Abstract
Cellulose aerogels (CAs) from plant or bacterial-derived cellulose have advantages such as low density, high porosity, and high specific surface area and have been used in various applications including biomedical fields. One limiting factor in developing CAs is their demanding shaping process since it involves several steps of dissolution/dispersion of cellulose, geometry configurations using molds or nozzles, coagulation and washing of the gel body, and drying techniques. CA fibers can be converted into textiles and enhance the design ability, stiffness, and flexibility of the CAs. This study aims to understand the correlations between the initial cellulose characteristics, aerogel’s internal structure, and its prospective biomedical application. Wet-spun CA fibers were obtained by supercritical CO2 drying from low and high molecular weight microcrystalline cellulose in calcium thiocyanate tetrahydrate solution. Fiber spinning, thermal behavior, textural properties, and biological assessments of the CA fibers were inspected. The CA microfibers from high molecular weight cellulose proved to have a higher surface area (~197 m2/g), denser structure, and finer nanofibrils (~2 nm) with better thermal stability in comparison with the fibers produced from low molecular weight cellulose. The fibers were nontoxic, and cell proliferation was observed over time. CA fibers showed promising results to be used for biomedical applications such as tissue engineering and wound care.
Highlights
Aerogels are open pores nanostructured solid networks with high porosity, high specific surface area, and low density [1]
The number average molecular weight (Mn), weight average molecular weight (Mw), z-average molecular weight, and polydispersity or heterogeneity index results from cellulose powder samples are shown in Figure 1 and Table 1
The higher molecular weight of cellulose type S (Cs) led to a 10 min longer dissolution time in the salt melt hydrate compared to the crystalline initial cellulose (Cc)
Summary
Aerogels are open pores nanostructured solid networks with high porosity, high specific surface area, and low density [1]. Aerogels are versatile porous materials with tunable textural and morphological characteristics for various fields such as adsorption and separation of materials, thermal insulation, and biomedical application [2,3,4]. Aerogels morphological characteristics are controllable with various processing parameters such as gelation, shaping, drying, and functionalization [3,5]. The drying process of precursor gel aims plays an important role in aerogel fabrication in order to retain 3D porous structure with minimal shrinkage and deformation. Freeze drying and supercritical CO2 (sCO2 ) drying have been widely used in cellulose aerogel (CAs) production; recently ambient pressure drying methods that require physical and chemical modification of the gels have been studied [8,9]. Typically sCO2 dried CAs show better textural and minimal shrinkage in contrast to other drying
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