Triethylenetetramine Research Articles

CuBr coordinated by the ionic liquid [N4MIM]Cl as a catalyst for biphasic ATRP in 1-allyl-3-methylimidazolium chloride ionic liquid

The ionic liquid 1-(triethylene-tetramine)ethyl-3-methyl chloride ([N4MIM]Cl) was first prepared to replace the organic ligand coordinating with CuBr to catalyze atom-transfer radical polymerization (ATRP) in ionic liquid system. [N4MIM]Cl was synthesized via the intermediate IL 1-chloroethyl-3-methyl chloride ([CeMIM]Cl) reacting with the aliphatic amine triethylene tetramine (TETA) and [CeMIM]Cl) was obtained by N′-alkylation of N-methylimidazole with 1,2-dichloroethane. This catalyst has been applied to the ATRP of methyl methacrylate (MMA) in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) and presented a perfect catalytic performance. The chemical structures of the ILs obtained were confirmed by FTIR and 1HNMR. The coordination ability of [N4MIM]Cl was assessed by cyclic voltammetry (CV) and its coordination mechanism towards CuBr was discussed. The [N4MIM]Cl/CuBr catalyst system showed good controllability in the aforementioned ATRP reaction in [AMIM]Cl. The amount of residual Cu2+ in the polymer product was determined by atomic absorption spectrometry (AAS) and the result showed that the Cu catalyst was easily separated from the obtained polymer. Thus, the coordinating IL could overcome the shortcomings of traditional organic ligands, such as poor compatibility with IL media resulting in the weakly catalytic performance and inferior separation of the catalyst from the polymer. It implied that the coordinating ionic liquid ([N4MIM]Cl) has highly promising application in the ATRP of ionic liquid system.

Synthesis, characterization of amino-modified walnut shell and adsorption for Pb(II) ions from aqueous solution

In this paper, a biodegradable, green, easy renewable heavy metal capture agent, amino-modified walnut shell (AMWNS), was synthesized, and the adsorption behavior for Pb(II) ions from aqueous solution was also investigated. The AMWNS was prepared, where triethylene tetramine (TETA) was used as modified monomer, and the structure of AMWNS was characterized by Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction and thermogravimetric analysis. Then, adsorption capacity of AMWNS for Pb(II) was investigated in different pH (2–9) and different adsorbent dosage (0.5–2.0 g/L), and the result showed when solution pH value was 7, the adsorption capacity of the AMWNS on Pb(II) ions was optimal. The maximum Pb(II) ions adsorption capacity (Qm) obtained by Langmuir fitting model was 56.81 mg/g at 298 K. The adsorption kinetics was well confirmed by pseudo-second-order equation. The results of thermodynamic studies showed the adsorption of AMWNS for Pb(II) ions was an endothermic reaction and spontaneous process. Furthermore, the result showed AMWNS had excellent regeneration capability.

Preparation and Characterization of Nanosized Bi-Doped SnO₂/Reduced Graphene Oxide 3D Hybrids for Visible-Light-Driven Photocatalysis.

The nanosized Bi-doped SnO2/reduced graphene oxide 3D hybrids have been synthesized via one-step hydrothermal method. The structures, morphologies, photocatalytic activities of the as-prepared samples were discussed, respectively. The formation mechanism of the as-prepared hybrids was also proposed. Experimental results indicated that the usage amount of Bi2Sn2O7 obviously affected the photocatalytic performance of the as-prepared products. When it was 450 mg, the as-prepared sample possessed the band gap energy of 1.9 eV and the photocatalytic efficiency of 90% in 210 min for degradation of rhodamine B solution. In addition, triethylene tetramine and the as-prepared carbon hydrogel could act as reductant to synergistically reduce Bi2Sn2O7 into Bi-doped SnO2 particles during the formation of the hybrids.

Preparation of Phthalocyanine Immobilized Bacterial Cellulose Nanocomposites for Decoloration of Dye Wastewater: Key Role of Spacers

We report the preparation of a series of spacer-incorporated, tetra-amino cobalt (II) phthalocyanine (CoPc)-immobilized bacterial cellulose (BC) functional nanocomposites (CoPc@s-BC). Four kinds of flexible spacers with different lengths—diethylenetriamine (DT), triethylenetetramine (TT), tetraethylenepentamine (TP) and pentaethylenehexamine (PH)—were covalently attached onto pre-oxidized BC for the synthesis of the spacer-attached BC, and the attached spacers’ contents were carefully quantified. Using glutaraldehyde as a cross-linker, the CoPc catalyst was covalently immobilized onto the spacer-attached BC, and the immobilization steps were optimized by monitoring both the residual spacer contents and the resulting immobilized CoPc. All of the functionalization processes were characterized and confirmed by X-ray photoelectron spectroscopy (XPS). The series of spacer-incorporated, CoPc-immobilized BC nanocomposites, CoPc@s-BC, were used for the decoloration of dye wastewater. Both the adsorption capacity and adsorption rate were increased after the incorporation of spacers. When H2O2 was employed as an oxidant, dye molecules were catalytically oxidized with these nanocomposites. Electron paramagnetic resonance (EPR) spin-trapping results showed that the highly reactive hydroxyl radical (·OH) was involved in the catalytic oxidation process. The spacer length had a direct effect on the catalytic efficiency of CoPc@s-BC—the decoloration rate for CoPc@TP-BC was as high as 41 μmol·min−1·g−1, which was more than 50% higher than that without spacer.

Enhanced electrochemical performance of hyperbranched poly(amidographene)

We report a facile route for the synthesis of hyperbranched polyamido-graphenes (HBP(A-G)) as non-metallic high capacity electrodes for charge storage in supercapacitors. HBP(A-G) were synthesized by Michael addition of polyamines, ethylene diamine (EDA), diethylene triamine (DETA), triethylene tetraamine (TETA), to acrylamide grafted graphene oxide, followed by reduction in situ. A 3D network of stiff graphene sheets connected by flexible polyamine chain was formed. Hyperbranching increased d-spacing and BET surface area of graphene stacks, which enhanced accessibility of sites for ion storage, and prevented restacking. HBP(A-G) electrodes displayed electric double layer capacitance behaviour with excellent specific capacitance. The charge storage capacity of the electrodes increased with an increase in the amine chain length. Specific capacitance of electrodes containing HBP(TETA-G) was found to be 269 F g-1 in a symmetric two electrode electrochemical cell, using 1 M H2SO4 electrolyte at a current density of 1 A g-1 for voltage range of 0–1 V. An increase in the length of amine chains improved ion mobility, lowered equivalent distributed resistance and time constant of the electrodes. The time constant of HBP(TETA-G) capacitor was only 538 ms. Hydrophilic amine linkages on graphene backbone provided stability against electrode volume changes during charging and discharging and gave 89% capacity retention over 10,000 cycles at 10 A g-1 current density for HBP(TETA-G) electrodes. HBP(A-G) electrodes demonstrated superior performance as electrodes for supercapacitors and has shown potential for use in other electrochemical applications.

Carbon composite lignin-based adsorbents for the adsorption of dyes

Carbon composite lignin-based adsorbent were prepared through hydrothermal method with glucose as carbon source, calcium lignosulfonate and triethylene tetramine as raw materials, respectively. The optimum synthesis conditions were determined by investigating the addition of carbon and triethylene tetramine. The adsorbent was used for the adsorption of azo dyes Congo red and Eriochrome blue black R, and the five factors affecting the adsorption were discussed, including pH of dyes, initial concentration, adsorption time, adsorption temperature and adsorbent dosage. The corresponding adsorption mechanism such as pseudo first order kinetics, pseudo second order kinetics, intraparticle diffusion, Langmuir adsorption isotherm, Freundlich isotherm, Temkin isotherm, Dubinin-Radushkevich adsorption isotherm, thermodynamics were also studied. When the dye concentration is 40 mg L−1, Congo red and Eriochrome blue black R dye removal rates reach 99%. Moreover, the adsorption process of two kinds of dyes follow the pseudo second order kinetics and the Langmuir adsorption isotherm.

Catalytic transesterification of Pistacia chinensis seed oil using HPW immobilized on magnetic composite graphene oxide/cellulose microspheres

Abstract In the present study, magnetic composite graphene oxide/cellulose (GO/CM@Fe3O4) microspheres were prepared as support material, which are cost-efficient, non-toxic and environmental friendly. The microspheres with higher adsorption capacity were further modified using triethylene tetramine (TETA), and H3PW12O40 (HPW) was immobilized to form GO/CM-NH2@Fe3O4-HPW microspheres as heterogeneous catalyst for biodiesel production. The novel heterogeneous catalyst was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) and X-ray diffractometry (XRD). For the first time, GO/CM-NH2@Fe3O4--HPW was applied in the transesterification of highly-acidic Pistacia chinensis seed oil to biodiesel. Under optimal reaction conditions 80 °C, methanol/oil molar ratio 12:1, catalyst 15 wt% (w/w of oil) for 8 h, a 94% biodiesel yield was achieved. The heterogeneous catalyst could be easily separated from the reaction system by using magnetic field and efficiently recycled for at least six times. This novel procedure overcomes the disadvantages of the current catalyst support such as active site leaching, complicated preparation process and high costs. Therefore, it was a potential novel heterogeneous catalyst for biodiesel production.

Selective Adsorption of Pb(II) from Aqueous Solution by Triethylenetetramine-Grafted Polyacrylamide/Vermiculite.

Amine groups play significant roles in polymeric composites for heavy metals removal. However, generating a composite with a large number of functional and stable amine groups based on clay is still a challenge. In this work, a new amine-functionalized adsorbent based on acid-activated vermiculite (a-Verm) was prepared by organic modification of silane coupling agent as bridge, followed by in situ polymerization of acrylamide (AM) and further grafting of triethylene tetramine (TETA). The obtained polymeric composite g-PAM/OVerm was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared (FTIR), thermal analysis (TG/DTG), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analyses, confirming that amine groups were successfully grafted onto the surface of Verm. The efficacy g-PAM/OVerm for removing Pb(II) was tested. The adsorption equilibrium data on g-PAM/OVerm was in good accordance with the Langmuir adsorption isotherms, and the adsorption maximal value of Pb(II) was 219.4 mg·g−1. The adsorption kinetic data fit the pseudo-second-order kinetic model well. Additionally, g-PAM/OVerm has better selectivity for Pb(II) ion in comparison with Zn(II), Cd(II) and Cu(II) ions. The present work shows that g-PAM/OVerm holds great potential for removing Pb(II) from wastewater, and provides a new and efficient method for the removal of heavy metal ions from industrial wastewater.

Preparation of sub 3 nm copper nanoparticles by microwave irradiation in the presence of triethylene tetramin

The preparation of sub 3 nm copper nanoparticles (CuNPs) in ethylene glycol (EG) using triethylene tetramine (TETA) as chelating and reducing agents via a rapid microwave (MW) irradiation is reported. The sub 3 nm CuNPs after MW irradiation are clearly seen from the electronic micrographs. The firm chelation of Cu2+ by TETA is illustrated by the dark blue color of Cu2+/TETA/EG solution and the redox reaction is confirmed by the appearance of red color of the mixtures. The optimal mole ratio of TETA/Cu2+ is found to be 2.5/1 for preparing sub 3 nm CuNPs under the MW irradiation, operated at 800 W for 1 min. The plasmonic absorption λmax demonstrated in UV–vis spectra are found to close to 200 nm for sub 3 nm CuNPs, comparing to 500 ∼ 600 nm for regular, larger CuNPs. The extremely low Tm around 30 °C and the fusion/recrystallization sequence of sub 3 nm CuNPs can be directly measured by their differential scanning calorimetry thermograms.

Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates

In this study, azomethine polyphosphonates were synthesized by solution polycondensation of phenylphosphonic dichloride with various azomethine diols such as [4-(4-hydroxy phenyl) iminomethyl] phenol, [(4-(4-hydroxy-3-methoxy phenyl) iminomethyl)] phenol and [4-(4-hydroxy-3-ethoxy phenyl) iminomethyl] phenol using triethylamine catalyst at ambient temperature. The structure of the synthesized polymers was confirmed by Fourier transform infrared and 1H-, 13C- and 31P- nuclear magnetic resonance spectroscopic techniques. Thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. The TGA data showed that the synthesized polyphosphonates produce high char yield at 600°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. One of the synthesized polyphosphonate was blended with commercial diglycidyl ether of bisphenol-A (DGEBA) resin in various weight percentage and cured with commercial curing agent triethylene tetramine (TETA). The polyphosphonates-blended epoxy thermosets have tensile strength in the range of 5–41 MPa and the percentage of elongation at breaks was 4–18. It was found that the incorporation of polyphosphonates into epoxy thermoset decreased the tensile strength from 41 MPa to 5 MPa, whereas the elongation at break value increased with increase in the weight percentage of polyphosphonate. The influence of polyphosphonates on the flame retardancy of blended thermosets was examined by limiting oxygen index (LOI) and vertical burning (UL-94) tests and found that the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 24–26. Broido and Horowitz–Metzger methods have been used to study the thermal degradation kinetic parameters.

Semitransparent Flexible Organic Solar Cells Employing Doped-Graphene Layers as Anode and Cathode Electrodes.

Semitransparent flexible photovoltaic cells are advantageous for effective use of solar energy in many areas such as building-integrated solar-power generation and portable photovoltaic chargers. We report semitransparent and flexible organic solar cells (FOSCs) with high aperture, composed of doped graphene layers, ZnO, P3HT:PCBM, and PEDOT:PSS as anode/cathode transparent conductive electrodes (TCEs), electron transport layer, photoactive layer, and hole transport layer, respectively, fabricated based on simple solution processing. The FOSCs do not only harvest solar energy from ultraviolet-visible region but are also less sensitive to near-infrared photons, indicating semitransparency. For the anode/cathode TCEs, graphene is doped with bis(trifluoromethanesulfonyl)-amide or triethylene tetramine, respectively. Power conversion efficiency (PCE) of 3.12% is obtained from the fundamental FOSC structure, and the PCE is further enhanced to 4.23% by adding an Al reflective mirror on the top or bottom side of the FOSCs. The FOSCs also exhibit remarkable mechanical flexibilities through bending tests for various curvature radii.

Directional Interlaminar Shear Strength (ILSS) of nano-modified epoxy/unidirectional glass fibre composite

Researchers have found that the mechanical properties of the polymer composites may be enhanced by the modification of the matrix by the addition of nanoparticles. While most of the previous literatures are limited only to two-phase systems, the outcome of this work has introduced a three-phase composite developed with nano-materials as additional reinforcements. As most of the composites are neither homogeneous nor isotropic, it is highly important to understand the influence of nano-modification of the matrix on the mechanical properties of unidirectional (UD) fibre reinforced composites. In this work, diglycidyl ether of bisphenol A (DGEBA)/triethylene tetramine (TETA) system is nano-modified by the addition of alumina and zirconia nanoparticles. The unidirectional glass fibres are used along with the unmodified and modified epoxy resins for fabricating composite laminates by vacuum bagging process. The interlaminar shear tests were performed over the specimens machined from various laminates prepared out of neat and nano-modified samples. The interlaminar shear strength (ILSS) of the composite is investigated at different angles (longitudinal, transverse and 45°) of the fibres. Though the ILSS of the fabricated composites is greater along the longitudinal direction, the enhancements in the ILSS by the addition of nano-fillers were higher along transverse direction. This is because of the dominant properties of matrix at transverse direction. Any changes in the properties of the matrix influence a lot on ILSS of the composite along the transverse direction. Further, due to the larger specific surface area (SSA) of the alumina nanoparticles, the ILSS of the composite containing alumina nano-fillers is found to be superior to the composites filled with zirconia nanoparticles at similar particle size and loading.

Performance and Mechanisms of Triethylene Tetramine (TETA) and 2-Amino-2-methyl-1-propanol (AMP) in Aqueous and Nonaqueous Solutions for CO2 Capture

Nonaqueous amines are currently being explored for energy-efficient postcombustion CO2 capture, but the absorption capacity and regeneration efficiency of most absorbents still need to be further improved. In this work, a mixture of triethylene tetramine (TETA) and 2-amino-2-methyl-1-propanol (AMP) dissolved in ethanol was chosen as a nonaqueous absorbent for CO2 capture and performed with high absorption loading and regeneration efficiency. In addition, the changes of the components during the absorption–desorption process and reaction mechanisms of nonaqueous absorbents were explored by 13C NMR spectroscopy and compared with those of aqueous absorbents. The results showed that TETA/AMP/ethanol had higher absorption loading and regeneration efficiency (3.71 mol kg–1, 95.4%) after the fifth regeneration cycle than TETA/AMP/water (3.54 mol kg–1, 38.8%) when the amine mass concentration was 40 wt %. CO2 capture by TETA/AMP aqueous and nonaqueous solutions proceeded by two different mechanisms. Polycarbamate...

Bright-green-emissive nitrogen-doped carbon dots as a nanoprobe for bifunctional sensing, its logic gate operation and cellular imaging

A fluorescent nanoprobe based on nitrogen-doped carbon dots (N-CDs) with green fluorescent emission have been fabricated through a facile one-step hydrothermal treatment using catechol and triethylene tetramine as precursors. The obtained N-CDs with excellent luminescent properties and superior biocompatibility have been applied for the development of a bifunctional sensor for the detection of Fe3+ and ascorbic acid (AA). Fe3+ that are tightly chelating the surface of N-CDs can induce fluorescence (FL) quenching of N-CDs through photo-induced electron transfer (PET). Meanwhile, the addition of AA serves to shelter the CDs effectively from being quenched by Fe3+ due to AA, as an antioxidant, enable easy-conversion of Fe3+ to reduced states (i.e. Fe3+ and Fe2+). The N-CDs are used as a facile and label-free “on-off-on” fluorescent nanoprobe for the determination of Fe3+ and AA with detection limits of 58.82nM and 0.236µM with the corresponding linear ranges of 25–200µM and 25–300µM, respectively. According to this phenomenon, an “AND” logic gate based on the novel N-CDs has been constructed. As-prepared N-CDs with negligible toxicity and perfect biocompatibility were expanded for cellular imaging and sensing Fe3+ and AA in living cell, which enlarges the application range of the N-CDs. Most importantly, the as-constructed fluorescent sensing system was successfully applied to detection of Fe3+ in tap water and the analyses of AA in fresh fruits with satisfactory results.

Application of Enriched Fraction of Seabuckthorn Leaf Extract as Antimicrobial Finish on Technical Textile

<p class="p1">Flavonoid-rich fraction (FRF) from Seabuckthorn leaves extract was prepared by acid hydrolysis process. Total flavonoid content of Seabuckthorn leaves extract and FRF estimated as rutin equivalent was found to be 116.98±3.06 and 277.14 ± 6.78 mg/g of extract/FRF respectively. Its major constituents myrcetin, quercetin, kaempferol and isorhamnetin, were determined by reverse phase high performance liquid chromatography (RP-HPLC). Aramid (NomexIIIA) fabric was treated with triethylene tetramine to increase the wicking height of the fabric for better uptake of FRF. Then, FRF was coated using citric acid as cross linking agent on to aramid fabric by pad-dry-cure method for improved wash durability. FRF coated fabric was characterised using Universal attenuated total internal reflection Fourier Transform Infrared spectroscopy. Effect of FRF coating on flammability property of coated fabric was estimated using flammability tester. There was no significant difference in the char length of the FRF coated fabric and control samples.<span class="Apple-converted-space"> </span></p><p class="p2">Antimicrobial activity of the FRF coated fabric was assessed by both qualitative (agar diffusion method; AATCC 147-2001) and quantitative (percentage reduction test; (AATCC 100-2001) methods using test organisms. The zone of inhibition by agar diffusion method for <em>E. coli </em>and <em>S. aureus </em>was found to be 12.4 mm and 16.7 mm respectively. Quantitative assessment by percentage reduction test showed a reduction percentage of 96.00% and 93.00% for <em>S. aureus </em>and <em>E</em>. <em>coli</em>, respectively. The results of the above study indicate FRF as a valuable ingredient for the development of antimicrobial textiles.</p>

The Layer of Kevlar Angle-interlock Woven Fabric Effect on the Tensile Properties of Composite Materials

This article is based on the structure of three-dimensional angle-interlock longitudinal.The 3-layer, 5-layer, 7-layer and 9-layer of angle-interlock 3D fabrics are woven on sample weaving machine respectively with the 1500D Kevlar fiber twist filament produced by United States DuPont. At the same time, Kevlar plain weave fabric is woven, and three, five, seven and nine layers’ fabric are to be compared. In the process of VARTM composite technology, epoxy resin is matrix material, acetone is diluent, triethylene tetramine is curing agent and the five different fabrics are the reinforced materials respectively. Finally, eight different three-dimensional woven fabric composites were prepared. In this paper, the tensile properties of eight kinds of three-dimensional woven fabric composites were tested respectively.Finally, it is concluded that the five-layer angle-interlock woven fabric prepared by Kevlar fiber shows the best tensile property.

Triethylene Tetramine Functionalized Magnetic Graphene Oxide Chitosan Composite with Superior Capacity for the Removal of Phosphate

A novel triethylene tetramine-functionalized magnetic graphene oxide chitosan composite material (TETA-MGO/CS) with a high adsorption capacity for the phosphate was prepared by chemical coprecipitation and subsequently modified by triethylene tetramine. TETA-MGO/CS was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, thermogravimetry, and Brunauer–Emmett–Teller analyses. The adsorption experiments of phosphate on TETA-MGO/CS were compared with MGO, MGO/CS, and TETA-MGO. Effects of pH, initial concentration of phosphate, adsorption time, and adsorption temperature were studied. The results indicated that the adsorption capacity of the four adsorbents were highly pH dependent and reached optimum at pH 3.0. Adsorption processes reached the equilibrium within 50 min. The adsorption data of the four adsorbents were well-fitted with the Langmuir isotherm. The maximum adsorption capacities of MGO, MGO/CS, TETA-MGO, and T...

Efficient synthesis of ethyl–piperazinyl quinolinyl-( E )-chalcone derivatives via Claisen–Schmidt reaction by using TiO 2 -BPTETSA catalyst

Abstract A new titanium nanomaterial based sulfonic acid catalyst was prepared and exhibited efficient catalytic activity for the synthesis of ( E )-3-(2-(4-ethylpiperazin-1-yl)quinolin-3-yl)-1phenylprop-2-en-1-one derivatives under solvent free conditions. Briefly the catalyst was synthesized by refluxing a mixture of nitric acid activated titanium dioxide, 3-mercaptochloropropyl and triethylene tetramine followed by filtration. This is a facile and environmentally benign method for preparation of the catalyst. The morphological properties of the catalyst was characterized by FT-IR, XRD, TEM, SEM, BET and Raman spectroscopy. The starting substrate 2-(4-ethylpiperazin-1-yl) quinoline-3-carbaldehyde ( 1 ) was synthesised from 2-chloro-3-formyl quinoline and an excess of 1-ethylpiperazine. The X-ray structure showed that the ethyl–piperazinyl N atom is attached to the aromatic ring and the dihedral angle between the mean planes of ethyl–piperazinyl ring atoms N (3)-C-(3)-N (2) has a geometric parameter of 117.9 (4) A thereby confirming the identity of the crystal structure. The one-pot Claisen–Schmidt reaction containing 1 and acetophenone derivatives were refluxed to produce chalcone derivative 3a-3n of yield 85–97%. They were characterised by IR, 1 H NMR, 13 C NMR and MS-TOF whilst 3 m included 90° DEPT, 135° DEPT, COSY, NOSEY, HSQCE and HMBC. High yield, simple methodology and short reaction time were some of the advantages of this methodology whilst a decrease of a mere 10% in catalytic activity, in five cycles, makes it cost effective for any possible large scale production. Furthermore ( E )-1-(1-hydroxynaphthalen-2-yl)-3-(2-(4-ethylpiperazin-1-yl)quinolin-3-yl) prop-2-en-1-one was used in molecular docking studies with bovine serum albumin protein binding was located in subdomain II A of BSA containing the amino acid residues ARG-209, LYS-212, ALA-213, VAL-216, PHE-226, ALA-229, SER-232, LYS-233 and THR239.

Microencapsulation of reactive amine by interfacially engineered epoxy microcapsules for smart applications

The most common approach for incorporation of extrinsic self-healing functionality relies on introducing healant-loaded micro-containers in the polymeric formulation. In this context, a healing system based on encapsulated epoxy resin and amine hardener appears to be one of the most economically viable solutions, in view of the chemical as well as mechanical compatibility with the matrix. Encapsulation of epoxy resins has been extensively studied while the high reactivity of the amine hardener renders its encapsulation rather difficult and has been attempted with only modest success. The purpose of the present work is to adopt an interfacial polymerization approach for the preparation of epoxy microcapsules encapsulating a reactive amine hardener (triethylene tetramine). The effects of experimental parameters, including reaction temperature, stirring speed and epoxy/amine concentration ratio on the microcapsule formation were investigated. A polymeric surfactant was used to stabilize the suspension to modulate the particle size distribution of the resultant microcapsules. The highest encapsulation efficiencies were obtained when the reaction medium was maintained at 70 °C under stirring (600 rpm) at epoxy/amine ratio of 10/3.2. The microcapsule dimensions and core content could be tailored, following this encapsulation approach of interfacial polymerisation. Under optimal conditions, spherical microcapsules with 100% yield and 12% core content were obtained.

Mesoporous silica as amine immobiliser for endowing healing functionality to epoxy resin

Abstract Feasibility of physical entrapment approach towards the immobilisation of amine hardener in mesoporous silica has been demonstrated for potential applications in the perspective of self-healing. A representative mesoporous silica (SBA-15) was synthesised using polymer-templated technique and employed as a substrate for immobilizing triethylene tetramine, a conventional epoxy hardener. Polymeric composites containing microencapsulated epoxy microcapsules and amine loaded SBA-15 were prepared by room temperature curing. The autocatalytic nature associated with the curing of epoxy remained unaltered due to introduction of either SBA-15 or epoxy loaded microcapsules, as confirmed by calorimetric studies. Healing efficiency, as quantified in terms of the ratio of impact strength before and after healing, was found to increase proportionally with increasing loading of healing additives in the formulation, with complete healing (100%) being exhibited at 20% microcapsule loading.