The objective of this research was to synthesize biocompatible polyurethanes, with suitable mechanical properties to be used as biomaterials. Polyurethanes were synthesized with polyols derived from castor oil and isophorone diisocyanate (IPDI), hexamethylene diisocyanate and 4,4’-methylenebis (cyclohexyl isocyanate), with the addition of polycaprolactone/chitosan (PCL/Ch). The materials were evaluated for their mechanical properties by determining the stress-strain curves, thermogravimetric analysis, differential scanning calorimetry analysis and contact angle. The biological response of the materials was evaluated by measuring in vitro cell viability on the L-929 mouse fibroblast cell line. The mechanical properties of polyurethanes vary according to the type of polyol and diisocyanate used. The best results were obtained with transesterification-modified polyols with cycloaliphatic diisocyanates. The best results were found for polyurethane synthesized with IPDI and the modified polyol (P.3): 17 MPa of maximum stress at break, 0.937 MPa of Young’s modulus, elongation greater than 250%. Polyurethanes do not have toxic effects and cell viability values exceed 70% on the L-929 fibroblast line. The addition of PCL/Ch improves the cell viability of polyurethanes. The results indicate that the polyurethanes synthesized with polyols derived from castor oil can be used in the design of biomaterials due to the mechanical and biological properties obtained.

Polyurethanes (PUs) are generating increasing interest in the biomedical field due to its characteristic properties. The objective of this article was review general properties of PUs and related with their biomedical applications, also to show the importance of the synthesis of PUs and how each one of the reagents used influences both mechanical properties and biological response of the designed medical devices. It is important to look for a correlation between mechanical properties and biological properties from the synthesis process of the PUs which allow to maintain the biocompatibility required by each medical device. In this work, the PUs are evaluated into three groups of applications: equipment and surgical instruments, temporary applications within the body, and permanent applications within the body. This review can show the broad field of use of PUs in biomedical applications.

Biological activities from polyurethanes (PUs) synthesized from polyols (derived from castor oil) and isophorone diisocyanate were evaluated. In vitro degradability was evaluated by phosphate buffered saline (PBS) and antibacterial degradation with Escherichia coli and Pseudomonas aeruginosa. The biocompatibility was analyzed by: i) the antimicrobial activity against E. coli, S. aureus and P. aeruginosa, and ii) in vitro cytotoxicity assays using mouse embryonic fibroblast cell line L-929 in direct contact with the PUs and with NIH/3T3 cells in indirect contact with the PUs degradation products. PUs with polyol P1 (2,64% molar relation of pentaerythritol and castor oil) was the material with better biodegradation properties: 1.125±0.110% in 72 h by PBS at 100 ºC. In general, all materials were degraded up to 1.000±0.223% and 2.251±0.010% in 72 h by E. coli and P. aeruginosa, respectively. On the other hand, it was determined a close relationship between functionality of polyol and bacterial inhibition. The antibacterial effect of the PUs decreased by 67% for E. coli, 55% for S. aureus and 56% for P. aeruginosa after 24 h. Chemical modification of castor oil did not generate a cytotoxic effect on the tested cell lines. The evaluated materials are suggested as candidates to obtain biomaterials due to their mechanical properties and biocompatibility presented in untransformed cells.

Se sintetizaron poliuretanos (PUs) a partir de polioles derivados del aceite de higuerilla (CO) y diisocianato de de isoforona (IPDI) con relación NCO/OH = 1 a los cuales se les adicionaron retardantes de llama en diferentes concentraciones. Se obtuvieron los polioles P0 y P1 a partir de una reacción de transesterificación del aceite de higuerilla con pentaeritritol. Durante la síntesis al prepolímero de poliuretano se les adicionó diferentes aditivos como el Hidróxido de aluminio (HA) y el Óxido de Molibdeno (OM) para evaluar su efecto como retardantes de llama del poliuretano. Los procesos de degradación térmica y las reacciones de combustión se investigaron mediante análisis termogravimétrico (TGA) y calorimetría diferencial de barrido (DSC). Se evaluó el cambio en el comportamiento mecánico de los materiales sin y con aditivos mediante ensayos de tensión/deformación y dureza shore A. Los resultados obtenidos muestran que el hidróxido de aluminio (HA) tiene mejores características como retardante de llama sobre el óxido de molibdeno (OM) en una proporción de 2.5 % para los poliuretanos obtenidos a partir de aceite de higuerilla y polioles derivados.

Polyurethanes were synthesized from polyols derived from castor oil (CO) and isophorone diisocyanate (IPDI) with NCO/OH=1; different flame retardants were added in different proportions. Polyols (P0 and P1) were obtained from a transesterification reaction of castor oil with pentaerythritol. It was added to the polyurethanes additives such as aluminum hydroxide (AH) and molybdenum oxide (OM) in order to evaluate the effect as flame retardant. Thermal degradation and combustion reactions were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC). The change in the mechanical properties such as stress/strain and shore A hardness were evaluated with and without additives. Aluminum hydroxide (AH) has better characteristics as flame retardant then molybdenum oxide for the polyurethanes obtained from castor oil modified.

Se sintetizaron bioadhesivos tipo poliuretano a partir del aceite de higuerilla y almidón modificado por glucosilación con etilenglicol, y metil éster diisocianato de lisina (LDI). Los bioadhesivos se caracterizaron mediante espectroscopia infrarroja por transformada de Fourier (FTIR), análisis termogravimétrico (TGA) y se determinaron las propiedades mecánicas y de adhesión. Finalmente se determinó el módulo de almacenamiento y la tan(δ) mediante ensayos dinamomecánicos (DMTA). La degradación in vitro del material se llevó a cabo en solución de PBS y se determinó la pérdida de masa. También se realizaron mediciones del ángulo de contacto y absorción de agua con el fin de determinar el cambio en el carácter hidrofílico del material. Finalmente se realizaron pruebas de adsorción de proteínas para determinar la biocompatibilidad del material. El objetivo del estudio fue evaluar el cambio en la estructura del material y el efecto en las propiedades mecánicas y de adhesión, degradabilidad y biocompatibilidad del material con el fin de determinar si los bioadhesivos tipo poliuretano sintetizados pueden ser candidatos en aplicaciones biomédicas.

Polyurethanes were synthesized from castor oil, starch modified via glycosylation with ethylene glycol and lysine methyl ester diisocyanate (LDI). A degradation study of the polyurethanes in PBS solution was performed, and the mass loss was determined for each. The results were compared with homologous material obtained in previous studies using isophorone diisocyanate (IPDI). The degraded polyurethanes were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). The objective of the study was to evaluate the biodegradation characteristics and proteins adsorption of the materials under various conditions and to evaluate the changes in their mechanical and thermal properties caused by the modification of the structures of the hard and soft segments of the polyurethanes with respect to the structure of the diisocyanate used in the synthesis. This study provided an evaluation of segmented polyurethanes with possible biomedical applications.

Biodegradable polyurethanes (PUR) were prepared from polyols derived from castor oil by transesterification of pentaerythritol-modified castor oil and lysine polyisocyanates (LDI and LTI). The polyurethanes obtained were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). The mechanical behavior of the polyurethanes was measured by Shore A hardness and tensile testing (stress-strain curves). The biodegradable nature of the material was determined by contact angle, water absorption tests, and in vitro degradation in PBS solution. This study aims to examine the effect of the structure and functionality of diisocyanate on the mechanical properties and in vitro degradation of the material. The results were compared with homologous materials obtained from isophorone diisocyanate (IPDI) used in previous works. The objective was to evaluate candidate materials that can be potentially used in tissue engineering.

This study reports the preparation of polyurethane adhesives using polyols obtained from castor oil modified by a transesterification reaction with pentaerythritol and starch modified by glycosylation. The physical properties of the polyols such as hydroxyl value were determined and the infrared spectroscopic analysis of the polyols reported. The effect of varying the hydroxyl value in the polyols on physical properties of polyurethane coatings on wood and steel panels was determined. The characterization of polyurethane coatings carried out by IR spectroscopic analysis, scratch hardness resistance, impact resistance, lap shear strength, T-peel strength measurements, solvent resistance and chemical resistant determination were reported.

The chemical structure of the cassava starch was modified by acylation. Cassava starch modified was mixed with urethane prepolymer based on castor oil modified by transesterification (MCO) and isophorone diisocyanate (IPDI) in order to prepare starch-blended thermoplastic polyurethanes. Polyurethanes were exposed to in-vitro degradation then monitored for changes in mass and mechanical and thermal properties over a period of 365 days. The effect of starch modified content on the thermal and physical properties of the resulting materials was detailed investigated by dynamic mechanical thermal analysis (DMTA) and measurements of mechanical properties. The aim of this study was to examine the effect of introducing starch modified into the polyurethane on the properties and in-vitro degradation.

La estructura química del almidón de yuca se modificó mediante una reacción de acilación. El almidón de yuca modificado se mezcló con un prepolímero de uretano obtenido a partir de aceite de ricino modificado por transesterificación (MCO) y diisocianato de isoforona (IPDI) con el fin de preparar mezclas de almidón-poliuretano termoplástico. Los poliuretanos fueron expuestos a degradación in-vitro durante un período de 365 días y se evaluó la pérdida de masa y el cambio de las propiedades mecánicas y térmicas. El objetivo de este estudio fue examinar el efecto de la incorporación de almidón modificado por acilación en el poliuretano sobre las propiedades mecánicas, térmicas y la velocidad de degradación.

Castor oil was modified by transesterification with pentaerithritol. In a parallel step, starch was divided into monosaccharide units by glycosylation in order to obtain products with high hydroxyl content. The values of hydroxyl index were measured according to the content of pentaerithritol and starch used in the synthesis. Novel simultaneous interpenetrating polymer networks (SINs) of polyurethane (PU) and poly(methyl methacrylate) (PMMA) in different weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50 were prepared based on polyol-glucosides. The polyurethane network was created by reacting the poliol-glucosides with isophorone diisocyanate maintaining a molar ratio NCO/OH = 1. The PMMA network was synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as the crosslinker. The SINs were characterized in their mechanical properties, such as Shore A hardness, tensile strength and elongation at break. Thermal stability of SINs was measured using thermogravimetric analysis (TGA). Surface morphology measured using scanning electron microscope (SEM) showed two-phase morphology for all the SINs. SINs based on polyurethane from castor oil modified and poly(methyl methacrylate) show limited compatibility at low concentrations of PMMA, but are totally incompatible at higher concentrations of PMMA.

El aceite de ricino se modificó por transesterificación con pentaeritritol. Paralelamente, se utilizó la reacción de glucosilación con glicerol para dividir el almidón en unidades monosacáridos. El glucósido obtenido reaccionó por transesterificación con el aceite modificado por transesterificación con pentaeritritol. Se determinó el índice de hidroxilo de los poliol-glucósidos en función del contenido de pentaeritritol y almidón utilizados en la síntesis. Se sintetizaron redes interpenetradas de polímero de manera simultánea (SINs) con diferentes relaciones en peso poliuretano/PMMA de 100/0, 90/10, 80/20, 70/30, 60/40 y 50/50. Para la síntesis de la red de poliuretano (PU) se utilizaron los poliol-glucósidos y diisocianato de isoforona (IPDI) o con una relación NCO/OH = 1 y para la síntesis de la red de polimetilmetacrilato (PMMA) se utilizó peróxido de benzoílo como agente iniciador y dimetacrilato de etilenglicol como agente entrecruzante. Los SINs se caracterizaron por sus propiedades fisicomecánicas como resistencia al ataque químico, dureza, resistencia a la tensión y elongación de ruptura. La estabilidad térmica de los SINs se determinó usando análisis termogravimétrico (TGA). La morfología de superficie se determinó usando microscopia electrónica de barrido (SEM) y mostró una morfología de dos fases para todos los SINs.

Chemical modification of cassava starch was conducted through an acylation reaction by using pyridine and propionic anhydride to replace the functional groups of starch. Polyurethane elastomers were prepared using suspensions of the mixture obtained from castor oil and yucca starch that was modified by a propionic anhydride reaction. The suspensions were characterized by means of tests based on The Fourier Transform Infrared Spectroscopy and the Hydroxyl Index. The castor oil-AMP suspensions were used for the PU synthesis. The PUs were characterized by their physical-mechanical properties like tension- deformation and Shore A. hardness, thermal gravimetric analysis and swelling test. The density cross-linking of from swelling tests was determined by applying the Flory-Rehner equation.

Two series of polyols were obtained from castor oil modified by transesterification with various amounts of pentaerythritol and glycerol. The resultant polyol properties were characterized as a function of the hydroxyl functionality. Polyurethane elastomers (PU) were synthesized from the two series of polyols obtained. The crosslink density of those polyurethanes was determined by swelling tests data adjusted to the Flory-Rehner's equation and according to the elasticity theory. The variation of the crosslink density of polyurethanes was studied by following the hydroxyl value of the modified polyol utilized in the synthesis and based on the average structure of each polyurethane repeating unit, as determined by the method of matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI TOF MS). The results show that the PU obtained through castor oil modified with pentaerythritol had a higher crosslink density than PU obtained from unmodified castor oil and from PU prepared by transesterification reaction of castor oil with glycerol. PU based on polyols with the higher hydroxyl functionality presented the higher crosslink density.

Se obtuvo una gama de polioles a partir del aceite de ricino modificado por transesterificación con pentaeritriol y glicerina. Los productos resultantes fueron caracterizados físico-químicamente. Se sintetizaron elastómeros de poliuretano a partir de los polioles derivados del aceite de ricino modificado. La densidad de entrecruzamiento se determinó por ensayos de hinchamiento a partir de la ecuación de Flory-Rehner apoyada en la espectroscopia MALDI TOF MS para determinar la estructura química de la unidad repetitiva promedio del poliuretano. Se estudió la variación de la densidad de entrecruzamiento de los poliuretanos con base en el índice de hidroxilo del poliol utilizado en la síntesis. Los resultados muestran que los PU obtenidos a través de la modificación del aceite con pentaeritriol tienen una mayor densidad de entrecruzamiento que los PU obtenidos a partir del aceite original y de los polioles derivados de la reacción de transesterificación del aceite con glicerina, debido a que estos polioles poseen una mayor funcionalidad hidroxílica.

Castor oil was reacted by transesterification with various percentages in mass of pentaerythritol to obtain different esters of pentaerythritol. Alternatively, glycerol was also used instead of pentaerythritol for the same reaction in order to establish comparative reference products. The products of the reactions were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy in order to detect and quantify (in terms of the molecular mass and structural information) the components of the products obtained. Analysis for hydroxyl value, acid value, viscosity and specific gravity were used to complete the characterization of the polyols obtained and also of the original castor oil. The polymer characterization was accomplished by tensile stress-strain tests, Shore A hardness, thermogravimetric analysis and chemical resistance to solvents.