RESUMO
Thermoplastic polyurethanes (TPUs) are remarkably versatile polymers due to the wide range of raw materials available for their synthesis, resulting in physicochemical characteristics that can be tailored according to the specific requirements of their final applications. In this study, a renewable bio-based polyol obtained from soybean oil is used for the synthesis of TPU via reactive extrusion, and the influence of the bio-based polyol on the multi-phase structure and properties of the TPU is studied. As raw materials, 4,4'-diphenylmethane (MDI), 1,4-butanediol, a fossil-based polyester polyol, and a bio-based polyol are used. The fossil-based to soybean-based polyol ratios studied are 100/0, 99/1, 95/5, 90/10, 80/20, and 50/50% by weight, respectively. The TPUs were characterized by size exclusion chromatography (SEC), gel content analysis, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and contact angle measurements. The results reveal that incorporating the renewable polyol enhances the compatibility between the rigid and flexible segments of the TPU. However, due to its high functionality, the addition of soybean-based polyol can promote cross-linking. This phenomenon reduces the density of hydrogen bonds within the material, also reducing polarity and restricting macromolecular mobility, as corroborated by higher glass transition temperature (Tg) values. Remarkably, the addition of small amounts of the bio-based polyol (up to 5 wt.% of the total polyol content) results in high-molecular-weight TPUs with lower polarity, combined with suitable processability and mechanical properties, thus broadening the range of applications and improving their sustainability.
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Hybrid materials have been studied because in these materials the properties of organic components, such as elasticity and biodegradability, could be combined with the properties of inorganic components, such as good biological response, thereby transforming them into a single material with improved properties. In this work, Class I hybrid materials based on polyester-urea-urethanes and titania were obtained using the modified sol-gel method. This was corroborated using the FT-IR and Raman techniques which highlighted the formation of hydrogen bonds and the presence of Ti-OH groups in the hybrid materials. In addition, the mechanical and thermal properties and degradability were measured using techniques, such as Vickers hardness, TGA, DSC, and hydrolytic degradation; these properties could be tailored according to hybridization between both organic and inorganic components. The results show that Vickers hardness increased by 20% in hybrid materials as compared to polymers; also, the surface hydrophilicity increases in the hybrid materials, improving their cell viability. Furthermore, cytotoxicity in vitro test was carried out using osteoblast cells for intended biomedical applications and they showed non-cytotoxic behavior.
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Thermoplastic polyurethanes (TPUs) are versatile polymers presenting a broad range of properties as a result of their countless combination of raw materialsin essence, isocyanates, polyols, and chain extenders. This study highlights the effect of two different chain extenders and their combination on the structure−property relationships of TPUs synthesized by reactive extrusion. The TPUs were obtained from 4,4-diphenylmethane diisocyanate (MDI), polyester diols, and the chain extenders 1,4-butanediol (BDO) and dipropylene glycol (DPG). The BDO/DPG ratios studied were 100/0, 75/25, 50/50, 25/75, and 0/100 wt.%. The TPUs were characterized by size exclusion chromatography (SEC), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), UV−vis spectroscopy, and physical-mechanical properties. The results indicate that DPG promotes compatibility between rigid (HS) and flexible (SS) segments of TPUs. Consequently, increasing DPG content (>75 wt.%) reduced the organization of the rigid segments and the degree of phase separation, increasing the polydispersity of the interdomain distance and the transparency in the UV−visible spectrum of the TPUs. Furthermore, increasing DPG content also reduced the amount of hydrogen bonds present in the rigid phase, reducing or extinguishing its glass transition temperature (TgHS) and melting temperature (Tm), and increasing the glass transition temperature of the flexible phase (TgSS). Therefore, increasing DPG content leads to a deterioration in mechanical properties and hydrolysis resistance.
RESUMO
In the present work, the synthesis of segmented polyurethanes functionalized with catechol moieties within the hard or the soft segment is presented. For this purpose, a synthetic route of a new catechol diol was designed. The direct insertion of this catechol-free derivative into the rigid phase led to segmented polyurethanes with low performance (σmax ≈ 4.5 MPa). Nevertheless, when the derivative was formally located within the soft segment, the mechanical properties of the corresponding functionalized polyurethane improved considerably (σmax ≈ 16.3 MPa), owing to a significant increase in the degree of polymerization. It is proposed that this difference in reactivity could probably be attributed to a hampering effect of this catecholic ring during the polyaddition reaction. To corroborate this hypothesis, a protection of the aromatic ring was carried out, blocking the hampering effect and avoiding secondary reactions. The polyurethane bearing the protected catechol showed the highest molecular weight and the highest stress at break described to date (σmax ≈ 66.1 MPa) for these kind of catechol-functionalized polyurethanes. Therefore, this new approach allows for the obtention of high-performance polyurethane films and can be applied in different sectors, benefiting from the molecular adhesion introduced by the catechol ring.
Assuntos
Anel Fibroso/metabolismo , Materiais Revestidos Biocompatíveis/síntese química , Poliuretanos/síntese química , Adesivos Teciduais/síntese química , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/administração & dosagem , Materiais Revestidos Biocompatíveis/metabolismo , Colágeno/química , Haplorrinos , Injeções , Cinética , Fenômenos Mecânicos , Camundongos , Cimento de Policarboxilato/química , Poliuretanos/administração & dosagem , Poliuretanos/metabolismo , Propriedades de Superfície , Temperatura , Termodinâmica , Aderências Teciduais/metabolismo , Adesivos Teciduais/administração & dosagem , Adesivos Teciduais/metabolismo , ViscosidadeRESUMO
Two series of segmented polyurethanes were obtained and their mechanical and thermal properties as well as their biodegradability and cytotoxicity were evaluated. The chemical nature of the polyurethanes was varied by using either 1,4 butanediol (poly-ester-urethanes, PEUs) or l-lysine ethyl ester dihydrochloride (poly-ester-urea-urethanes, PEUUs) as chain extenders. Results showed that varying the hard segment influenced the thermal and mechanical properties of the obtained polymers. PEUs showed strain and hardness values of about 10â»20 MPa and 10â»65 MPa, respectively. These values were higher than the obtained values for the PEUUs due to the phase segregation and the higher crystallinity observed for the polyester-urethanes (PEUs); phase segregation was also observed and analyzed by XRD and DSC. Moreover, both series of polymers showed hydrolytic degradation when they were submerged in PBS until 90 days with 20% of weight loss. In vitro tests using a Human Osteoblastic cell line (Hob) showed an average of 80% of cell viability and good adhesion for both series of polymers.
RESUMO
Abstract Bioresorbable linear poly(ether-ester-urethane)s with different hydrophilic characteristics were synthesized from triblock copolymers of poly(ε-caprolactone)-poly(ethylene oxide)-poly(ε-caprolactone) (PCL-PEO) as macrodiols, and L-lysine diisocyanate (LDI) or hexamethylenediisocyanate (HDI) were used as the required diisocyanates. Macrodiols were obtained by ring-opening polymerization (ROP) of ε-caprolactone (CL). Polyurethanes were synthesized by the reaction of the triblock copolymers with LDI or HDI in solution using stannous 2-ethylhexanoate as catalyst. Polyurethane tablets were fabricated and investigated as prospective drug delivery systems. The effect of the PEO content on the polymers' performance as drug carriers was evaluated. It was found that water provoked more swelling and erosion of polymers with higher contents of PEO. The hydrocortisone release profiles were analyzed using the Ritger-Peppas approximation. An anomalous release behaviour (values of n higher than 0.5) was found for most of the analyzed samples.
Assuntos
Comprimidos/farmacocinética , Hidrocortisona/farmacocinética , Poliuretanos/síntese química , Liberação Controlada de FármacosRESUMO
This paper describes the preparation and characterization of water-soluble urethane oligomers bearing protected isocyanate groups. It also points out its ability to crosslink decellularized pericardium, as a model collagen scaffold, and to adjust their structural characteristics. A library of oligourethanes was synthesized by varying the molecular weight (Mw 400, 600, 1000 or 2000 g mol-1) of the poly(ethylene glycol) and the type of aliphatic diisocyanate (isophorone diisocyanate/IPDI or hexamethylene diisocyanate/HDI). 1H and 13C NMR, FTIR and mass spectrometry demonstrated that the crosslinkers are composed of chains with carbamoylsulfonate end groups that have trimeric and pentameric oligourethanes, and monomeric diisocyanate. The degree of crosslinking and hence the in vitro degradation susceptibility of the decellularized pericardium were inversely related to the Mw of the oligourethanes. The toxicity of the extractable products from oligourethane-collagen materials toward fibroblasts and macrophages was found to be lower for the crosslinker derived from IPDI than for those derived from HDI. On the other hand, the resistance to collagenase or oxidative degradation of the bovine pericardium crosslinked with HDI/oligourethane was higher than the one prepared with IPDI/oligourethane. As the Mw of the oligomers regulates the degree of crosslinking while the chemical composition influences the cytocompatibility and biodegradation of decellularized pericardium, these urethane oligomers can be used as safer crosslinkers for other protein-based biomaterials.
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Two new neutral hexacoordinated silicon complexes with SiN(4)O(2) (6) and SiN(3)O(2)C (7) coordinating frameworks were synthesized by reaction of the O,N,N,O-donor salen-type ligand 1,2-bis[[(2-hydroxy-4-methoxyphenyl)(phenyl)methylene]amino]ethane (H(2)salen*) with Si(NCS)(4) and HMeSi(NCS)(2), respectively. The complexes 6 [Si(salen*)(NCS)(2)] and 7 [Si(salen*)Me(NCS)] were studied in the solid-state by (29)Si and (15)N CP/MAS NMR and in solution by (1)H, (13)C, and (29)Si insensitive nuclei enhanced by polarization transfer (INEPT) NMR, UV/vis and FT-IR spectroscopy. Elemental analysis and single-crystal X-ray diffraction analysis were used to confirm the composition and structure for compounds 6 and 7. Both complexes contain the dianionic salen-type ligand coordinated in an equatorial fashion to the silicon center, while the axial positions are occupied by two thiocyanato-N ligands for 6 and one thiocyanato-N and one methyl ligand for 7. Complex 6, which contains two Si-NCS functional groups, was used as monomer to produce a mixture of linear oligosilanes with a hexacoordinated silicon backbone (formulated SCN-[Si(salen*)](n)-NCS, n = 2-8) 8, via a Wurtz-type coupling reaction. Oligomers 8 were identified by solid-state (29)Si cross polarization-magic angle spinning NMR and solution (1)H and (29)Si NMR spectroscopy, matrix assisted laser desorption ionization-time of flight (MALDI-TOF), gel-permeation chromatography (GPC), FT-IR, UV/vis spectroscopy and thermogravimetric analysis (TGA). Conclusive evidence of the oligomeric nature of 8 was provided by MALDI-TOF spectrometry and was supported by quantitative solution (29)Si NMR and GPC studies.
RESUMO
Bioresorbable linear poly(ester-ether urethane)s with different hydrophilic character were synthesized from block copolymers of poly(epsilon-caprolactone)-poly(ethylene oxide)-poly(epsilon-caprolactone) (PCL-PEO-PCL) as macrodiols, and L-lysine diisocyanate (LDI). A series of PCL-PEO-PCL triblock copolymers with different PEO and PCL chain length was obtained by reacting PEO with epsilon-caprolactone. Polyurethanes were synthesized by reacting the triblock copolymers with LDI in solution using stannous 2-ethylhexanoate as catalyst. The prepared triblock copolymers and polyurethanes were fully characterized by proton nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, and wide-angle X-ray diffraction. Water uptake, hydrolytic stability, and tensile properties of polyurethanes with different composition were evaluated and discussed in terms of the chain length and molecular weight of the polymers and its block components. Water uptake seems to depend on the ethylene oxide unit content of the polyurethane regardless of the triblock structure. Mechanical properties of the synthesized polymers were strongly affected by the molecular weight achieved during polymerization. The use of triblock macrodiols with different hydrophilicity allowed the preparation of a series of polyurethanes having a broad range of properties.