Abstract Firstly, this work shows the crosslinking of the Polyurethane/Single Wall Carbon Nanotube/ Polymethyl Methacrylate (PU/SWCNT/PMMA) nanocomposite at 298.15K using the PM3 semi-empirical method (Parameterized Model number 3), where the reaction was spontaneous and endothermic. The log P indicated a hydrophobic character. Subsequently, the Monte Carlo simulation was carried out at 303.15, 313.15 and 323.15K, where the Gibbs free energy and the dipole moment increased. However, the reactions were spontaneous and endothermic. The log P had hydrophobic character. Additionally, the entropy decreased due to the increase in intermolecular forces in the nanocomposite. Furthermore, FTIR analysis had similar vibrational frequencies, which was verified with the electronic distribution. Thus, this nanocomposite would have excellent physical and thermal stability, and it does not have reactions to polar solvents such as water so that it could be used in the human body.

Resumen La química computacional realiza el modelado y el cálculo de propiedades fisicoquímicas que permiten comprender las diferentes interacciones moleculares a escala nanométrica en aplicaciones médicas como el diseño de sistemas de liberación controlada, por ejemplo. El modelo PM6 se utilizó para analizar metformina y glibenclamida. Primero se obtuvieron las propiedades energéticas como la energía libre de Gibbs y las entalpias. Los resultados mostraron la afinidad de ambos fármacos con el agua (glibenclamide: -7,96 y metformina: -11,49) debido a la formación de enlaces de hidrógeno que fueron verificados por las electronegatividades correspondientes al momento dipolar y al coeficiente de partición (Log P). Posteriormente, se determinaron las principales propiedades para el diseño de un sistema de liberación que usa el complejo metformina/glibenclamida en el hidrogel de quitosano. En este proceso se apreció que la energía libre de Gibbs (-2157,60 kcal/mol) determinó la estabilidad termodinámica de la adsorción. Además, el Log P (-25,82) indicó una solubilidad instantánea a través de la formación de enlaces de hidrógeno y se verificó mediante la distribución electrónica y el cambio en el momento dipolar.

Abstract Computational chemistry performs the modeling and calculation of physicochemical properties that allow understanding of the different molecular interactions at the nanometric scale in medical applications such as the design of controlled release systems. The PM6 model was used to analyze metformin and glibenclamide. First, the energy properties as the Gibbs free energy and enthalpies were obtained. The results showed the affinity of both drugs with water (glibenclamide: -7.96 and metformin: -11.49) due to the formation of hydrogen bonds, which were verified by the electronegativities corresponding to the dipole moment and to the partition coefficient (Log P). Subsequently, the main properties for the design of a release system using the metformin/glibenclamide complex in the chitosan hydrogel were determined. In this process it was appreciated that the Gibbs free energy (-2157.60 kcal/ mol) determined the thermodynamic stability of the adsorption. In addition, the Log P (-25.82) indicated an instantaneous solubility through the formation of hydrogen bonds and were verified by the electronic distribution and the change in dipole moment.

Resumo A química computacional realiza a modelagem e o cálculo das propriedades físico-químicas que permitem compreender as diferentes interações moleculares em escala nanométrica em aplicações médicas, como o projeto de sistemas de liberação controlada. O modelo PM6 é usado para analisar metformina e glibenclamida. Primeiro, obtenha as propriedades energéticas como a energia livre de Gibbs e as entalpias. Os resultados mostram a afinidade de ambos os componentes com água (glibenclamida: -7.96 e forma: -11.49) debitados na forma de ligações de hidrogénio, que verificam por eletronegatividades correspondentes no momento dipolar e coeficiente de participação (Log P). Posteriormente, selecione as principais propriedades para o projeto de um sistema de liberação que usa o método completo/glibenclamida no hidrogel de quitosano. Neste processo, aprecie a energia livre de Gibbs (-2157.60 kcal/mol) que determina a estabilidade termodinâmica da adsorção. Além disso, o Log P (-25.82) indica uma solução instantânea para a passagem de forma de hidrogénio e é verificada usando a distribuição eletrônica e o câmbio no momento dipolar.

The development of new fibrous composites with specific properties has attracted a big interest in the development of new technologies. One of the biggest problems in this area is the improvement of the fiber/matrix interface to increase the mechanical properties in the final composite. In this work, surface chemical modifications of the rice husk (by-product of the rice industry) were carried out to achieve a better compatibility with diverse polymeric matrices. These modifications include the use of three different silanes: 3-(trimethoxysilyl) propyl methacrylate (TMS), dichlorodimethylsilane (DDS) and trichlorovinylsilane (TVS). The natural fibers and their changes after each treatment were studied experimentally by Fourier Transformed Infrared Spectroscopy (FTIR). This experimental spectroscopic information was compared with a theoretical analysis of molecular vibrations using the Hyperchem Release 7 software as molecular modeling tool. The result of this comparison confirmed the chemical modification. It was concluded that the chemical modification was carried out and after an experimental spectroscopic analysis (FTIR) the molecular vibrations data were agree with those calculated by theoretical analysis being verified in this way the chemical modification of the rice-husk fiber surface. The successes of the synthesis of the cellulose with different silanes were confirmed with NMR.

El desarrollo de nuevos compuestos fibrosos con propiedades específicas ha atraído un interés grande en el desarrollo de nuevas tecnologías. Uno de los problemas más grandes en esta área es la mejora de la interface fibra/matriz para incrementar las propiedades mecánicas en el composito final. En este trabajo, la modificación química de la superficie de la cáscara del arroz (derivado de la industria del arroz) se llevó a cabo para lograr una mejor compatibilidad con matrices de diferentes polímeros. Estas modificaciones incluyen, el uso de tres diferentes silanos: 3-(trimetoxisilil) propil metacrilato (TMS), diclorodimetilsilano (DDS) así como, triclorovinilsilano (TVS). Las fibras naturales y los cambios después de cada tratamiento fueron estudiados experimentalmente mediante, Espectroscopia de Infrarrojo por Transformadas de Fourier (FTIR). Esta información experimental espectroscópica fue comparada con un análisis teórico de las vibraciones moleculares que se emplearon a través del software Hyperchem Release 7, herramienta de modelación molecular. El resultado de esta comparación confirmó la modificación química efectuada. Los datos de las vibraciones moleculares coincidieron con aquellos calculados por análisis teórico, los cuales comprobaron la modificación química de la superficie de fibra de arroz-cáscara. La síntesis de la celulosa con los silanos fueron confirmados por RMN.

The present work describes the synthesis and characterization of polyurethane (PU), polyaniline (PANI) and three IPNs (90/10, 80/20, 70/30) ratios were characterized by Fourier transformed infrared (FTIR) to analyze the generated functional groups of the synthesis. The combination PU/PANI was accomplished through the interconnection of the two polymers via condensation of PU prepolymer terminal NCO groups and the amine groups of PANI. DMA studies indicated that the PU had higher glass transition temperatures (Tg) with the increase of PANI. SEM micrographics were obtained to 1000X of the PU, PANI and the ratios 90/10, 80/20 and 70/30 of PU/PANI. A morphological interpretation was proposed in which PANI chains formed a phase dispersed in a PU matrix, linked together by an interphase, that could be responsible for the connectivity between the two polymers and determine excellent mechanical properties.

El presente trabajo describe la síntesis y caracterización del Poliuretano, (PU), Polianilina (PANI) y tres IPNs (90/10, 80/20, 70/30). Estos materiales fueron caracterizados mediante espectroscopia de infrarrojo por transformadas de Fourier (FTIR) para analizar los grupos funcionales generados de la síntesis. La combinación PU/ PANI se llevó a cabo a través de la interconexión de los dos polímeros vía condensación de grupos de NCO terminales del prepolímero de PU y las aminas de la PANI. Los estudios de DMA indicaron que el PU presentó temperaturas de transición vítreas (Tg) mayores con el incremento de PANI. Se obtuvieron las micrografías de SEM a 1000X del PU, PANI y las relaciones 90/10, 80/20 y 70/30 de PU/PANI, en donde, las cadenas de PANI formadas se dispersaron en la matriz de PU, se produjo una interfase, la cual fue la responsable de la conectividad entre los dos polímeros y determinaron excelentes propiedades mecánicas.