Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072, PR China; School of Material Science and Engineering, Tianjin University, Tianjin 300072, PR China.
Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072, PR China; School of Material Science and Engineering, Tianjin University, Tianjin 300072, PR China.
Int J Biol Macromol. 2021 Jun 30;181:621-630. doi: 10.1016/j.ijbiomac.2021.03.168. Epub 2021 Mar 30.
Spherical nanocelluloses, also known as cellulose nanospheres (CNS), have controllable morphology and have shown advantages as green template material, emulsion stabilizer. Herein, CNS were prepared via a new two-step method, first pretreatment of microcrystalline cellulose (MCC) using ZnCl·3HO and then acid hydrolysis of regenerated cellulose (RC) via p-toluenesulfonic acid (p-TsOH). The shape, size, crystallinity of MCC were changed, and nubbly RC with smallest size (942 nm) was obtained after 2 h pretreatment by ZnCl·3HO. CNS with high 61.3% yield were produced after acid hydrolysis (67 wt% p-TsOH) of RC at 80 °C, 6 h. The analysis of Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) showed that CNS had an average diameter of 347 nm. CNS were present in precipitate after high-speed centrifugation, due to the high Zeta potential of -12 mV and large size. The structure of CNS was tested by Fourier Transfer Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Nuclear Magnetic Resonance (NMR), CNS had high crystallinity (cellulose II) of 61%. Thermal Gravimetric Analysis (TGA) indicated that CNS had high thermal stability (T 303.3 °C, T 332 °C). CNS showed poor re-dispersibility in water/ethanol/THF, 1 wt% CNS could be dissolved in ZnCl·3HO. 7.37% rod-like CNC were obtained after 6 h hydrolysis. FTIR proved that p-TsOH was recovered by re-crystallization. This study provided a novel, sustainable two-step method for the preparation of spherical CNS.
球形纳米纤维素，也称为纤维素纳米球（CNS），具有可控的形态，并且作为绿色模板材料、乳液稳定剂具有优势。在此，通过两步法制备 CNS，首先使用 ZnCl·3HO 预处理微晶纤维素（MCC），然后使用对甲苯磺酸（p-TsOH）对再生纤维素（RC）进行酸水解。MCC 的形状、尺寸、结晶度发生变化，经 2 h ZnCl·3HO 预处理后，得到具有最小尺寸（942nm）的多结节 RC。在 80°C 下，将 RC 用 67wt%p-TsOH 进行 6 h 酸水解后，可得到产率为 61.3%的 CNS。动态光散射（DLS）、透射电子显微镜（TEM）分析表明，CNS 的平均直径为 347nm。由于 CNS 的 Zeta 电位为-12mV 且粒径较大，因此在高速离心后以沉淀形式存在。通过傅里叶变换红外光谱（FTIR）、X 射线衍射（XRD）、核磁共振（NMR）对 CNS 的结构进行了测试，CNS 具有 61%的高结晶度（纤维素 II）。热重分析（TGA）表明 CNS 具有较高的热稳定性（T 303.3°C，T 332°C）。CNS 在水/乙醇/THF 中再分散性较差，1wt%的 CNS 可溶解于 ZnCl·3HO。6 h 水解后可得到 7.37%的棒状 CNC。FTIR 证明 p-TsOH 通过重结晶得到回收。本研究为制备球形 CNS 提供了一种新颖、可持续的两步法。
