Effect of the drying on morphology and texture of aerogels and zirconia cryogels
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.450
Effect of the drying on morphology and texture of aerogels and zirconia cryogels Tzipatly A. Esquivel-Castro1, Antonia Martínez-Luévanos1*, Luis Alfonso García-Cerda2, Juan C. Contreras-Esquivel1, Pascual Bartolo Pérez3, Elsa Nadia Aguilera González1 1 Departamento de Materiales Cerámico Avanzados y Energía, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, 25280, Saltillo, Coahuila, México
2
Centro de Investigación en Química Aplicada, 25294, Saltillo, Coahuila, México
3
Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional-Unidad Mérida, 97310, Mérida, Yucatán, México
ABSTRACT
Due to their excellent properties, aerogel has attracted the attention of the scientific community to use it in the biomedical area as a drug delivery system. This work reports on the synthesis and characterization of ZrO2 aerogels and cryogels obtained by the sol-gel method. The influence of different cetyltrimethylammonium bromide (CTAB) and the type of drying on structural, morphological and texture properties of ZrO2 aerogels and cryogels was investigated. SEM images reveal that a porous interconnected three-dimensional network was formed into aerogels due to supercritical drying. Zirconia aerogel sample has a specific surface area (SBET) larger than zirconia cryogels. Therefore, our results indicate that zirconia aerogel is an adequate material for applications in drug delivery systems.
1. INTRODUCTION Nowadays, the aerogel is an exceptional material that is very light and porous, composed of an interconnected three-dimensional network of open pores (in the order of mesopores and macropores). That is why, approximately 95% of its volume is constituted by air, while the remaining 5% is solid [1, 2]. On the other hand, it has properties such as low density (0.001-0.5 g/cm3), large surface area (100-1600 m2/g), low thermal conductivity (0.02 W/m K), high porosity (80%-99.8%) and low refractive index
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(1.007-1.24) [1-3]. Due to their excellent properties, they have attracted the attention of the scientific community to use it in applications such as thermal insulation, sensor, catalysis, absorbent, and more recently in the biomedical area as a drug delivery system [3-6]. The most important stage of the aerogel formation process is drying, so the supercritical drying has been one of the most widely used techniques to prevent shrinking and collapse of the aerogel structure, because the supercritical fluid under supercritical conditions has an almost zero surface tension. Therefore, it prevents the liquid-vapor interface from forming inside the pore, keeping the three-dimensional network intact. Compared to supercritical drying, freeze-drying i
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