A structural study of epoxidized natural rubber (ENR‐50) ring opening under mild acidic condition

A structural study of ring opening reaction of purified epoxidized natural rubber (ENR) with acetic acid was conducted using the NMR techniques and its thermal characteristic was evaluated with Thermal gravimetry/Differential Thermal Gravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC) analyses. ¹H‐NMR revealed that 19.56% of epoxide was ring‐opened from the total amount of the epoxide unit in ENR‐50 and this was supported by Fourier Transform Infrared (FTIR) spectroscopy. ¹³C‐NMR suggests the fixation of alkyl (R) i.e., acetate group to the epoxide carbon via ester linkage and formation of hydroxyl groups in the polymer chains. The attachment location of R occurred at both most (↑) and least (↓) hindered carbons of the epoxide. The TG/DTG results of acid treated ENR‐50 showed three decomposition steps at 235–338, 338–523, 523–627 °C due to the presence of the polymer chains mixture, i.e., ring‐opened and intact epoxide of ENR‐50. This increases the T_g value of acid treated ENR‐50 at 24.6 °C as compared to purified ENR‐50 at −17.7 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44123.     

Cyclic alkyl ketene oligomers

Two alkyl ketene oligomers (AKOs) with almost 100% purities were prepared in high yields of 80–90% from palmitic acid chloride and alkyl ketene dimer (prepared from palmitic acid chloride) in the presence of amine promoters. Two AKOs thus obtained had quite similar molecular weights (1000–10,000), carbon/hydrogen contents, X‐ray diffraction patterns, solution‐state ¹³C‐NMR spectra, and water‐contact angles. However, two AKOs had different size‐exclusion chromatograms, differential scanning calorimetric curves, FTIR spectra, and solution‐state ¹³C‐NMR spectra for ¹³C‐labeled AKOs. Based on the ¹³C‐NMR spectra of ¹³C‐unlabeled AKOs, AKOs are likely to have cyclic structures, thus having the limited molecular weights of <10,000. The results of FTIR spectra and ¹³C‐NMR spectra of ¹³C‐labeled AKOs indicated that three different repeating units were linked with various molar ratios and various connection patterns and combinations, constituting the cyclic AKOs. As a result, ¹³C‐NMR spectra of ¹³C‐labeled AKOs showed quite a number of carbon signals due to various ¹³C?O and ¹³C?C structures present in AKOs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3668–3673, 2013     

Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

The aim of this study was to investigate whether hydroperoxides are formed in the autoxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and absence of α‐tocopherol. The existence of hydroperoxide protons was confirmed by D₂O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH₄. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The ¹³C and ¹HNMR spectra of a mixture of 9‐hydroper‐oxy‐10‐trans,12‐cis‐octadecadienoic acid methyl ester (9‐OOH) and 13‐hydroperoxy‐9‐cis, 11‐trans‐octadecadienoic acid methyl ester (13‐OOH), which are formed during the autoxidation of methyl linoleate, were studied in detail to allow the comparison between the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides. The ¹³CNMR spectra of samples enriched with one of the two linoleate hydroperoxide isomers were assigned using 2D NMR techniques, namely Correlated Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gHMBC), and gradient Heteronuclear Single Quantum Correlation (gHSQC). The ¹³C and ¹H NMR experiments performed in this study show that hydroperoxides are formed during the autoxidation of CLA methyl ester both in the presence and absence of α‐tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides.     

13C‐NMR study on cure‐accelerated phenol‐formaldehyde resins with carbonates

Both liquid‐ and solid‐state carbon‐13–nuclear magnetic resonance (¹³C‐NMR) spectroscopies were used to investigate the cure acceleration effects of three carbonates (propylene carbonate, sodium carbonate, and potassium carbonate) on liquid and cured phenol‐formaldehyde (PF) resins. The liquid‐phase ¹³C‐NMR spectra showed that the cure acceleration mechanism in the propylene carbonate‐added PF resin seemed to be involved in increasing reactivity of the phenol rings, whereas the addition of both sodium carbonate and potassium carbonate into PF resin apparently resulted in the presence of ortho–ortho methylene linkages. Proton spin‐lattice rotating frame relaxation time (T_1ρH) measured by solid‐state ¹³C cross polarization/magic‐angle spinning NMR spectroscopy was smaller for the cure‐accelerated PF resins than that of the control PF resin. The result indicated that the cure‐accelerated PF resins are less rigid than the control PF resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1284–1293, 2000     

Complexation of titanium alkoxides with pentenoic acid and allylacetoacetate and their hydrolysis and addition reactions with H‐silanes

Complexation reactions of titanium tetraethoxide [Ti(OEt)₄] and titanium tetra‐n‐butoxide [Ti(OBuⁿ)₄] with 3‐pentenoic acid (PA) and allylacetoacetate (AAA), in a 1 : 1M ratio, were studied in ethanol solution at room temperature. ¹³C‐NMR and FTIR spectra showed that all PA and AAA completely reacted with both titanium alkoxides. Hydridosilane compounds such as triethoxysilane and triethylsilane were added to titanium chelate complexes in a 1 : 1M ratio. The investigation of products by ¹³C‐ and ²⁹Si‐NMR and FTIR showed additions of ? SiH to the C?C double bond. The hydrolysis of titanium–PA and AAA complexes, by water in 1 : 4 ratios, resulted in released PA in an amount of 10% and AAA of 20%. The stability of hydrolyzed products was investigated by ¹³C‐NMR, ²⁹Si‐NMR, and FTIR. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 790–796, 2005     

13C‐NMR study on cure‐accelerated phenol–formaldehyde resins with carbonates

Both liquid‐ and solid‐state ¹³C‐NMR spectroscopies were employed to investigate the cure‐acceleration effects of three carbonates [propylene carbonate (PC), sodium carbonate (NC), and potassium carbonate (KC)] on liquid and cured phenol–formaldehyde (PF) resins. The liquid‐phase ¹³C‐NMR spectra showed that the cure‐acceleration mechanism in the PC‐added PF resin seemed to be involved in increasing reactivity of the phenol rings, while the addition of both NC and KC into PF resin apparently resulted in the presence of ortho–ortho methylene linkages. Proton spin‐lattice rotating frame relaxation time (T_1ρH) measured by solid‐state ¹³C‐CP/MAS‐NMR spectroscopy was smaller for the cure‐accelerated PF resins than for that of the control PF resin. The result indicated that cure‐accelerated PF resins are less rigid than the control PF resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 841–851, 2000     

Synthesis and biodegradability evaluation of 2‐methylene‐1,3‐dioxepane and styrene copolymers

Biodegradable copolymers of 2‐methylene‐1,3‐dioxepane (MDO) and styrene (ST) were synthesized by free‐radical copolymerization using di‐t‐butyl peroxide (DTBP) as the initiator. The copolymers containing ester units were characterized by Fourier transform infrared (FTIR), ¹H‐NMR, and ¹³C‐NMR spectroscopy. Their molecular weight and polydispersity index were determined by gel permeation chromatography (GPC). In vitro enzymatic degradation of poly(MDO‐co‐ST) was performed at 37°C in phosphate buffer solution (PBS, pH = 7.4) in the presence of Pseudomonas lipase or crude enzyme extracted from earthworm. The experiment showed that incorporating ester units into C? C backbone chain of polystyrene would result in a biodegradable copolymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1146–1151, 2007     

Synthesis,characterization and cytotoxicity of novel modified poly[(maleic anhydride)‐ co‐(vinyl acetate)]/noradrenaline conjugate

Poly[(maleic anhydride)‐co‐(vinyl acetate)] (MAVA) copolymer was synthesized by free radical polymerization reaction, in methyl ethyl ketone at 80 °C, using benzoyl peroxide as the initiator. The copolymer was then modified with a biomolecule, noradrenaline (NA). The modification reaction was performed at 70 °C in dimethylformamide containing triethylamine as the catalyst. The modified polymer was named MAVA/NA. Structural characterization of the copolymer and the modified product was carried out by Fourier transform infrared (FTIR) and ¹H NMR and ¹³C NMR spectroscopy. The FTIR, ¹H NMR and ¹³C NMR spectra confirmed that NA was successfully covalently bound to the MAVA copolymer backbone. Surface morphology was visualized by atomic force microscopy. The cumulative release of NA from MAVA/NA was determined in phosphate buffered saline solution for 7 days at 37 °C and compared with MAVA. Cytotoxicity of the MAVA/NA was evaluated by using a mouse fibroblast cell line (L929). Results obtained indicated that MAVA/NA had almost no toxicity and no negative effect on cell viability at 250 µg mL^?1 concentration. © 2012 Society of Chemical Industry     

Copolymer hydrogel microspheres consisting of modified sulfate chondroitin‐co‐poly(N‐isopropylacrylamide)

Modified chondroitin sulfate (π‐CdS) microspheres were synthesized by way of crosslinking‐copolymerization reaction with N‐isopropylacrylamide (NIPAAm), yielding CdS‐co‐PNIPAAm copolymer network. The incorporation of vinyl groups onto the CdS was processed with the use of glycidyl methacrylate (GMA) in an aqueous solution of pH 3.5 under stirring speed of 800 rpm at 50°C. ¹³C NMR and ¹H NMR spectra of CdS treated with the GMA indicated the formation of 3‐methacryloyl‐1‐glyceryl ester of π‐CdS and 3‐methacryloyl‐2‐glyceryl ester of π‐CdS that are the reaction products resultant of an epoxide ring‐opening mechanism via. The synthesis of microspheres was performed via radical reaction of the vinyl groups at the π‐CdS with vinyl groups at the NIPAAm in a water−benzyl alcohol microemulsion. The formation of spherical structures is the result of the polymerization‐crosslinking reaction of the π‐CdS with the NIPAAm monomers at the droplets of water, in view that both reactants have hydrophilic characteristics at the temperature at which the reaction was processed. The pure CdS hydrogel microspheres showed a slightly cracked structure with a lower diameter range while the CdS‐co‐PNIPAAm hydrogel microspheres showed a flat and tight structure with a more regular mass distribution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Development and characterization of a defatted soy flour-based bio-adhesive crosslinked by 1,2,3,4-butanetetracarboxylic acid

A new, environmentally friendly defatted soy flour-based bio-adhesive was developed by using the cross-linker 1,2,3,4-butanetetracarboxylic acid (BTCA). The reaction between BTCA and defatted soy flour was confirmed by assaying the free amino groups, by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, and ¹³C nuclear magnetic resonance (¹³C NMR). Three-ply plywood was fabricated to measure wet shear strength, and the cross-section and thermal behavior of resultant adhesives were characterized in detail. A decrease in the free amino group content, a new ester peak in the FTIR spectra, a weaker resonance at 65.4–76.2 ppm in ¹³C NMR, and a decrease in crystallinity confirmed that BTCA was successfully crosslinked with defatted soy flour. The resulting crosslinked bio-adhesive showed improved wet shear strength (1.36 MPa) and a reduced sol fraction (24.8%). The crosslinked bio-adhesive displayed enhanced thermal stability, and had a more uniform surface based on thermogravimetric analysis and scanning electron microscopy. The results suggest BTCA can be used to prepare high-performance environmentally friendly defatted soy flour-based bio-adhesives.     

Synthesis and characterization of dicyanate monomers containing methylene spacers

The bisphenols containing methylene spacer were prepared by treating eugenol/2‐allyl phenol with 2,6‐dimethyl phenol/guiacol/o‐cresol in the presence of AlCl₃. All the bisphenols were converted to their respective cyanate esters by treating with CNBr. The structural confirmation was done by FTIR, ¹H NMR, ¹³C NMR spectral methods, and elemental analysis. Thermal characterization was done by DSC and TGA. DSC transition shows that the T_g is in the range of 208–239°C. The T_g is highest for the cyanate ester Cy(b) with symmetric structure. The T_g of the cured network depends on the length and symmetry of the monomer, T_g being higher for shorter and the para‐substituted monomers. The T₁₀ values are in the range of 364–381°C. The char yield is in the range of 47–53%. From the char yield, the limiting oxygen index (LOI) value was determined, which is used to confirm the flame retardancy of the cyanate ester resins. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and Characterization of Polyethylene Glycol Diesters from Estolides Containing Epoxides and Diols

Estolides from oleic acid, 12-hydroxystearic acid, and methyl ricinoleate were synthesized and converted to polyethylene glycol (PEG) diesters. Oleic estolide was synthesized from oleic acid as a homo-oligomeric material using perchloric acid in 68.8% yield and an estolide number (EN) value of 1.29. Estolides from 12-hydroxystearic acid were homo-oligomers made by heating under vacuum at 150 °C for 24 hours to give a quantitative yield of estolide with an EN value of 2.55. Oleic acid-based estolides and 12-hydroxystearic acid-based estolide were esterified with PEG-200 diol to form PEG 200 diesters. Ricinoleate estolides was capped with lauric acid or 12-hydroxystearic estolide by reacting methyl ricinoleate with the corresponding fatty acids at 150 °C using tin(II) octoate as a catalyst. The corresponding estolides were transesterified with PEG-200 diol to form the diesters. The residual olefin of ricinoleate was then epoxidized and underwent ring opening hydrolysis to form the corresponding diol. NMR spectroscopy (¹H, ¹³C, distortionless enhancement by polarization transfer, heteronuclear single quantum correlation, heteronuclear multiple bond correlation, and correlated spectroscopy) was used to characterize the products.     

Synthesis,characteristic, and properties of waterborne polyurethane based on natural rubber

A series of new waterborne polyurethanes (WPUs) was successfully prepared by prepolymer process from renewable source, hydroxytelechelic natural rubber (HTNR), with different amounts of DMPA (1.6–8.4 wt %), different molecular weights (1000–4000 g mol^?1), and different levels of epoxide (0%–20%) of HTNR. It was found that the urethane conversions of prepolymer were over 80% as calculated by FTIR technique. The resulting HTNR2000‐based WPUs exhibit a uniform particle size, which decreases from 420‐ to 83‐nm diameters with an increase in the amount of DMPA from 2.9 to 6.6 wt %. The particle size also decreases with an increase of soft segment or with an increase of epoxide content. They are well stable more over 6 months and without a significant difference in particle size compared with starting of them. Chemical structure of WPU films was confirmed by FTIR, ¹H‐NMR, and ¹³C‐NMR. Molecular weight and polydispersity were determined by SEC. In addition, thermal and water uptake properties were investigated. The experimental results reveal that the DMPA content, molecular weight of HTNR, and epoxide content play an important key role in water uptake and thermal properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and properties of elastic polyurethane‐imide

A new synthesis route for elastic polyurethane‐imides (EPUIs) has been established by a method involving the use of urea. Various EPUIs were synthesized from polyurethane‐urea, which was prepared from 4,4′‐diphenylmethane diisocyanate (MDI), polyoxytetramethylene glycol (PTMG) and 4,4′‐diphenylmethanediamine (MDA), and pyromellitic dianhydride in N‐methyl‐2‐pyrrolidone (NMP). Flexible films were cast from these solutions that had different inherent viscosities. Imidization of the EPUI films was completed at 200°C for 4 h in vacuo. The EPUIs were determined by FTIR, ¹H NMR, and ¹³C NMR spectra. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Convenient preparation of fatty ester cyclic carbonates

The cyclic carbonate moiety finds many industrial applications because of its unique chemistry and properties. Phosgene, a highly toxic and corrosive reagent, has been utilized in the past to prepare low yields of fatty ester compounds ( 1 ) that contain a five‐membered cyclic carbonate group. Herein, we show (CH₃)₄N^+?HCO₃, tetramethylammonium hydrogen carbonate (TMAHC), to react efficiently with methyl or 2‐ethylhexyl 9(10)chloro‐10(9)‐hydroxyoctadecanoate at 50–55 °C to give methyl or 2‐ethylhexyl 8‐(2‐oxo‐5‐octyl‐1,3‐dioxolan‐4‐yl)octanoate, 1a and 1b , respectively. These fatty acid ester carbonates were isolated in good yields ranging from 84% to 91% after purification by vacuum distillation. The purified fatty ester carbonate compounds were characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gas chromatography‐mass spectrometry using electron impact ionization and positive chemical ionization techniques. This work demonstrates that the five‐membered cyclic carbonate ring can be effectively introduced onto the alkyl chains of fatty acid esters using fatty ester chlorohydrins and (CH₃)₄N^+?HCO₃ chemistry. The well‐known lubricating and polymeric properties of the carbonate moiety make these interesting cyclic oleochemical carbonates potential candidates for industrial lubricant, plasticizer, or polymer applications.     

Thermally activated polymerization behavior of bisphenol‐S/methylamine‐based benzoxazine

A bifunctional benzoxazine monomer, 6,6′‐bis(3‐methyl‐3,4‐dihydro‐2H‐benzo[e] [1,3]oxazinyl) sulfone (BS‐m), was synthesized from bisphenol‐S, methylamine, and formaldehyde via a solution method. The chemical structure of BS‐m was characterized with ¹H and ¹³C‐nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The ring‐opening polymerization reaction of BS‐m monomer was studied by FTIR, ¹³C solid‐state NMR, and differential scanning calorimetry. With the polymerization reaction proceeding, the intensities of the FTIR absorption peaks of CH₂, C? O? C, and C? N? C of the oxazine ring decreased gradually, and some of these absorption peaks disappeared. The shapes and intensities of the absorption peaks associated with benzene ring, sulfone group, and aromatic C? S bond changed in various ways. The changes in the solid‐state ¹³C‐NMR pattern, including chemical shifts, intensity of resonances, and line‐width, were observed from the spectra of BS‐m and the corresponding polybenzoxazine. The melting process of BS‐m overlapped with the beginning of the ring‐opening polymerization reaction. The polymerization kinetic parameters were evaluated for nonisothermal and isothermal polymerization of BS‐m. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Random copolymerization of 2,2‐dimethyltri methylene carbonate and ε‐caprolactone using a rare‐earth tris(4‐tert‐butylphenolate)s as a single‐component initiator

Highly random copolymers of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (CL) were synthesized by single component rare‐earth tris(4‐tert‐butylphenolate)s [Ln(OTBP)₃] for the first time. The influences of reaction conditions on the copolymerization initiated by La(OTBP)₃ have been examined in detail. The monomer reactivity ratios of DTC and CL determined by the Fineman–Ross method are 4.0 for r_DTC and 0.27 for r_CL. The microstructure of the copolymer was determined by the analyses of the diads DTC–DTC, DTC–CL, CL–DTC and CL–CL of the ¹H NMR spectra. The high degree of randomness of the chain structure was further confirmed by the ¹³C NMR spectra and differential scanning calorimetry. The thermal properties of the copolymers as a function of composition are reported. The mechanism investigated by ¹H NMR data indicates that the rare‐earth tris(4‐tert‐butylphenolate)s initiate the ring‐opening copolymerization of DTC and CL with acyl‐oxygen bond cleavages of the monomers. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of epoxy/amine terminated amide‐imide‐imide blends

A new amine terminated amide‐imide (ATAI) was synthesized by the polycondensation reaction of tetrimide dicarboxylic acid containing bulky m‐chloro phenyl pendant with p‐phenylene diamine. The structure of all the prepared compounds were confirmed by FTIR,¹H‐NMR and ¹³C‐NMR techniques. This new diamine was then used to cure epoxy resin namely diglycidyl ester of bisphenol‐A and the cure reaction was studied by Differential scanning calorimetry. The cured blends show better thermal properties. The T_g of the epoxy resin was increased from 134°C to 156°C on addition of 6% of ATAI. The DMA results indicate that the polymer blend with 8% ATAI composition has higher storage modulus compared to 3% and 6% ATAI composition. The polymer blends with 3% and 6% ATAI composition have higher crosslinking density and lower intersegmental and intrasegmental friction coefficients than 8% ATAI composition. In the DMA curves an increase in the peak half‐width was observed with increasing ATAI composition, indicating the possibility of the existence of more than one phase with increasing ATAI concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of a novel functional monomer containing cyano and propenylphenoxy groups and the properties of its copolymer with bismaleimide (BMI)

A novel functional monomer containing cyano and propenylphenoxy groups, 2,6‐di{2‐[(E)‐l‐propenyl]phenoxy}benzonitrile (DPPB) was prepared with high stereospecificity by the reaction of 2,6‐dichlorobenzonitrile and 2‐allylphenol in a mixed solvent system of N‐methylpyrrolidone (NMP)/toluene in the presence of anhydrous potassium carbonate. The chemical structure of the product was characterized by FTIR, ¹H NMR and ¹³C NMR. The monomer was then used to modify a popular commercial bismaleimide, 4,4‐bismaleimidodiphenylmethane (BMDPM), for improving the shear strength of the resin. The results showed that the modified resin could attain 4.7 times the shear strength of neat BMDPM and good heat resistance when the composition of DPPB in the modified resin was 45% (by weight). © 2002 Society of Chemical Industry     

Structural characterization of oligomers from the polycondensation of citric acid with ethylene glycol and long‐chain aliphatic alcohols

The structural characterization of polyesters of citric acid (CA) with ethylene glycol and long‐chain aliphatic alcohols (ROH), prepared by the composition of the reaction mixture being adjusted slightly away from stoichiometric equivalence, was performed with ¹H‐ and ¹³C‐NMR spectroscopy. The aliphatic alcohols employed were 1‐decanol, 1‐dodecanol, and 1‐octadecanol. The ¹³C‐NMR carbonyl region presented four groups of signals, two corresponding to the ester groups and two corresponding to the acid groups. However, symmetric and asymmetric groups of CA moieties were identified in the ¹³C‐NMR spectra. The ester yield from ROH decreased as the number of carbon atoms in the alcohols increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 302–306, 2003