Polyamine Adduct Research Articles

Mass Spectrometry of Putrescine, Spermidine, and Spermine Covalently Attached to Francisella tularensis Universal Stress Protein and Bovine Albumin.

Bacterial and mammalian cells are rich in putrescine, spermidine, and spermine. Polyamines are required for optimum fitness, but the biological function of these small aliphatic compounds has only been partially revealed. Known functions of polyamines include interaction with nucleic acids that alters gene expression and with proteins that modulate activity. Although polyamines can be incorporated into proteins, very few naturally occurring polyaminated proteins have been identified, which is due in part to the difficulty in detecting these adducts. In the current study, bovine albumin and the recombinant universal stress protein from Francisella tularensis were used as models for mass spectrometry analysis of polyaminated proteins. The proteins were covalently bound to putrescine, spermidine, or spermine by the action of carbodiimide or microbial transglutaminase. Tryptic peptides, subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS), were identified using Protein Prospector software. We describe the search parameters for identifying polyaminated peptides and show MS/MS spectra for adducts with putrescine, spermidine, and spermine. Manual evaluation led us to recognize signature ions for polyamine adducts on aspartate, glutamate, and glutamine, as well as neutral loss from putrescine, spermidine, and spermine during the fragmentation process. Mechanisms for the formation of signature ions and neutral loss are presented. Manual evaluation identified a false-positive adduct that had formed during trypsinolysis and resulted in peptide sequence rearrangement. Another false positive initially appeared to be a 71 kDa putrescine adduct on a cysteine residue. However, it was an acrylamide adduct on cysteine for a sample extracted from a polyacrylamide gel. The information presented in this report provides guidance and serves as a model for identifying naturally occurring polyaminated proteins.

Polythiourethane microcapsules as novel self-healing systems for epoxy coatings

A novel group of microcapsule-based self-healing systems for epoxy coatings was developed. Microcapsules with polythiourethane shell wall were synthesized via interfacial polymerization from selected diisocyanates and thiols and dispersed in epoxy matrix. The obtained composites were tested for their self-healing efficiency using three-point bending test (TPBT) and scratch test. Two sets of each composite samples as well as reference (neat diglycidyl ether of bisphenol A epoxy with polyamine adduct hardener) were tested with TPBT using two methods. Standard method according to ISO 178 was applied for the first set and custom method with pre-bending with 20 N force and standard TPBT after 24 h of self-healing—for the second set. Pre-bending was applied to obtain microcracks (without sample cracking) for internal self-healing process occurrence. Scratch test allowed to evaluate self-healing efficiency at composite surface and chemical resistance of samples. FT-IR spectroscopy was conducted to confirm occurrence of self-healing process based on polyurethane secondary network forming.

Influence of cross-linking agents and curing condition on the performance of epoxy coating

Purpose The performance of epoxy coating on metal substrate at low temperature and high humidity application has adverse effect on cure rate, film properties and adhesion. In recent years, several advanced amine cross-linking agents having superior curing ability at low temperature application environment have been introduced. The aim of this paper is to study the properties of epoxy-based coating cured with different cross-linking agents designed for low temperature application at different environmental conditions. Design/methodology/approach Series of cross linking agents such as modified cycloaliphatic amine (H1), polyamine adduct (H2), modified aliphatic ketamine (H3), phenalkamine (H4) and phenalkamide (H5) have been studied to evaluate their performance in epoxy compositions when cured at four environmental conditions, i.e. at ambient and sub-ambient temperatures with 60 and 90 per cent relative humidity, respectively. The effect of curing conditions was investigated by evaluating different physico-mechanical properties. Dynamic mechanical analyser technique was used to determine glass transition temperature (Tg) and cross-link density (ρ) of coatings. Anticorrosive properties of coatings also have been studied by electrochemical impedance spectroscopy. Findings The outcome of this study is expected to generate new insight into the curing behaviour of epoxy coating using different cross-linking agents which are recommended for low temperature application. Optimum physico-mechanical and corrosion resistance properties have been obtained by phenalkamine curing agent at low temperature and high humidity condition. Practical implications This study is an experimental approach to select the better cross-linking agent for low temperature application. Different test conditions were measured for understanding the performance of epoxy coating cured at different environmental condition. Originality/value The understanding reaction mechanism of the epoxy resin with cross-linking agent at different environmental condition is the great challenge and is hardly investigated in the literature. Therefore, in this research, the influence of climatic conditions and type of cross-linking agents on curing behaviour of epoxy-based coating was investigated.

Polypyrrole in water borne epoxy coating

Purpose – The paper aims to discuss the evaluation of anti-corrosive efficiency of conducting polymer, polypyrrole in water borne epoxy-polyamine coatings. Design/methodology/approach – Polypyrrole (PPy) is synthesised by chemical oxidative polymerisation. The synthesised PPy is characterised by employing FT-IR, XRD, SEM and EDX analysis. The coatings are formulated using water borne epoxy cross-linked with aliphatic polyamine adduct and the effect of PPy on corrosion prevention is studied. PPy was used as anti-corrosive pigment in concentration varying from 1 to 5 wt.%. In addition to anti-corrosive property; mechanical properties, chemical resistance and weathering properties of the coatings containing PPy are studied, thereby obtaining a wholesome data about the quality and performance of these coatings. Findings – The result obtained through various tests showed that the coating with 1 and 2% PPy exhibited excellent weathering resistance, mechanical properties and improved chemical resistance. Higher percentage loading of PPy (beyond 3 per cent) proves to be disastrous, as extended percolation networks are formed which results in rapid intense corrosion leading to fast coating breakdown. Research limitations/implications – The anti-corrosion property of the coating can be tested by means of atmospheric exposure such as Florida test which produces a real time evaluation of the anti-corrosive nature of the coating at natural condition rather than accelerated weathering, thereby providing more reliable performance data for intended application purpose. Practical implications – The results find application in anti-corrosive/performance paints for industrial application. Originality/value – This research paper presents the results of anti-corrosion behaviour of PPy in water borne epoxy-polyamide coating. Based on this result, a highly effective anti-corrosive coating can be formulated by the addition of small percentage of PPy in combination with other conventional pigments, thereby enhancing corrosion protection. But care must be taken so as to avoid formation of extended percolation network of PPy which leads to rapid coating breakdown.

On the Solution Behaviour of Benzyllithium⋅(−)-Sparteine Adducts and Related Lithium Organyls - A Case Study on Applying7Li,15N{1H} HMQC and Further NMR Methods, Including Some Investigation into Asymmetric Synthesis

2D (7)Li,(15)N heteronuclear shift correlation through scalar coupling has successfully been applied to several lithium organyls consisting of polydentate N ligands such as N,N,N',N'-tetramethylethylenediamine (tmeda), N,N,N',N',N''-pentamethyldiethylentriamine (pmdta) and (-)-sparteine. Structural insights on the conformation of benzyllithium·pmdta (5) in a toluene solution and the strength of ion pairing in combination with PGSE NMR measurements, (1)H,(1)H-NOESY and (1)H,(7)Li-HOESY experiments are presented. By studying in detail the formation of 5 in solution, a transient species has been observed for the first time and assigned to a pre-complex of nBuLi and pmdta. In addition, the solution behaviour of the complex formed between benzyllithium and (-)-sparteine (8) has been studied by PGSE and multinuclear NMR spectroscopy. The straightforward synthesis and first applications in asymmetric lithiations are also reported, which show that the new system benzyllithium·(-)-sparteine (8) provide poorer enantioselective induction than the classical nBuLi·(-)-sparteine (6). The results were supported by deprotonation experiments confirming that the formation of 8 relies on two relevant factors, namely temperature and lithiating reagent. The existence of 8 may thus interfere with the asymmetric induction when the system nBuLi· (-)-sparteine is used in the enantioselective deprotonations of N-Boc-N-(p-methoxyphenyl)-benzylamine conducted in toluene.

Fast Fourier Transform IR Characterization of Epoxy GY Systems Crosslinked with Aliphatic and Cycloaliphatic EH Polyamine Adducts

The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm−1, as well as at about 3,056 cm−1, was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin.

Anticorrosive properties of the epoxy–cardanol resin based paints

An epoxy–cardanol resin was developed using epichlorohydrin, bisphenol-A and cardanol. On evaluation it was found that epoxy–cardanol resin exhibits better properties as compared to epoxy resin in terms of increase in tensile strength, elongation, bond with steel and lowering of water vapour transmission of the film. The improvement in these properties indicated that the paints based on modified resin would be more durable than the epoxy based paints. Accordingly, paints were formulated using the developed resin and their performance were compared with their counterparts made with unmodified epoxy resin. Zinc powder, zinc phosphate, micaceous iron oxide and synthetic iron oxide were used as pigments along with fillers, additives and an aromatic polyamine adduct hardener. For both types of paints similar doses of pigments and additives were used. Physico-mechanical properties, chemical resistance and corrosion protection efficiency of the formulated paints were determined. It was found that the anticorrosive properties of epoxy–cardanol resin based paints are superior to that of the paints formulated with the unmodified epoxy resin. Micaceous iron oxide based paints in epoxy–cardanol resin showed the best performance followed by zinc phosphate based paints. It is concluded that the developed resin is a better binder media for the formulation of paints.

Thermal and Morphological Properties of Silicone‐Polyurethane‐Epoxy Intercrosslinked Matrix Materials

Three different types of epoxy resins based on an unmodified epoxy (diglycidyl ether of bisphenol‐A), polyurethane (PU) modified epoxy and silicone modified polyurethane‐epoxy matrices were developed. Epoxy resin was modified with PU prepolymer and hydroxyl terminated poly (dimethyl siloxane), also referred to as ‘silicones’ using a silane crosslinking agent and tin catalyst. Aromatic polyamine adduct (A), diethylenetriamine (B) and polyamidoamine (C) were used as epoxy curatives. The formation of intercrosslinked network was confirmed using Fourier transform‐infrared (FT‐IR) spectra and viscosity data. Thermo gravimetric analysis revealed reduced thermal stability for PU (10 wt%) modified epoxy, whereas the incorporation of silicone (10 wt%) into PU modified epoxy matrix improved their thermal properties. The morphology of silicone modified PU‐epoxy was also studied by scanning electron microscopy (SEM).

Mechanical and Electrical Studies of Silicone Modified Polyurethane–Epoxy Intercrosslinked Networks

A series of intercrosslinked networks (ICNs) based on silicone modified polyurethane (PU)–epoxy resins were developed. In this study, epoxy resin (diglycidyl ether of bisphenol-A) was modified with PU prepolymer and hydroxyl-terminated polydimethylsiloxane (HTPDMS) using γ-aminopropyl triethoxysilane (γ-APS) as silane cross linker and dibutyltindilaurate (DBTL) as catalyst to form ICNs. Aromatic polyamine adduct (A), diethylenetriamine (B) and polyamidoamine (C) were used as epoxy curatives. The final products were obtained in the form of tough films. Changes in chemical structure during ICN formation, mechanical and electrical properties were investigated using FT-IR spectra, tensile, impact and dielectric testing. The mechanical properties were enhanced with incorporation of PU (10 wt %) and silicone (10 wt %) due to the toughening of brittle epoxy matrices. Electrical properties showed a marginally decreasing trend with the incorporation of PU (0–20 wt %) influenced by the polar urethane linkages whereas silicone incorporation (10 wt %) showed an enhancement due to the presence of inorganic –Si–O–Si– linkage. Among the systems studied, the silicone (10 wt %) modified PU (10 wt %)–epoxy cured with “A” exhibited excellent mechanical and electrical characteristics and can be used as coatings and composites for industrial, electrical and marine components.

Mechanical and thermal studies of intercross-linked networks based on siliconized polyurethane-epoxy/unsaturated polyester coatings

Two different intercross-linked networks (ICN) of siliconized polyurethane-epoxy/unsaturated polyester (UP) coatings were developed. Epoxy and UP resins were modified with polyurethane (PU) prepolymer and hydroxyl terminated polydimethylsiloxane (HTPDMS) using γ-aminopropyl triethoxysilane (γ-APS) and vinyltriethoxysilane (VTES) as silane cross-linkers and dibutyltindilaurate (DBTL) as catalyst. Aromatic polyamine adduct (A) and aliphatic amine (B) were used as curatives for epoxy and methyl isobutyl ketone peroxide (C) as curative for UP resin. The coating materials were obtained in the form of tough films and characterized for their mechanical properties such as tensile strength and impact test as per ASTM methods. The thermal stability of the ICN coatings was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and compared with unmodified epoxy/UP systems. Mechanical properties were enhanced with incorporation of PU (10 wt.%) and silicone (10 wt.%) due to the toughening of brittle epoxy and UP systems. The introduction of PU into unmodified epoxy/UP coating systems reduces the thermal stability due to the presence of thermally weak urethane linkages whereas, the incorporation of 10 wt.% silicone into PU modified epoxy/UP systems improves their thermal stability due to the partial ionic nature, high bond energy and thermal stability of –Si–O–Si– linkage.

Thermal properties of siliconized epoxy interpenetrating coatings

This work involves the development of a novel siliconized epoxy interpenetrating coating system using epoxy resin as base, hydroxyl-terminated polydimethylsiloxane (HTPDMS) as modifier, γ-aminopropyltriethoxysilane (γ-APS) as crosslinking agent and dibutyltindilaurate (DBTDL) as catalyst. Polyamidoamine and aromatic polyamine adduct were used as curing agents for the above coating systems. The thermal behaviour, glass transition temperature ( T g) and morphological characteristics of unmodified epoxy and siliconized epoxy coating systems cured by polyamidoamine (B) and aromatic polyamine adduct (D) were studied using thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy, respectively, and the results are discussed. From the study, it is observed that the thermal stability of epoxy coating systems is enhanced when siloxane is incorporated to them. There is a slight decrease in the glass transition temperature observed for silicone-modified epoxy coatings and SEM analyses reveal that siliconized epoxy coating systems show heterogeneous morphology.

An experiment on apoptosis induced by polyamine adducts produced in the presence of serum amine oxidase

A two-session experiment is proposed to train students with an easy, economic and educative procedure to detect the typical DNA ladder produced in many apoptotic events. The procedure is accurate enough to provide an easy way to compare degrees of damage in DNA caused by different treatments.

An experiment on apoptosis induced by polyamine adducts produced in the presence of serum amine oxidase

A two-session experiment is proposed to train students with an easy, economic and educative procedure to detect the typical DNA ladder produced in many apoptotic events. The procedure is accurate enough to provide an easy way to compare degrees of damage in DNA caused by different treatments.

A novel technique for visualizing the intracellular localization and distribution of transported polyamines in cultured pulmonary artery smooth muscle cells

The use of a combination of monofluorescein adducts of spermidine (FL-SPD) and spermine (FL-SPM) with confocal laser scanning microscopy (CLSM) provides a useful means for monitoring the fate and time-dependent changes in the distribution of transported polyamines within living cells. Polyamine-fluorescein adducts were synthesized from fluorescein isothiocyanate and the appropriate polyamine. Monofluorescein polyamine adducts (ratio 1:1) were isolated using thin layer chromatography, and the structure and molecular weight of the monofluorescein polyamine adducts were confirmed using NMR and mass spectroscopy, respectively. The covalent linkage of the fluorescent adduct moiety to SPD and SPM did not influence their rate of uptake by bovine pulmonary artery smooth muscle cells (PASMC). Similar to 14C-SPD and 14C-SPM, the rate of uptake of 14C-FL-SPD and 14C-FL-SPM in PASMC was temperature-dependent. Treatment for 24 h with difluoromethylornithine (DFMO), a selective blocker of the enzyme ornithine decarboxylase and an inducer of the polyamine transport system, significantly increased the cellular uptake of 14C-FL-SPD and 14C-FL-SPM compared to that of control cells. When compared to control cells, treatment of PASMC with the pyrrolizidine alkaloid monocrotaline for 24 h also significantly increased the cellular uptake of 14C-FL-SPD and 14C-FL-SPM. On the other hand, 24 h treatment of PASMC with a polymer of SPM, a selective blocker of the polyamine transport system, or with free spermine, markedly reduced the cellular accumulation of 14C-FL-SPD and 14C-FL-SPM. After a 20-min treatment of PASMC with FL-SPD or FL-SPM, CLSM revealed that adduct fluorescence was localized in the cytoplasm of living cells. Treatment with DFMO increased the cytoplasmic accumulation of both FL-SPD and FL-SPM. In addition, the fluorescence observed in the cytoplasm of chinese hamster ovary cells (CHO) was significantly higher than that detected in the cytoplasm of their polyamine transport deficient variants (CHOMGBG). The results of this study provide the first evidence of the utility of a novel method for visualizing the uptake, distribution, and cellular localization of transported polyamines in viable cultured mammalian cells.

X-ray crystal structures and thermal behaviour of two volatile bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)barium-(azapolyether) complexes

Two novel Ba(hfac) 2 · (azapolyether) [hfac = 1,1,1,5,5-hexafluoropentane-2,4-dionato] adducts have been synthesized and characterized by single crystal X-ray crystallography, differential scanning calorimetry and spectroscopic methods. Compound 1 contains the macrocyclic ligand 1-aza-4,7,10,13,16-pentaoxacyclooctadecane [1-aza-18-crown-6], while compound 2 contains the acyclic ligand 8-aza-2,5,11,14-tetraoxapentadecane [8-azatetraglyme]. In both compounds the azapolyether ligands coordinate a central barium atom in a meridional fashion, with the hfac ligands on opposite sides of the neutral ligand plane. The basic coordination geometries of complexes 1 and 2 are thus analogous to those in most of the barium β-diketonate polyether and polyamine adducts structurally characterized in earlier work. However, closer examination of their crystal and molecular structures reveals several interesting features, including markedly different geometries for the two non-equivalent molecules in the unit cell of 1, and also relatively long hfac oxygen to barium bond lengths in this complex. Both 1 and 2 sublime at ca 135°C and 0.05 Torr, with 2 showing much higher volatility. 1 melts with decomposition at ca 240°C, while 2 undergoes melting with minimal decomposition at ca 170°C. Both compounds have endothermic solid state transitions between 25°C and their melting temperatures. The kinetically slow solid state transition of 1 has been studied in detail, demonstrating its phenomenological similarity to a previously studied process in Ba(hfac) 2 · (18-crown-6). Combined with earlier results, the current work suggests that the solid state transitions of 1 and Ba(hfac) 2 · (18-crown-6) may involve isomerization reactions in which the barium coordination geometry changes fundamentally.

Iodopropionic acid staining of waterborne epoxy films

The examination of polymer material by transmission electron microscopy (TEM) often relies on staining in order to improve contrast or preferentially stain a polymer phase. Stains such as osmium tetroxide for unsaturated polymers and ruthenium tetroxide for unsaturated as well as certain saturated polymers have been used quite extensively. A new stain, 3-iodopropionic acid, has been found to be very useful to stain preferentially the amine rich domains in waterborne epoxy films.An epoxy dispersion (epoxy equivalent weight, EEW=625) and a polyamine adduct curing agent (AHEW=163) at a 1.5:1 stoichiometry was prepared. The volatile organic content (VOC) was 2.6 lb./gal., and the solvent blend was 90.6% propoxy ethanol and 9.4% Aromatic 150. The particles size of the starting dispersion was obtained by TEM and disk centrifuge and found to be approximately 500 nm. Films (approximately 1.2 mil dry film thickness[DFT]) were cast on a partially fluorinated polyethylene film, 0.5, 2, 4, and 8 hours after hand mixing and cured for two or more weeks at 25° C and 50% relative humidity.

Epoxy-poly(2-ethylhexyl acrylate) interpenetrating polymer networks morphology and mechanical and thermal properties

Full and semi-IPNs of Poly(2-ethylhexyl acrylate), PEHA & crosslinked epoxy homopolymer were prepared and characterized by measurements of mechanical, thermal and morphological properties. Aromatic polyamine adducts and ethylene glycol dimethacrylate were used as the cross-linker for epoxy and comonomer/cross-linker for 2-ethyl hexyl acrylate monomer. Effects of changes of blend ratio on the properties were examined. Semi-IPNs were characterized by higher tensile strength and modulus than the corresponding full IPNs. Both semi- and full IPNs were characterized by broadening of transitions in their respective DSC curves while the weight retention in the thermal decomposition of the IPNs and pseudo-IPNs was higher than the epoxy homopolymer network. Phase separated rubber domains of various sizes are presumed to be responsible for the increased toughness of poly(2-ethyl hexyl acrylate)-modified epoxy which is substantiated by SEM micrographs.

Mononuclear Barium Diketonate Polyamine Adducts. Synthesis, Structures, and Use in MOCVD of Barium Titanate

Mononuclear barium {beta}-diketonate Lewis base adducts have been synthesized by reaction of Ba(thd){sub 2} (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) with polyamines 1,1,4,7,7-pentamethyldiethylenetriamine (pmdt) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (hmtt). The adducts [Ba(thd){sub 2}(pmdt)] (I) and [Ba(thd){sub 2}(hmtt)] (II) have been characterized by NMR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound I crystallizes in the space group P2{sub 1}/c with a = 10.577(3) {angstrom}, b = 23.547(7) {angstrom}, c = 15.963(5) {angstrom}, {beta} = 105.21(2){degrees}, and Z = 4. Compound II crystallizes in the space group P2{sub 1}/c with a = 10.833(6) {angstrom}, b = 20.442(12) {angstrom}, c = 19.404(9) {angstrom}, {beta} = 104.35(4){degrees}, and Z = 4. The adducts are seven- and eight-coordinate, respectively, with all nitrogen atoms of the polyamine bound to a single barium center. Compound I has been used for thin-film growth of BaTiO{sub 3} which has revealed that, compared to Ba(thd){sub 2}(tetraglyme), the polyamine adduct allows a larger temperature window for effective vapor transport. 10 refs., 2 figs., 2 tabs.

Epoxy/poly(methyl methacrylate) interpenetrating polymer networks—morphology, mechanical and thermal properties

AbstractFull and semi‐IPNs were prepared from epoxy and poly methyl methacrylate (PMMA), by the sequential mode of synthesis and were characterized by measurements of ultimate tensile strength (UTS), elongation at break, modulus, and toughness. Aromatic polyamine adducts and ethylene glycol dimethacrylate were used as the crosslinkers for epoxy and comonomer/crosslinker for methyl methacrylate monomer, respectively. Higher UTS and modulus of the semi‐IPNs over full IPNs were attributed to the higher probability of interpenetration. The weight retention in the thermal decomposition of the IPNs and semi‐IPNs were higher than the epoxy homopolymer. This enhancement was presumably related to the presence of the unzipped methyl methacrylate monomer which acted as radical scavangers in the epoxy degradation. © 1994 John Wiley & Sons, Inc.

Advances in Precursor Development for CVD of Bariumcontaining Materials

AbstractBarium titanate and barium-strontium titanate (BST) are high dielectric materials, likely to replace state-of-the-art capacitor materials for memory applications. Chemical Vapor Deposition (CVD) of these materials has been hampered, particularly by the lack of suitable precursors for barium. Although attempts to make volatile metal-organic barium compounds have met with some progress, a suitably stable, volatile barium source is still in demand. This paper will highlight recent developments at ATM, including syntheses and structures of polyamine and glycol ether adducts which have been designed to limit aggregation of barium diketonates, and stabilize the adducts with respect to ligand dissociation.