Synthesis,characterization and properties of a castor oil modified biodegradable poly(ester amide) resin

A biodegradable poly(ester amide) resin was synthesized from N,N-bis(2-hydroxy ethyl) fatty amide of castor oil with maleic anhydride, phthalic anhydride and isophthalic acid (100:30:35:35 mole ratio) by the polycondensation process. The fatty amide of the oil was obtained for the first time with 95% yield. The chemical structure of the synthesized resin was characterized by spectroscopic techniques like FTIR, ¹H NMR and ¹³C NMR. Various physical properties such as acid value, saponification value, iodine value, specific gravity and viscosity of the resin were also determined. Further the rheological behavior, studied in the steady shear mode showed shear thinning behavior of the resin. The epoxy cured poly(ester amide) thermoset using poly(amido amine) hardener exhibited better properties than with the cycloaliphatic amine hardener cured system. TGA studies also revealed higher thermal stability of the former system than the latter. In vitro-biodegradation study of the poly(ester amide) thermoset using Pseudomonas aeruginosa and Bacillus subtilus bacteria revealed superior biodegradability of the thermoset using the former bacterial strain. Excellent chemical resistance against various chemical media including alkali was observed for epoxy-poly(amido amine) cured poly(ester amide) resin over epoxy-cycloaliphatic amine one. The epoxy-poly(amido amine) cured poly(ester amide) thermoset thus has the potential to be used as surface coating material.     

Functional group efficiency in adhesion between polyethylene and aluminum

The effect of different functional groups on the adhesion between polyethylene and aluminum has been studied. Poly(ethylene-co-butyl acrylate) (EBA) and poly(ethylene-co-vinyl acetate) (EVA) were used as such and provided polyethylene surfaces with two different kinds of ester groups, butyl ester and acetate, respectively. By alkaline hydrolysis in an organic solvent the surface functionality could be changed to carboxylate and hydroxyl, respectively. Finally, acid washing converted the carboxylate groups into carboxylic acid. The effect of the surface treatments were followed by reflection IR. T-peel tests of laminates made of the original, as well as the surface-treated polymers, and aluminum allowed an evaluation of the specific contribution to the adhesion for the groups in question. The peel strength increased linearily with the bulk concentration of comonomer in the original EBA and EVA samples. The values increased from about 100 N/m for polyethylene up to 2500 N/m in the case of 3.7 mol % of carboxylic acid. The efficiency of the investigated functional groups increased in the following order: ? H<? O? CO? CH₃ <? CO? O? C₄H₉ <? COONa～? OH<? COOH.     

Synthesis and characterization of novel bifunctional mesoporous silica catalyst and its scope for one-pot deacetalization–knoevenagel reaction

Bifunctional (both sulfonic and amine functionalized) mesoporous silica catalysts were prepared by hydrothermal method. (3-[2-(2-amino ethyl amino) ethyl amino] propyl trimethoxysilane) and (3-mercaptopropyl) trimethoxysilane respectively were used as amine and sulfonic sources. The synthesised bifunctional materials were fully characterized by BET, P-XRD, ²⁹Si CPMAS-NMR, FTIR, XPS and SEM spectral analysis. FTIR and NMR results endorse the successful grafting of organic amines and sulfonic group by surface silanol of silica. The presence of of N and S groups in the catalyst material was confirmed by the XPS spectra. Catalytic activity of the bifunctional material was tested for one-pot deacetalization–knoevenagel reaction, which gave excellent yield (95 %). Catalyst is reusable with little loss of activity up to 4 runs (<6 %).     

Biomass grafted with polyamic acid for enhancement of cadmium(II) and lead(II) biosorption

In this study, a simple method was used to prepare modified biomass to improve its adsorption capacity for Cd²⁺ and Pb²⁺. The modified biomass of baker’s yeast was obtained by grafting polyamic acid, which was prepared via the reaction of pyromellitic dianhydride (PMDA) and lysine, onto the surface of glutaraldehyde-pretreated biomass at 50 °C for 3 h. The presence of polyamic acid on the biomass surface was verified by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), the morphologies of the biomass before and after modification were observed by microscope. Due to the high density of the carboxyl and amide groups on the biomass surface, the uptake for Cd²⁺ and Pb²⁺ showed a significant increase. According to Langmuir adsorption isotherm, the maximum uptake for Cd²⁺ and Pb²⁺ were 95.2 and 204.5 mg g⁻¹, which were 15- and 11-fold for that obtained on the uncontaminated biomass. The kinetics for Cd²⁺ and Pb²⁺ adsorption followed the pseudo-second-order model. The results of FTIR and XPS revealed that carboxyl, amide, and hydroxyl groups on the biomass surface were involved in the adsorption of Cd²⁺ and Pb²⁺.     

Synthesis and solution properties of a new pH-responsive polymer containing amino acid residues

The amine salt, N,N-diallyl-N-carboethoxymethylammonium chloride was cyclopolymerized in water using ammonium persulfate as an initiator to afford a cationic polyelectrolyte which on acidic hydrolysis of the pendant ester groups gave the corresponding cationic acid salt (CAS). The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB). The solution properties of the APE having two basic functionalities were investigated in detail by potentiometric and viscometric techniques. Basicity constants of the amine as well as the carboxylate groups in APE are ‘apparent’ and as such follow the modified Henderson-Hasselbalch equation; as the degree of protonation (α) of the whole macromolecule increases, the protonation of the amine nitrogens and carboxylate groups becomes increasingly more difficult and easier, respectively. While the APE, PB and CAS were found to be soluble in salt-free water, the corresponding PB and CAS of the SO₂ copolymers of the amine salt 1 were found to be insoluble in water.     

Synthesis and in situ transformation of poly(oxybutylene)amides by butoxylation

A family of gasoline detergents was prepared by a two-step process—(1) preparation of amide initiators by reacting hydrophilic amines with ethyl acetate at high temperature; (2) consecutive butoxylation of the initiators with 1,2-epoxybutane (BO) to obtain oil-soluble products. The process led to the preparation of amide-initiated butoxylates, which were characterized by FTIR, NMR, and amine titration. During the butoxylation, it was found that the unexpected ester by-products were generated via an amide/ester exchange. The reaction profile was studied. The amide/ester exchange reaction, characterized by IR absorption of amide (1650 cm⁻¹) vs. ester (1735 cm⁻¹), reached equilibrium during the process of butoxylation to 1600 M_w. Steric hindrance of the amide structures is an important factor controlling the formation of these ester byproducts. Selective hydrolysis to remove the ester by-products is necessary to render the final product with an improved engine performance of octane requirement. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 435–445, 2001     

Reduction of solubilized multi-walled carbon nanotubes

In this paper, the chemical reduction of solubilized multi-walled carbon nanotubes by LiAlH₄ was investigated. The amide groups on the nanotubes could be reduced to hydroxyl groups, which was confirmed by FTIR and XPS studies. The Raman spectroscopic investigation showed that the morphology of the nanotubes did not change after the reduction.     

Novel amino acid-based polymers for pharmaceutical applications

Summary Entirely amino acid-based polymers were prepared by side-chain attachment to polysuccinimide derived from the thermal polycondensation of aspartic acid. Following deprotonation of various amino acid ester hydrochlorides by a secondary amine, the restored primary amino groups initiated the ring-opening of succinimide to form amide bonds. ¹H and ¹³C NMR measurements revealed that the mole fraction of the introduced amino acid side chains could be controlled by the reaction time, while no hydrolysis of methyl ester groups was observed. The synthesized polymers contain exclusively amino acids, which makes them promising candidates as base materials of controlled drug delivery systems.     

Functionalization of the Unactivated Carbon-Hydrogen Bond Via Ozonation

Three alkanes and two ethers were oxidized with ozone in dichloromethane solution or in aqueous pH 3 suspension. Cyclodecane and cyclododecane were converted into the corresponding cycloalkanones. n-decane was converted into a mixture of isomeric n-decanones and carboxylic acids. An ester was formed from the ethers. Hence, one of the methylene groups of these substrates is generally converted into a carbonyl group. Some of these reactions have preparative value.     

Poly(ethylene glycol) grafted polystyrene dendrimer resins: Novel class of supports for solid phase peptide synthesis

Poly(propyleneglycol)dimethacrylate cross-linked support using monomers Styrene and 4-chloromethyl styrene (PS-PPGDMA-VBC resin) was prepared by suspension polymerization method. Dendritic templates were synthesized from Schiff base and trimesic acid molecules and assembled independently on PS-PPGDMA-VBC support to the second generation. N,N-bischloro ethyl amine dendrimer was generated from Schiff base units and introduced to the chloromethyl groups uniquely through secondary amine. It was followed by acidolytic cleavage, diazotization and thionyl chloride reactions leading to first generation dendrimer. O-benzyl ether dendrimer was created using 1,3,5-tris(hydroxyl methyl)benzene unit which was produced by the LiAlH₄ reduction of carbonyl groups of trimesic acid molecule. The hydroxyl methyl groups formed were converted to chloro methyl groups by adding thionyl chloride that leads to first generation dendrimer. Similar synthetic routes were followed to produce second generation dendrimers too. Poly(ethylene glycol), M_n ≈ 1500) has been grafted to chlorine termini of both dendrimers and used to check various physical and chemical properties of different peptide synthetic conditions. Reactions were qualitatively analyzed by FTIR, ¹³C NMR, SEM and quantitatively analyzed by UV measurements and CHN analysis. Classically difficult ACP sequence was synthesized on both PEGylated dendrimer supports and compared to Tenta Gel. Biologically significant disulfide bonded endothelin class of peptides were also synthesized using novel supports using various literature reported methods.     

Zinc oxide surface functionalization and related effects on corrosion resistance of titanium implants

Important clinical concerns in orthopedics and dental implantology are associated with a significant release of titanium (Ti) metal ions and debris due to the low corrosion resistance of this material. Chemical modifications on Ti surfaces have been performed in order to minimize effects of corrosion. In this contribution, zinc oxide (ZnO) thin films were deposited onto Ti surfaces and functionalized with four different organic bifunctional molecules in order to increase the corrosion resistance. SEM and XPS indicated the formation of nanostructured ZnO thin film with hydroxyl groups available for covalent functionalization. The adhesion mechanism analyzed by XPS suggest that the attachment on ZnO occurs by carboxylic acid, silane, thiol and hydroxyl groups for 4-aminophenylpropionic acid (APPA), 3-aminopropyltrimetoxysilane (APTMS), 3-mercaptopropionic acid (MPA), and polyethylene glycol (PEG) molecules. Electrochemical analysis for the functionalized ZnO specimens with APPA showed noble open circuit potentials (?0.2 V) and significant decrease in the corrosion current density (5.3 × 10^?7 A/cm²) when compared to the values obtained for pristine Ti (?0.56 V and 2.3 × 10^?6 A/cm²), indicating a promising material for applications in biomedical fields.     

Development and mechanism characterization of high performance soy-based bio-adhesives

The techniques for denaturing defatted soy flour (DSF) for the production of high performance soy-based bio-adhesives (SBA) have been developed. The developed soy based products from various stages of process were characterized using FTIR and XPS to examine the denaturing mechanisms. The results from the orthogonal statistics [L₉(3⁴)] showed that the optimized ratio of DSF:H₂O was 2:8 by weight and the best combination of acid:salt:alkali was 2.38:0.002:7.98% total mass of DSF and H₂O. The FTIR and XPS spectra illustrated the change of chemical groups and conversion of the protonized products: the amide link hydrolysis and decarboxylation have taken place when DSF was denaturized by acid and salt with the active groups, –NH₂, –COOH and –OH, increased. The alkali modification caused some aminolysis with the active groups increased further. Curing SBA made amide links reestablished and hence caused amination, resulting in the improvement of cross-linkage of soy-protein and hence water-resistance.     

Surface modification of bioceramics by grafting of tailored allyl phosphonic acid

Abstract

A new route to interfacial bonding between ceramic and matrix in biocomposites is identified. A tailored allyl phosphonic acid is used as a coupling agent bound to the surface of a bioceramic to form a 'grafted' calcium phosphate (CAP). The allyl phosphonic acid coupling agent is synthesised by reaction of allyl halide and trialkyl phosphite. Successful synthesis was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). The allyl phosphonic acid was incorporated onto calcium phosphate using a wet chemical coprecipitation synthesis route. The resulting 'grafted' CAP was characterised using FTIR coupled with photoacoustic sampling, and Fourier transform Raman spectroscopy (FTR). The spectroscopic data suggest an interaction between the allyl phosphonic acid and calcium phosphate resulting from observed reductions in intensity of the hydroxyl (3570 cm^?1) and phosphate ν ₃ (1030 cm^?1) peaks. The continued presence of C=C functionality on the surface of the grafted CAP was indicated by FTIR and FTR spectra (peaks at 1650 and 1635 cm^?1 respectively) and confirmed by X-ray photoelectron spectroscopy (XPS). On the basis of these results, it is concluded that grafted CAP may be used to produce a chemically bonded composite with superior mechanical properties.     

Synthesis and characterization of new thermally stable aromatic copoly(ester–amide)s from diester‐dicarboxylic acids

Two new aromatic diester‐dicarboxylic acids containing furan rings, namely, benzofuro[2,3‐b]benzofuran‐2,9‐dicarboxyl‐bis‐pyridyl ester‐4,4′‐dicarboxylic acid and benzofuro[2,3‐b]benzofuran‐2,9‐dicarboxyl‐bis‐phenyl ester‐4,4′‐dicarboxylic acid were synthesized by the reaction of benzofuro[2,3‐b]benzofuran‐2,9‐dicarbonyl chloride with 6‐hydroxynicotinic acid and 4‐hydroxybenzoic acid, respectively. These monomers were converted to aromatic copoly(ester–amide)s by reaction with various aromatic diamines via direct polycondensation. Polymers were characterized by FTIR and ¹H NMR spectroscopy, thermogravimetry, viscosity and solubility tests. The inherent viscosity of the polymers was in the range 0.23–0.46 dl g^?1 in dimethyl sulfoxide at 30 °C. They dissolved readily in polar solvents at room temperature. They possess a glass‐transition temperature in the range 210–260 °C and exhibit excellent thermal stability. Copyright © 2004 Society of Chemical Industry     

Hyperbranched polyol/carbon nanofiber composites

Carbon nanofiber (CNF) and carbon nanotube (CNT) composites have enhanced mechanical and electrical properties that make these composites desirable for antistatic and electronic dissipation technology. These applications require a homogenous dispersion of CNFs within a polymer matrix. To improve the compatibility/dispersability of CNFs within a polymer matrix, a hyperbranched polyol CNF composite was synthesized by the chemical modification of oxidized CNFs with glycidol and boron trifluoride diethyl etherate. The resulting polyol CNFs were characterized by TGA, FTIR, TEM/SEM and XPS. The hydroxyl groups were reacted with heptafluorobutyryl chloride to determine the amount of oxidized groups in the sample. The resulting composite was characterized by FTIR and elemental analysis. The amount of hydroxyl groups increased by 550% for the polyol CNFs as compared to the oxidized CNFs and an improvement in dispersion ability was observed.     

Synthesis,characterization of new carboxylic acid‐containing benzoxazine and its cocuring behaviors with bisoxazoline

A new benzoxazine‐benzoic acid (BBA) was synthesized and the structure was conformed by ¹H‐NMR, ¹³C‐NMR, FTIR, etc. The cure behavior of BBA and cocure behavior of BBA with phenylene bisoxazoline (1,3‐PBO) were investigated by differential scanning calorimetry (DSC). It was found that BBA showed a single curing exothermic peak at about 217°C. However, all BBA/1,3‐PBO systems exhibited two exothermic peak. One may be attributed to the reaction between carboxyl groups of BBA and 1,3‐PBO. And the other was attributed to the ring‐opening polymerization of oxazine rings and the reaction between phenolic hydroxyl groups generated by the ring opening of benzoxazine ring and 1,3‐PBO. The curing temperature of benzoxazine containing carboxyl groups could be lowered by the copolymerization of 1,3‐PBO. Thermogravimetric analysis showed that the incorporation of ester–amide groups had a significant effect on decreasing thermal stability and char yield of the cured resin. SEM results indicated that 1,3‐PBO could toughen BBA benzoxazine resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

枯草芽孢杆菌与水体中U(Ⅵ)的作用机制

通过静态吸附-解吸实验,研究了枯草芽孢杆菌对U(Ⅵ)的吸附热力学和动力学,U(Ⅵ)的解吸和菌体内P的释放过程,利用扫描电镜、能谱(SEM-EDS)和红外光谱(FTIR)分析了作用机理。结果表明:当pH=5时,在1 L 50 mg·L^-1的铀溶液中,投加枯草芽孢杆菌1.384 mg(干重,DW),2 h后,铀的去除率和吸附量分别为85.34%和308.31 mg·g^-1(DW)。随着作用时间从2 h延长至48 h,铀的解吸率从52.13%下降至36.25%,菌体内释放到溶液中的P浓度从 0.12 mg·L^-1增加到0.40 mg·L^-1。枯草芽孢杆菌对水体中U(Ⅵ)的吸附行为可以用Langmuir吸附等温模型和准二级动力学方程较好地描述。作用过程是放热,可自发进行。SEM-EDS表明枯草芽孢杆菌与水体中U(Ⅵ)作用后,菌体内部断裂呈短节状,铀沉积在细胞表面及周围,无明显晶体产物生成,FTIR图谱出现UO₂²⁺特征吸收峰,氨基、磷酸基团参与枯草芽孢杆菌与水体中U(Ⅵ)的作用。     

Synthesis and Characterization of Estolide Esters Containing Epoxy and Cyclic Carbonate Groups

The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by ¹H and ¹³C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm^?1 and δ 82 ppm in the FTIR and ¹³C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.     

Studies on the structure of activated carbon fibers activated by phosphoric acid

By solid‐state ¹³C‐ and ³¹P‐NMR, XPS, and FTIR, the chemical structure of activated carbon fiber–P (ACF‐P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen‐containing groups were greatly reduced at high activation temperatures. Different from the ACF‐W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF‐P. The original ACF‐P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF‐P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF‐P activated at lower temperature possessed a large amount of oxygen‐containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of ³¹P‐NMR, P_2p‐XPS, and FTIR at 1620 cm^?1 shifted with the increase of activated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2253–2261, 2003     

Self-emulsifiable soybean oil phosphate ester polyols for low-VOC corrosion resistant coatings

A series of soybean oil phosphate ester polyols (SOPEP) was prepared by reaction of fully epoxidized soybean oil with phosphoric acid and simultanoeous hydrolysis in the presence of a polar solvent. The polyols were characterized by determination of acid value, oxirane number, hydroxyl value, molecular weight (GPC), and FTIR spectra. These polyols with varying amounts of acid phosphate groups could be self-emulsified to form aqueous dispersions after neutralization with organic base. These aqueous dispersion showed varying degrees of stability and their appearance ranged from opaque dispersions to translucent to clear solutions. Waterborne coating compositions were prepared using these aqueous dispersions as principal components and their thermally cured film properties were studied. it was found that by careful selection and formulation, SOPEPs can be successfully used for low-VOC waterborne coating formulations. SOPEPs with 3.5% phosphate ester content showed visibly superior corrosion resistance properties.