The earliest metal-complex dyes were produced directly within the fibre material by reacting a metallisable dye with a chromium compound in situ. The first chromium complex dyes prepared in substance, were the chromium complexes containing sulpho-groups, synthesised by R Bohn of BASF, in 1912, the application of which was first made possible after the discovery by Ciba of a satisfactory dyeing process based on the use of a dyebath made strongly acid with sulphuric acid. These two classes of dye dominated the dyeing industry into the 1950s. At that time 1:2 metal-complex dyes without sulphonic acid groups but containing nonionic substituents as solubilising groups were introduced. These complexes were applicable from neutral to weakly acid dyebaths, which minimised the damage to the fibres. These dyeings were characterised by high fastness to light and wet treatments. Later, for commercial reasons, sulphonic acid groups were again introduced into the dye molecule to increase their hydrophilic properties. These dyes also have become well established as a result of the introduction of new dyeing methods and the development of dyeing auxiliaries designed to promote level dyeing. In addition to these types of metal-complex dyes, further metal-complex dyes selected from the extensive patent literature of the last 50 years because of their interesting structure are described.     

Phenol–formaldehyde resins modified by copper nanoparticles

Abstract

Phenol–formaldehyde (PF) resins modified by copper nanoparticles were synthesised by in situ polymerisation process. X-ray diffraction (XRD), transmission electron microscopy (TEM) revealed that nanosized copper particles were well dispersed in the resulting PF resins. The thermal properties of the prepared PF resins were investigated by thermogravimetric analysis (TGA). It was indicated that copper nanoparticles remarkably improved the thermal stability of the PF resins at lower temperature. However, the copper nanoparticles increased the rate of the degradation of the PF resins at the elevated temperature. The toughness and the tribological properties of the friction materials based on the prepared PF resins were also studied. The results showed that copper nanoparticles obviously improved the brittleness and the tribological performances of the friction materials.     

Synthesis and characterisation of benzothiazole‐based solid‐state fluorescent azo dyes

Novel solid‐state fluorescent azo dyes containing a 2‐[4‐(dimethylamino)phenyl]benzo[d]thiazol‐6‐amine as the electron donor group were synthesised. These dyes showed a molar extinction coefficient in the range of 20 000–30 000 l/mol/cm. These compounds were characterised by strong solid‐state fluorescence under long ultraviolet light (365 nm). Absorption and fluorescence spectra revealed that electron coupling originating from broad π‐electron delocalisation and the keto–enol form is responsible for the large Stokes shift. These dyes were readily soluble in common solvents such as dichloromethane, chloroform, dimethyl formamide , tetrahydrofuran and dimethyl sulphoxide and were characterised by means of elemental analysis, proton nuclear magnetic resonance and mass spectrometry. Thermogravimetric analysis of solid‐state fluorescent dyes show thermal stability up to 270 °C and can therefore be used for polymer application. The coloristic properties of these dyes were evaluated on polyester by the disperse dyeing method.     

Dyeing of poly(lactic acid) fibres with synthesised novel heterocyclic disazo disperse dyes

Poly(lactic acid) (PLA) is the first melt‐processable, renewable, sustainable and biodegradable natural‐based synthetic fibre. It has a broad range of uses and combines ecological advantages with outstanding performance in textiles. PLA fibre, as an aliphatic polyester, can be dyed with disperse dyes. Apart from the limited number of commercial disperse dyes, disperse dye exhaustion on PLA is generally lower than that on  poly(ethylene terephthalate) (PET). In this study, new heterocyclic disazo disperse dyes, substituted with methyl, nitro and chloro groups at their ortho‐, meta‐ and para‐ positions, synthesised in our previous study, were applied to PLA and PET fibres to examine their dyeing performance, and colour fastness and dye exhaustion properties. Different shades of yellow, orange, reddish brown and brown were obtained. Most of the synthesised novel heterocyclic disazo disperse dyes exhibited good build‐up properties with high K/S levels on both fibres. Para‐ bonding substituent provided higher K/S values than meta‐ and ortho‐ positions for –NO₂ and –Cl substituents for both fibres. Overall, the most synthesised novel heterocyclic disazo disperse dyes in this study exhibited good build‐up properties with high K/S, exhaustion and wet fastness levels on both PLA and PET fibres.      

Effect of Methyl Group on Acyclic Serinol Scaffold for Tethering Dyes on the DNA Duplex Stability

Acyclic serinol derivatives are useful scaffolds for tethering dyes within DNA duplexes. Here we synthesised an inverse l ‐threoninol (il ‐threoninol) scaffold and compared its effect on DNA duplex stability to other acyclic artificial nucleic acid scaffolds that are based on d ‐threoninol, l ‐threoninol, and serinol. When planar trans‐azobenzene was incorporated into the DNA duplex through a single bulge‐like motif (the wedge), the il ‐threoninol scaffold stabilised the duplex most efficiently. When scaffolds were incorporated in complementary positions (dimer motif) or in three adjacent positions (cluster motif), d ‐threoninol was the most stabilising. CD spectra indicated that the effect of scaffold on the duplex stability was closely related to the winding induced by each scaffold. When trans‐azobenzene was photo‐isomerised to non‐planar cis‐azobenzene, il ‐threoninol destabilised the duplex most strongly, irrespective of the number of artificial residues incorporated. The properties of the il ‐threoninol scaffold make it a useful tether for dyes or other functionalities.     

Synthesis,physical and thermal characterization of phosphorus-containing homopolymers and copolymers based on 2,4-bis(4-aminophenoxy)-6-diethoxyphosphinyl-s-triazine

Novel phosphorus-containing homopolyimides, homopolyamides, and homopolyureas were prepared by reacting 2,4-bis(4-aminophenoxy)-6-diethoxyphosphinyl-s-triazine (BADT) with pyromellitic or benzophenone tetracarboxylic dianhydride, terephthaloyl chloride, and tolylene diisocyanate, respectively. In addition, the corresponding copolymers that contained approximately 3% phosphorus were prepared by reacting BADT and 4,4′-diaminodiphenyl sulfone with the aforementioned reagents. These polymers were characterized by inherent viscosity measurements, infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy as well as by differential thermal analysis (DTA) and dynamic thermogravimetric analysis (TGA). Their thermal properties were compared with those of the corresponding nonphosphorylated polymers. The copolymers were stable up to 233–272°C in nitrogen or air atmosphere. The homopolymers showed a relatively lower thermal stability. Furthermore, a model diimide, diamide, and diurea were synthesized from the reactions of BADT with phthalic anhydride, benzoyl chloride, and phenyl isocyanate, respectively. The physical and thermal characteristics of these model compounds were correlated with those of the corresponding homopolymers.     

Preparation of porous spodumene/zircon composite ceramics and its thermal and mechanical properties

Abstract

Porous β-spodumene/zircon (ZrSiO₄) composite ceramics were prepared by addition of zirconia to spodumene mineral using conventional solid reaction methods. The formation of the zircon was investigated by means of the differential scan calorimetry measurements and an X-Ray diffractometer. The microstructure of the composite ceramics was observed through a scanning electron microscope. The results show that the presence of zircon benefited the formation and stability of the porous structure and improved significantly the thermal endurance and mechanical properties of the spodumene matrix. The composites with 10–15% porosity exhibit an excellent thermal shock resistance, a low thermal expansion coefficient of approximately 1·4 × 10^?6 K^?1 in the range of 200–800°C and a high flexural strength about 100 MPa. It is found that the spodumene/zircon composites, widely used as a high temperature structure material, can be synthesised by a cost effective method.