Synthesis of porous templates using cellulose microfibers modified with phosphate groups

Synthesis of porous templates using cellulose microfibers modified with phosphate groups
C. R. Grizottoa C. A. Bertanb
a Undergraduate, Institute of Chemistry, UNICAMP, Brazil.
b Associate Professor, Institute of Chemistry, UNICAMP, Brazil.
[email protected]
Phosphate modified cellulose microfibers dispersions can undergo self-organization when submitted to centrifugation and lyophilization, resulting in 3D organized structures. The 3D organization was driven by the repulsion among the microfibers’ negative charge, the “g” force of centrifugation and the fiber exclusion in the freezing step of lyophilization. This kind of structures can be used as a template to synthesis of porous materials. In this work, cellulose microfibers modified with phosphate groups were prepared by the hydrolysis of pure cellulose with concentrated (14molL-1) hydrochloric acid [1], and modified by the reaction with metaphosphoric acid [2]. The cellulose hydrolysis with HCl results in microfibers with large surface that allowed an effective modification with phosphate groups. Figure 1 shows the size distribution of the microfibers prepared by 4 and 24 hours hydrolysis. The longer time hydrolysis produced higher volume in the 0.1 - 0.3 µm size range, while the shorter one favors fibers around 10 µm. The lesser sized fibers have also higher superficial area, which directly favors more effective superficial modifications. The reaction of phosphate modified microfibers with calcium ions allowed determining the phosphate present in the microfibers as 6.2 x 10-3 mol/g.
[1].Cheng, Miao; Quin Zongyi; Chen, Yuanyu; Hu, Shuo; Ren, Zichu; Zhu, Meifang. Efficient Extraction of Cellulose Nanocrystals through Hydrochloric Acid Hydrolysis Catalyzed by Inorganic Chlorides under Hydrothermal Conditions. ACS Sustainable Chem. Eng. 2017.
[2] Michael R. Mucalo, Katsuya Kato, Yoshiyuki Yokogawa. Phosphorylated, cellulose-based substrates as potential adsorbents for bone morphogenetic proteins in biomedical applications: A protein adsorption screening study using cytochrome C as a bone morphogenetic protein mimic. Colloids and Surfaces B: Biointerfaces, Volume 71, 52-58, 2009.