دانلود رایگان مقاله سلولز متخلخل و قالب آزاد ساختگی، مورفولوژی - قابل تنظیم

Abstract

Recently, monoliths with continuous porous structure have received much attention for high-performance separation/adsorption matrix in biomedical and environmental fields. This study proposes a novel route to prepare cellulose monoliths with hierarchically porous structure by selecting cellulose acetate (CA) as the starting material. Thermally induced phase separation of CA solution using a mixed solvent affords a CA monolith, which is converted into the cellulose monolith by alkaline hydrolysis. Scanning electron microscopy images of the CA and cellulose monoliths reveal a continuous macropore with rough surface, and nitrogen adsorption/desorption analysis indicates the formation of a mesoporous structure. The macroporous structure could be controlled by changing the fabrication parameters. A series of reactive groups are introduced by chemical modifications on the surface of the cellulose monolith. The facile and diverse modifiability combined with its hydrophilic property make the hierarchically porous cellulose monolith a potential platform for use in separation, purification and bio-related applications.

4. Conclusions

A hierarchically porous cellulose monolith exhibiting high hydrophilicity and tolerance toward common solvents was readily fabricated from a CA solution by TIPS. A mixed solvent of 1-hexanol and DMF in the appropriate mixed ratio provided the CA monolith with a 3D continuous macroporous structure in a columnar shape. BET analysis revealed the formation of a uniform mesopore of 11.2 nm. The phase separation parameters including the polymer concentration, molecular weight of CA, and ratio of 1-hexanol/DMF greatly affected the skeleton size and inner morphology of the CA monolith. The alkaline hydrolysis of the CA monolith in methanol selectively proceeded to give the cellulose monolith, and the shape and morphology hardly changed after the hydrolysis. Typical reactive groups, epoxy, primary amine, and aldehyde, were introduced on the skeleton surface of the cellulose monolith. Cellulose-based matrices are useful for the separation of biorelated molecules such as antibodies, protein drugs, DNA, and SiRNA. Therefore, a variety of studies on fabrication techniques, shape and morphology control, and the introduction of ligands, have been extensively developed (Carrillo et al., 2014; Gericke et al., 2013; Hosoda et al., 2014; Joshi et al., 2016; Nguyen et al., 2013; Wang et al., 2016). The present cellulose monolith possessed several features such as easy chemical modification, high solvent efficient mass transfer, large surface area, high stability, and high mechanical strength as a result of the cmonolithic and hierarchically porous structure as well as characteristic properties of cellulose. Therefore, the cellulose monolith and its reactive derivatives have great potential for the efficient separation of bio-related molecules. Further studies on the fabrication and applications of protein-loading cellulose monoliths are currently in progress in our laboratory.