Ionic Liquids Grafted Cellulose Nanocrystals for High-Strength and Toughness PVA Nanocomposite
Ionic Liquids Grafted Cellulose Nanocrystals for High-Strength and Toughness PVA Nanocomposite
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离子液体接枝纤维素纳米晶体用于高强度和韧性 PVA 纳米复合材料
DOI：
10.1021/acsami.0c11217
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发表时间：
2020-08-26
影响因子：
9.5
通讯作者：
Zhang, Jianming
中科院分区：
文献类型：
--
作者：
Wang, Li;Hu, Jie;Zhang, Jianming
纤维素纳米晶的表面功能化对促进其多样化应用具有重要意义。然而，由于阳离子改性剂和电负性CNC之间的静电吸引力，迄今报道的用于CNC的阳离子官能化的有效策略仍然有限。本文以乳酸（LA）为连接分子，将离子液体[VBIm] [BF 4]接枝到硫酸化CNC表面，在水溶液中成功制备了阳离子化CNC（CNC-LA-IL）。这种表面官能化不仅将CNC悬浮液的负电荷转化为正电荷（ζ电位从-35 mV反转至+40 mV），而且还导致干燥CNC的热稳定性和再结晶性增强。为了考察IL改性CNCs的增强效果，进一步通过溶液浇铸法制备了聚乙烯醇（PVA）/CNC-LA-IL纳米复合膜。令人惊讶的是，所制备的PVA/CNC-LA-IL膜在仅0.3wt% CNC负载的情况下表现出拉伸强度（92%）和韧性（166%）的显著改善。本研究为离子液体接枝纳米碳纤维制备高性能纳米复合材料提供了一种绿色、简便的方法。
The surface functionalization of cellulose nanocrystals (CNCs) is of significant importance for promoting its diverse applications. However, the efficient strategy reported so far for cation functionalization of CNCs remains limited owing to the electrostatic attraction between cationic modifiers and electronegative CNCs. Herein, a cationized CNC (CNC-LA-IL) has been successfully prepared in aqueous media by grafting the [VBIm] [BF4], a kind of ionic liquid (IL), on the surface of a sulfated CNC using lactic acid (LA) as a linker molecule. This surface functionalization not only converts the negative charge of CNC suspensions to a positive charge (zeta potential reversed from -35 to +40 mV) but also leads to enhanced thermal stability and redispersibility of the dried CNC. To examine the reinforcing effect of IL-modified CNCs, poly(vinyl alcohol) (PVA)/CNC-LA-IL nanocomposite films were further prepared by the solution casting method. To one's surprise, the as-prepared PVA/CNC-LA-IL films exhibit extraordinary improvement in both the tensile strength (92%) and the toughness (166%) with only a 0.3 wt % CNC loading. This study provides a green and facile method to achieve ionic liquids grafted CNCs for high-performance nanocomposites.