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Phase Behavior of Liquid Crystalline Chitin/Acrylic Acid Liquid Mixture

2003; American Chemical Society; Volume: 19; Issue: 4 Linguagem: Inglês

10.1021/la020764n

1520-5827

Thi Thi Nge, Naruhito Hori, Akio Takemura, Hirokuni Ono, Tsunehisa Kimura,

Electrowetting and Microfluidic Technologies

Phase behavior of a liquid crystalline chitin/acrylic acid liquid mixture was studied to fabricate a chitin-based composite with unique optical property. From a series of phase separation studies, we can evaluate the ternary phase diagram of a chitin microfibril, water, and acrylic acid monomer system. A suitable starting liquid crystalline chitin concentration to obtain anisotropic monophase over a range of acrylic acid concentration (up to 33 (w/w) %) was 14.62% (14−15%) by weight. At lower acrylic acid concentration range, crystalline microfibrillar fragments of chitin self-assembled to form upper isotropic phase and lower anisotropic liquid crystal phase at high enough concentration of chitin crystallites. The latter showed a characteristic chiral nematic order, a fingerprint-like texture. Above this chitin concentration and at higher acrylic acid concentration range, the system formed a monophasic stable flow-birefringence glassy phase, which displayed a nematic order. This phase occurred within a very limited range of chitin crystallites concentration of about 6.22−6.41%, which provides a clear-cut boundary between isotropic phase and anisotropic phase as well as a metastable frozen-in state between chiral nematic order and nematic order.