Size Distribution and Characteristics of Chitin Microgels Prepared via Emulsified Reverse-Micelles

• Published in: Materials
• Main Authors: Siriporn Taokaew, Mitsumasa Ofuchi, Takaomi Kobayashi
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: crab shell; chitin; spherical microgels; reverse micelle; gelation; Technology; T; Electrical engineering. Electronics. Nuclear engineering; TK1-9971; Engineering (General). Civil engineering (General); TA1-2040; Microscopy; QH201-278.5; Descriptive and experimental mechanics; QC120-168.85; Snow crab
• Online Access: https://doi.org/10.3390/ma12071160; https://doaj.org/article/74852131019941e89fd31f8017f6eb77

Chitin was extracted from local snow crab shell waste and used as a raw material in the fabrication of porous spherical microgels. The chitin microgels were obtained using a batch process of emulsification and, afterward, gelation. The effects of chitin concentrations, oil and water phase ratios (O:W), surfactants, and gelation on the size distribution and morphology of the microgels were investigated. The extracted chitin possessed α-chitin with a degree of acetylation of ~60% and crystallinity of 70%, as confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Powder Diffraction (XRD). In the reverse-micellar emulsification, different chitin concentrations in NaOH solution were used as aqueous phases, and n-hexane media containing Span 80-based surfactants were used as dispersion phases. Various HCl solutions were used as gelling agents. Microgels with sizes ranging from ~5–200 μm were obtained relying on these studied parameters. Under the condition of 3% w / w chitin solution using O:W of 15:1 at 5% w / w of Span 80 (hydrophilic-lipophilic balance; HLB of 4.3), the gelation in the emulsified reverse micelles was better controlled and capable of forming spherical microgel particles with a size of 7.1 ± 0.3 μm, when 800 μL of 1 M HCl was added. The prepared chitin microgel exhibited macro-pore morphology and swelling behavior sensitive to the acidic pH.