Lyotropic liquid crystal behavior of carboxylated cellulose nanocrystals.
In this work, the lyotropic liquid crystal (LC) behavior of carboxylated cellulose nanocrystals (CNs) has been studied for cotton cellulose prepared by TEMPO-mediated oxidation of cellulose nanocrystals (TOCNs). It is found that suspensions of TOCNs at a critical concentration of 4.1wt% form anisotropic phase with clear optical birefringence. Furthermore, fingerprint texture is clearly observed when the concentration is 9.0wt% under a polarizing optical microscope. Fingerprint texture is characteristic of chiral nematic liquid crystal (N*-LC) phase. The band-spacing corresponds to half the helical pitch, and thus, the helical pitch of N*-LCs (9.0wt%) is about 6.0μm. The degree of oxidation (DO) and zeta potential of TOCNs in suspension are 0.15 and -59.5mV, respectively. Relatively larger aspect ratio and higher surface charges density of TOCNs make the critical concentration of LC formation decreased and the helical pitch increased compared to that of the LC prepared by H2SO4hydrolysis system. The interparticle electrostatic repulsion between CNs with different surface charges influence the helical pitch of N*-LCs.
Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science & Technology (QUST), Qingdao 266042, China; Shandong Provincial Key Laboratory of Rubber-Plastics, QUST, Qingdao 266042, China; School of Polymer Science and Engineering, QUST, Qingdao 266042, China.
Jintao
J
He
Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science & Technology (QUST), Qingdao 266042, China; Shandong Provincial Key Laboratory of Rubber-Plastics, QUST, Qingdao 266042, China; School of Polymer Science and Engineering, QUST, Qingdao 266042, China.
Sitong
S
Liu
Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science & Technology (QUST), Qingdao 266042, China; Shandong Provincial Key Laboratory of Rubber-Plastics, QUST, Qingdao 266042, China; School of Polymer Science and Engineering, QUST, Qingdao 266042, China.
Ling
L
Li
Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science & Technology (QUST), Qingdao 266042, China; Shandong Provincial Key Laboratory of Rubber-Plastics, QUST, Qingdao 266042, China; School of Polymer Science and Engineering, QUST, Qingdao 266042, China. Electronic address: piao@qust.edu.cn.
Guangzhe
G
Piao
Chiral interaction; Critical concentration; Helical pitch; N*-LCs; TEMPO oxidation