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1.
Metabolites ; 13(10)2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37887375

RESUMO

Doliocarpus dentatus is thought to have a wide variety of therapeutic phytochemicals that allegedly improve libido and cure impotence. Although a few biomarkers have been identified with potential antinociceptive and cytotoxic properties, an untargeted mass spectrometry-based metabolomics approach has never been undertaken to identify therapeutic biofingerprints for conditions, such as erectile dysfunction, in men. This study executes a preliminary phytochemical screening of the woody vine of two ecotypes of D. dentatus with renowned differences in therapeutic potential for erectile dysfunction. Liquid chromatography-mass spectrometry-based metabolomics was used to screen for flavonoids, terpenoids, and other chemical classes found to contrast between red and white ecotypes. Among the metabolite chemodiversity found in the ecotype screens, using a combination of GNPS, MS-DIAL, and SIRIUS, approximately 847 compounds were annotated at levels 2 to 4, with the majority of compounds falling under lipid and lipid-like molecules, benzenoids and phenylpropanoids, and polyketides, indicative of the contributions of the flavonoid, shikimic acid, and terpenoid biosynthesis pathways. Despite the extensive annotation, we report on 138 tentative compound identifications of potentially therapeutic compounds, with 55 selected compounds at a level-2 annotation, and 22 statistically significant therapeutic biomarkers, the majority of which were polyphenols. Epicatechin methyl gallate, catechin gallate, and proanthocyanidin A2 had the greatest significant differences and were also relatively abundant among the red and white ecotypes. These putatively identified compounds reportedly act as antioxidants, neutralizing damaging free radicals, and lowering cell oxidative stress, thus aiding in potentially preventing cellular damage and promoting overall well-being, especially for treating erectile dysfunction (ED).

2.
ACS Biomater Sci Eng ; 2(3): 336-343, 2016 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-33429537

RESUMO

Conventional engineered polymers are strong, stable, and can interact desirably within the human body in implants and medical devices. However, bacterial colonization of medical devices and implants constructed from these materials results in numerous hospital acquired infections (HAI) and deaths each year. Polytriazole based plastics containing triazole rings and fatty acid derivatives have been synthesized from biological sources without catalysts or solvents. In this study, three amphiphilic polytriazoles with varying triazole density and hydrophilic/hydrophobic segments demonstrated broad spectrum, contact antimicrobial properties against both Gram positive and negative bacteria. SEM analysis of bacteria killed by these polymers evidence membrane damage, indicating that these polymers act by direct contact with bacterial membranes. Surface hydrophobicity of these polymers increased with increasing triazole group density, which also improved the antimicrobial efficacy. This work demonstrates that amphiphilic polytriazoles have antimicrobial properties and that future utilization of triazole modified polymers may produce self-sterilizing materials which resist bacterial contamination and formation of antibiotic resistant organisms, ideal characteristics for medically relevant biomaterials.

3.
Biomed Res Int ; 2014: 792901, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25032224

RESUMO

Azide-alkyne Huisgen "click" chemistry provides new synthetic routes for making thermoplastic polytriazole polymers-without solvent or catalyst. This method was used to polymerize three diester dialkyne monomers with a lipid derived 18 carbon diazide to produce a series of polymers (labelled C18C18, C18C9, and C18C4 based on monomer chain lengths) free of residual solvent and catalyst. Three diester dialkyne monomers were synthesized with ester chain lengths of 4, 9, and 18 carbons from renewable sources. Significant differences in thermal and mechanical properties were observed between C18C9 and the two other polymers. C18C9 presented a lower melting temperature, higher elongation at break, and reduced Young's modulus compared to C18C4 and C18C18. This was due to the "odd-even" effect induced by the number of carbon atoms in the monomers which resulted in orientation of the ester linkages of C18C9 in the same direction, thereby reducing hydrogen bonding. The thermoplastic polytriazoles presented are novel polymers derived from vegetable oil with favourable mechanical and thermal properties suitable for a large range of applications where no residual solvent or catalyst can be tolerated. Their added potential biocompatibility and biodegradability make them ideal for applications in the medical and pharmaceutical industries.


Assuntos
Química Click/métodos , Óleos de Plantas/química , Plásticos/química , Plásticos/síntese química , Triazóis/química , Solventes/química
4.
J Phys Chem B ; 117(47): 14754-62, 2013 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-24171430

RESUMO

Ester group interactions with each other and with the atoms between them were investigated in order to determine dependence of chemical and thermal stabilities of aliphatic diesters on structure. Novel glycol-derived diesters with chemical formula (C17H33COO)2C(n)H(2n) were used as model systems. Chemical stability was determined using (1)H NMR and FTIR, and thermal stability and weight-loss kinetics were examined using nonisothermal TGA. Chemical stability increased with the number of methylene units (n, carbon) between the ester groups until n = 6, and no significant improvement was observed past n > 6. It is argued that other ester-dense materials, including polyesters, would behave similarly. Evidence of a strong dependence of thermal stability on chemical stability is also provided. This work shows that the chemical and thermal stabilities of ester-dense functional materials such as diesters, oligo-esters, and polyesters can be manipulated by varying the distance between the ester groups, and hence the interactions of the electron-withdrawing ester groups with its neighbors.


Assuntos
Glicóis/química , Ésteres/química , Cinética , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
5.
Food Funct ; 4(1): 130-43, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23070069

RESUMO

Pure saturated triacylglycerols (TAGs) in canola oil were used as model systems to analyse oil loss in structured oil both from thermodynamic and kinetic perspectives. Two important parameters which effectively and predictively measure the relative propensity of a solid network to lose/hold oil were defined: (1) the rate of oil loss, K, which is a quantified representation of the kinetics of oil loss and (2) the initial amount of oil susceptible to be lost, i.e., the propensity for oil loss (POL), which is a representation of the thermodynamics of oil binding. It was found that the POL and K values do not always trend in the same fashion, suggesting that the mechanism of oil binding is complex, depending on the structurant's crystalline form locked within the oil network. The two parameters were, however, correlated to the melting and thermal behavior of the structurants, to the polymorphic structures that are obtained during the cooling process and to the habit (shape, size and morphology) of the crystalline phase in the oil. Both POL and K had a strong correlation to the oil loss.


Assuntos
Óleos/química , Triglicerídeos/química , Varredura Diferencial de Calorimetria , Ácidos Graxos Monoinsaturados/química , Cinética , Microscopia de Polarização , Estrutura Molecular , Óleo de Brassica napus , Temperatura , Termodinâmica , Difração de Raios X
6.
Chem Phys Lipids ; 165(1): 77-88, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22119325

RESUMO

The kinetic phase behavior and phase transformation paths of purified tristearoylglycerol (SSS), 3-palmitoyl-1,2-distearoyl-sn-glycerol (PSS) and 1,2-dipalmitoyl-3-stearoyl-sn-glycerol (PPS) were investigated in terms of polymorphism, crystallization and melting. The details of the phase transformation paths were obtained using the heating cycles of two sets of experiments: (a) cooling rate was varied and heating rate fixed and (b) cooling rate was fixed and heating rate varied. Kinetic effects were manifest in all measured properties, underscoring the complexity of the phase transformation paths for each TAG, and the intricate thermodynamics-molecular relationships. For the first time, XRD data obtained for SSS, PSS and PPS TAGs, cooled at rates higher than 0.5°C/min, suggested the formation of a transient structure similar to the so-called α(2)-phase which has been observed in mixed saturated-unsaturated TAGs quenched from the melt. The more stable phases (ß' in PSS and PPS, and ß in SSS) were only observed for cooling rates lower than 1.0°C/min. The kinetic and thermodynamic differences observed in the crystallization, structure and melting of SSS, PSS and PPS are proposed to be mainly due to the disturbances introduced at the "terrace" level via methyl-end group interactions, i.e., the missing of two or four CH(2) groups compared to SSS. The symmetrical SSS with a relatively flat "terrace" crystallizes preferably in the most stable ß-form. Two missing CH(2) groups at the sn-1 position (PSS) introduces enough structural disturbances to promote the relative prevalence and persistence of the ß'-phase, and four missing CH(2) groups at the sn-1 and sn-2 positions (PPS) is relatively too large of a disturbance and therefore favors the α-form.


Assuntos
Glicerol/análogos & derivados , Lipídeos/química , Estearatos/química , Triglicerídeos/química , Varredura Diferencial de Calorimetria , Cristalização , Glicerol/química , Cinética , Conformação Molecular , Transição de Fase , Termodinâmica , Difração de Raios X
7.
Chem Phys Lipids ; 165(1): 105-19, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22119326

RESUMO

The phase behavior of 1-palmitoyl-2,3-distearoyl-sn-glycerol (PSS)/tristearoylglycerol (SSS) binary system was investigated in terms of polymorphism, crystallization and melting behavior, microstructure and solid fat content (SFC) using widely different constant cooling rates. Kinetic phase diagrams were experimentally determined from the DSC heating thermograms and analyzed using a thermodynamic model to account for non-ideality of mixing. The kinetic phase diagram presented a typical eutectic behavior with a eutectic point at the 0.5(PSS) mixture with a probable precipitation line from 0.5(PSS) to 1.0(PSS), regardless of the rate at which the sample was cooled. The eutectic temperature decreased only slightly with increasing cooling rate. PSS has a strong effect on the physical properties of the PSS-SSS mixtures. In fact, the overall phase behavior of the PSS-SSS binary system was determined, for a very large part, by the asymmetrical TAG. Moreover, PSS is a key driver of the high stability observed in crystal growth, polymorphism and phase development. Levels as low as 10% PSS, when cooled slowly, and 30% when cooled rapidly, were found to be sufficient to suppress the effect of thermal processing.


Assuntos
Glicerol/análogos & derivados , Lipídeos/química , Estearatos/química , Triglicerídeos/química , Varredura Diferencial de Calorimetria , Cristalização , Glicerol/química , Cinética , Conformação Molecular , Transição de Fase , Termodinâmica , Difração de Raios X
8.
Chem Phys Lipids ; 165(1): 38-50, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22115831

RESUMO

Four pure jojoba wax-like esters (JLEs), having carbon chain length of 36, 40 (two isomers) and 44, were prepared by Steglish esterification of fatty acids (or acid chlorides) with fatty alcohols at room temperature. Calorimetric and diffraction data was used to elucidate the phase behavior of the esters. The primary thermal parameters (crystallization and melting temperatures) obtained from the DSC of the symmetrical molecules correspond well with the carbon numbers of the JLEs. However, the data also suggests that carbon number is not the only factor since the symmetry of the molecule also plays a significant role in the phase behavior. Overall, the JLEs show very little polymorphic activity at the experimental conditions used, suggesting that they are likely to transform the same way during melting as well as crystallization, a characteristic which may be useful in designing new waxes and lubricants. The XRD data clearly show that the solid phase in all samples consists of a mixture of a ß-phase and a ß'-phase; fully distinguishable by their characteristic diffraction peaks. Subtle differences between the subcell patterns and phase development of the samples were observed. Different layering of the samples was also observed, understandably because of the chain length differences between the compounds. The long spacings were perfectly linearly proportional to the number of carbon atoms. The length of the ester layers with n carbon atoms can be calculated by a formula similar to that used for the layers in linear alkane molecules.


Assuntos
Lubrificantes/síntese química , Ceras/síntese química , Varredura Diferencial de Calorimetria , Cristalização , Ésteres , Ácidos Graxos/química , Lubrificantes/química , Transição de Fase , Termodinâmica , Temperatura de Transição , Ceras/química , Difração de Raios X
9.
J Nanosci Nanotechnol ; 11(8): 7027-32, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22103117

RESUMO

A new class of polylactone was successfully synthesized and utilized for the encapsulation and stabilization of gold nanoparticles. Core/shell nanoparticle architecture, in which a layer of this polymer surrounds the nanoparticle core have been investigated both as a means to improve the stability and surface chemistry and as a way of accessing unique physical properties that are not possible from one nano-material alone. Given the fact that only few systems has so far been developed for the encapsulation of nanoparticles, our success in using a new biodegradable biopolymer with inbuilt functionality reveals the robustness of this work. The biodegradability of this polylactone was evaluated using scanning electron microscopy (SEM). The morphology and stability of these gold-polymer hybrids were evaluated by using the transmission electron microscopy (TEM) and UV-VIS spectroscopy.


Assuntos
Materiais Biocompatíveis , Técnicas Biossensoriais , Ouro , Lipídeos/química , Nanopartículas Metálicas , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura
10.
Chem Phys Lipids ; 163(7): 728-40, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20654601

RESUMO

A robust, well-defined and reproducible method to accurately measure the oil binding capacity (OBC) of structuring fats was developed. The method was validated using two oil/fat model systems, i.e., fully hydrogenated canola oil (FHCO) in canola oil (CO) (FHCO/CO) and fully hydrogenated soybean oil (FHSO) in CO (FHSO/CO). The mixtures were crystallized from the melt down to three different temperatures (15, 25 and 35 degrees C) at constant rates of cooling and the OBC was measured after different periods of storage time. The critical concentration of hard fat at which the solid fat network is stable and effectively binds oil has been also measured for mixtures crystallized at temperatures close to room temperature, i.e., 25 degrees C. Crystal structure, melting behavior, microstructure, and solid fat content of these binary systems have been investigated in relation to the OBC of the solid fat network using X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and wide-line pulsed nuclear magnetic resonance (pNMR) techniques. The two model systems exhibited similar trends in OBC over time, a behavior attributed to their similar TAG composition and polymorphism. However, relatively smaller OBC values were achieved by the CO/FHSO compared to CO/FHCO samples, largely due to differences in their solid network structure. Four successive decreasing linear segments, identifying successive mechanisms of oil migration/binding, were observed in the experimental OBC versus fat weight fraction curves. The critical concentration of hard fat, at which the solid fat network is effective in binding oil, was also determined and found to be approximately 6wt% for both systems.


Assuntos
Gorduras/química , Óleos/química , Varredura Diferencial de Calorimetria , Cristalização , Ácidos Graxos Monoinsaturados/química , Óleo de Brassica napus , Reprodutibilidade dos Testes , Óleo de Soja/química , Difração de Raios X
11.
Chem Phys Lipids ; 163(6): 607-29, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20470766

RESUMO

The binary phase behavior of purified 1,3-dilauroyl-2-stearoyl-sn-glycerol (LSL) and 1,2-dilauroyl-3-stearoyl-sn-glycerol (LLS) was investigated at a slow (0.1 degrees C/min) and a relatively fast (3.0 degrees C/min) cooling rate in terms of melting and crystallization, polymorphism, solid fat content (SFC), hardness and microstructure. Much of the behavior of the system is explained by its polymorphism and the influence of thermal processing. The alpha-form and the beta'-form of a double chain length structure were detected in the mixtures cooled at 3.0 degrees C/min, whereas only the beta'-form was detected in those cooled at 0.1 degrees C/min. X-ray diffraction data as well as thermodynamic data propose that the most stable phases are promoted by the symmetrical LSL. The measured trends in structural characteristics, thermal properties, SFC, relative hardness and microstructure delimit three groups of mixtures which imply a competition between the stabilizing effect of LSL and disordering introduced by kinetic effects: (a) LLS-rich mixtures with LSL molar fractions (X(LSL)) less than 0.3, (b) mixtures with X(LSL) clustered around 0.5 and (c) LSL-rich mixtures with X(LSL)>or=0.7. The balance between ordering and kinetic effects determines the polymorphism of the mixtures, which in turn determines the behavior of the LSL/LLS system. The kinetic phase diagram of the LSL/LLS binary system constructed using heating differential scanning calorimetry thermograms displayed a singularity at the 0.5(LSL) molar fraction which delimits two distinct behaviors: eutectic behavior in one region and monotectic behavior in the other. The molecular interactions, as depicted by a non-ideality parameter of mixing obtained from a thermodynamic model based on the Hildebrand equation, suggests an almost ideal mixing behavior and a moderate tendency to the formation of unlike-pairs in the liquid state.


Assuntos
Glicerol/análogos & derivados , Triglicerídeos/química , Varredura Diferencial de Calorimetria , Cristalização , Cinética , Transição de Fase , Difração de Raios X
12.
Biomacromolecules ; 11(4): 911-8, 2010 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-20232886

RESUMO

An unsaturated terminal diol, 1,18-octadec-9-endiol (ODEDO), and a saturated terminal diol, 1,9-nonanediol (NDO), were synthesized from oleic acid. The feasibility of utilizing these new diols for the production of thermoplastic polyurethanes (TPUs) was demonstrated by reacting them with a fatty acid-derived diisocyanate, 1,7-heptamethylene diisocyanate (HPMDI), and a commercially available petroleum-derived diisocyanate, 1,6-hexamethylene diisocyanate (HDI). One type of phase structure was obtained for both TPUs in this study, owing to the similarity between the ODEDO and NDO molecular structure. In addition, double yielding behavior (observed for the first time in polyurethanes) was observed in the stress-strain curves for both TPU systems. Compared to the TPUs prepared from HDI, the totally biobased TPUs (ODEDO-NDO-HPDMI) demonstrated comparable properties within acceptable tolerances, considering the impacts on physical properties due to the odd-even effect introduced by the HPDMI. This work is the first that establishes the production of linear thermoplastic polyurethanes entirely from lipid feedstock.


Assuntos
Materiais Biocompatíveis/química , Cianatos/química , Glicóis/química , Ácidos Oleicos/química , Poliuretanos/química , Materiais Biocompatíveis/síntese química , Isocianatos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Poliuretanos/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Difração de Raios X
13.
Langmuir ; 26(6): 4311-9, 2010 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-19863120

RESUMO

The isoconversional method, a model-free analysis of the kinetics of liquid-solid transformations, was used to determine the effective activation energy of the nonisothermal crystallization of melts of pure and complex systems of triacylglycerols (TAGs). The method was applied to data from differential scanning calorimetry (DSC) measurements of the heat of crystallization of purified 1,3-dilauroyl-2-stearoyl-sn-glycerol (LSL) and commercially available cocoa butter melts. The method conclusively demonstrated the existence of specific growth modes and critical rates of cooling at specific degrees of conversion. The existence of critical rates suggests that the crystallization mechanism is composed of growth modes that can be effectively treated as mutually exclusive, each being predominant for one range of cooling rates and extent of conversion. Importantly, the data suggests that knowledge of the critical cooling rates at specific rates of conversion can be exploited to select preferred growth modes for lipid networks, with concomitant benefits of structural organization and resultant physical functionality. Differences in transport phenomena induced by different cooling rates suggest the existence of thresholds for particular growth mechanisms and help to explain the overall complexity of lipid crystallization. The results of this model-free analysis may be attributed to the relative importance of nucleation and growth at different stages of crystallization. A mechanistic explanation based on the competing effects of the thermodynamic driving force and limiting heat and transport phenomena is provided to explain the observed behavior. This work, furthermore, offers satisfactory explanations for the noted effect of cooling-rate-induced changes in the physical functionality of lipid networks.


Assuntos
Triglicerídeos/química , Varredura Diferencial de Calorimetria , Cristalização
14.
J Nanosci Nanotechnol ; 9(11): 6326-34, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19908530

RESUMO

A simple preparation method for a nutrient delivery system is presented using nanostructures of oleic acid embedded in canola oil by a two step synthesis procedure. Oleic acid nanostructures in the form of micelles and vesicles were initially prepared and their ability to encapsulate vitamin-C, used as a model nutrient, was evaluated. Dynamic Light Scattering (DLS) analysis and Transmission Electron Microscopy (TEM) confirmed the formation of micelles and vesicles with diameters of 150 nm and 540 nm respectively. Supramolecular structural transformations were observed at specific temperatures, and coincided with the release of a considerable amount of encapsulants followed by a controlled and time bounded release. UV-Vis spectroscopy and various other thermochemical analytical techniques were employed to illustrate the structural transformations and specific environmental stimuli-responsive release of encapsulated materials. The nutrition-enriched nanostructures were successfully transferred to canola oil and the physico-chemical properties evaluated.


Assuntos
Cristalização/métodos , Preparações de Ação Retardada/síntese química , Suplementos Nutricionais/análise , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Ácido Oleico/química , Cápsulas , Composição de Medicamentos/métodos , Alimentos , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
15.
Biomacromolecules ; 10(4): 884-91, 2009 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-19281152

RESUMO

A new linear saturated terminal diisocyanate was synthesized from oleic acid via Curtius rearrangement, and its chemical structure was identified by FTIR, (1)H and (13)C NMR, and MS. The feasibility of utilizing this new diisocyanate for the production of polyurethanes (PUs) was demonstrated by reacting it with commercial petroleum-derived polyols and canola oil-derived polyols, respectively. The physical properties of the PUs prepared from fatty acid-derived diisocyanate were compared to those prepared from the same polyols with a similar but petroleum-derived commercially available diisocyanate: 1,6-hexamethylene diisocyanate. It was found that the fatty acid-derived diisocyanate was capable of producing PUs with comparable properties within acceptable tolerances. This work is the first that establishes the production of linear saturated terminal diisocyanate derived from fatty acids and corresponding PUs mostly from lipid feedstock.


Assuntos
Isocianatos/química , Isocianatos/síntese química , Ácidos Oleicos/química , Óleos de Plantas/química , Poliuretanos/química , Poliuretanos/síntese química , Cromatografia Gasosa , Cianatos/química , Cianatos/metabolismo , Isocianatos/farmacologia , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Teste de Materiais , Polímeros/química , Poliuretanos/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Difração de Raios X
16.
Chem Phys Lipids ; 157(1): 21-39, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18809394

RESUMO

The phase behavior of a binary system constituted of purified 1,3-dicaproyl-2-stearoyl-sn-glycerol (CSC) and 1,2-dicaproyl-3-stearoyl-sn-glycerol (CCS) was investigated at a very slow (0.1 degrees C/min) and a relatively fast (3.0 degrees C/min) cooling rate using differential scanning calorimetry (DSC), low resolution NMR, X-ray diffraction (XRD), and polarized light microscopy (PLM). Related forms of the beta' polymorph were detected for all mixtures as well as a beta form for CSC-rich mixtures. A double chain length (DCL) stacking of the non-mixed CCS-CCS and CSC-CSC phases and a triple chain length (TCL) stacking of mixed CCS-CSC structure were detected for the different beta' forms. The kinetic phase diagram demonstrated an apparent eutectic at the 0.5(CSC) composition when cooled at 0.1 degrees C/min and at the 0.25(CSC) composition when cooled at 3.0 degrees C/min. The application of a thermodynamic model based on the Hildebrand equation suggests that compounds CSC and CCS are not fully miscible. In addition, the miscibility changes according to the structure of the growing solid phase which is dependent on CSC molar ratio as well as on the kinetics. It was also shown that the miscibility is concentration dependent and that the solid phase, which is growing at conditions well away from equilibrium, is determined kinetically. The molecular interactions were found to be strong and to favor the formation of CSC-CCS pairs in the liquid state. CSC and CCS were also shown to be immiscible in the solid state. Depressions in solid fat content (SFC) were observed for both rates. Relatively complex networks made of needle-like, spherulitic and granular crystals were observed in the CSC/CCS system. A pure CSC phase was found to be instrumental in promoting a higher SFC, and more stable polymorphic forms. The microstructure was shown to be strongly dependent on the cooling rate and was linked to the different polymorphic forms observed by DSC and XRD. Correlations between SFC and the eutectic behavior have been observed for the 3.0 degrees C/min cooling rate, but not directly in the case of the 0.1 degrees C/min cooling rate, where slower kinetics which favors the metastable to stable phase conversion processes prevented the same shifts in behavior.


Assuntos
Transição de Fase , Triglicerídeos/química , Varredura Diferencial de Calorimetria , Misturas Complexas/química , Ácidos Graxos/química , Dureza , Microscopia de Polarização , Termodinâmica , Difração de Raios X
17.
Chem Phys Lipids ; 155(1): 43-7, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18640106

RESUMO

A novel highly functionalized aromatic hexa-ol was synthesized by palladium-catalyzed cyclotrimerization of an alkyne fatty acid ester followed by LAH reduction. This polyol product is a novel monomer made from a renewable lipid raw material for the production of polyurethanes, polyesters and polyamides.


Assuntos
Nylons/química , Ácido Oleico/química , Poliésteres/química , Polímeros/química , Poliuretanos/química , Alcinos/química , Catálise , Físico-Química/métodos , Ácidos Dicarboxílicos/química , Ésteres/química , Ácidos Graxos Insaturados/química , Lipídeos/química , Modelos Químicos
18.
Biomacromolecules ; 9(8): 2221-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18624453

RESUMO

Sequential interpenetrating polymer networks (IPNs) were prepared using polyurethane produced from a canola oil based polyol with primary terminal functional groups and poly(methyl methacrylate) (PMMA). The properties of the material were studied and compared to the IPNs made from commercial castor oil using dynamic mechanical analysis, differential scanning calorimetry, as well as tensile measurements. The morphology of the IPNs was investigated using scanning electron microscopy and transmission electron microscopy. The chemical diversity of the starting materials allowed the evaluation of the effects of dangling chains and graftings on the properties of the IPNs. The polymerization process of canola oil based IPNs was accelerated because of the utilization of polyol with primary functional groups, which efficiently lessened the effect of dangling chains and yielded a higher degree of phase mixing. The mechanical properties of canola oil based IPNs containing more than 75 wt % PMMA were comparable to the corresponding castor oil based IPNs; both were superior to those of the constituent polymers due to the finely divided rubber and plastic combination structures in these IPNs. However, when PMMA content was less than 65 wt %, canola oil based IPNs exhibited a typical mechanical behavior of rigid plastics, whereas castor oil based IPNs showed a typical mechanical behavior of soft rubber. It is proposed that these new IPN materials with high performance prepared from alternative renewable resources can prove to be valuable substitutes for existing materials in various applications.


Assuntos
Óleos de Plantas/metabolismo , Polímeros/química , Polimetil Metacrilato/química , Poliuretanos/química , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria/métodos , Desenho de Equipamento , Teste de Materiais , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Plásticos , Estresse Mecânico , Resistência à Tração , Termodinâmica
19.
Biomacromolecules ; 9(5): 1424-33, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18410139

RESUMO

Sequential interpenetrating polymer networks (IPNs) were prepared using polyurethane (PUR) synthesized from canola oil-based polyol with terminal primary functional groups and poly(methyl methacrylate) (PMMA). The properties of the material were evaluated by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and modulated differential scanning calorimetry (MDSC), as well as tensile properties measurements. The morphology of the IPNs was investigated using scanning electron microscopy (SEM) and MDSC. A five-phase morphology, that is, sol phase, PUR-rich phase, PUR-rich interphase, PMMA-rich interphase, and PMMA-rich phase, was observed for all the IPNs by applying a new quantitative method based on the measurement of the differential of reversing heat capacity versus temperature from MDSC, although not confirmed by SEM, most likely due to resolution restrictions. NCO/OH molar ratios (cross-linking density) and compositional variations of PUR/PMMA both affected the thermal properties and phase behaviors of the IPNs. Higher degrees of mixing occurred for the IPN with higher NCO/OH molar ratio (2.0/1.0) at PUR concentration of 25 wt %, whereas for the IPN with lower NCO/OH molar ratio (1.6/1.0), higher degrees of mixing occurred at PUR concentration of 35 wt %. The mechanical properties of the IPNs were superior to those of the constituent polymers due to the finely divided rubber and plastic combination structures in these IPNs.


Assuntos
Ácidos Graxos Monoinsaturados/química , Polimetil Metacrilato/química , Poliuretanos/química , Varredura Diferencial de Calorimetria , Teste de Materiais , Transição de Fase , Óleo de Brassica napus , Propriedades de Superfície , Resistência à Tração
20.
Chem Phys Lipids ; 151(2): 110-24, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18060876

RESUMO

The phase behavior of the 1,3 propanediol dicaprylate/1,3 propanediol distearate (CC/SS) and the 1,3 propanediol dicaprylate/1,3 propanediol dipalmitate (CC/PP) binary systems were investigated using different techniques. The two systems presented essentially the same overall features. XRD measurements detected CC-CC, PP-PP and SS-SS bilayers which crystallized in beta forms but no mixed bilayers for all mixtures. The phase diagrams of both systems were comparable and displayed a monotectic behavior. As strongly evidenced by XRD data, both phase diagrams suggested that CC, PP and SS formed largely separate phases but were probably not completely immiscible. Avrami analysis of SFC vs. time indicated heterogeneous nucleation and spherulitic crystal development from sporadic nuclei. However, noticeable differences in the manifestation of the molecular interactions have been detected at all levels of structure and confirmed by the interchange coupling determined by the enthalpy of melt, the final SFC and the hardness data. This was obviously related to the difference in chain size between SS and PP molecules. The effect on texture was highlighted by drastic microstructural differences between the two systems. Furthermore, the differences in nucleation and crystal growth, the more pronounced tendency for phase separation in the CC/SS system compared to the CC/PP system, and the relatively better crystallization of the CC/PP mixtures, particularly visibly for x(CC)< or =0.3 compared to the CC/SS mixtures were associated with the chain length difference.


Assuntos
Ácidos Graxos/química , Propilenoglicóis/química , Varredura Diferencial de Calorimetria , Caprilatos/química , Cristalização , Palmitatos/química , Transição de Fase , Estearatos/química , Termodinâmica , Temperatura de Transição , Difração de Raios X
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