In this study, lactic acid monomer or dimer is grafted onto CNC by a simple esterification reaction. The quantitative solid-state ¹³C NMR spectrum suggests that more than 87% of all the available OH groups on the surface of CNC are substituted by lactic acid. Such modified CNC (CNC-g-LA) exhibits excellent thermostability and nano-sized dispersion in chloroform. Benefit from this character, fully biobased PLLA/CNC-g-LA nanocomposite could be prepared simply by a solution-casting method. The crystallization behavior of obtained nanocomposites has been systematically investigated by differential scanning calorimetry (DSC). The results show that the crystallization rate of PLLA is distinctly enhanced. Moreover, the mechanical properties of nanocomposites are also improved remarkably by the addition of CNC-g-LA because of its excellent dispersion and compatibility with PLLA matrix. This study provides a green and facile way to modify CNC for fabricating bio-nanocomposites with fast crystallization rate and improved mechanical properties.

在这项研究中，通过简单的酯化反应将乳酸单体或二聚体接枝到CNC上。定量固态¹³1 H NMR光谱表明，CNC表面上所有可用的OH基团中超过87％被乳酸取代。这种改性的CNC（CNC-g-LA）在氯仿中显示出优异的热稳定性和纳米级分散性。受益于此特性，可以完全通过溶液流延法制备全生物基PLLA / CNC-g-LA纳米复合材料。通过差示扫描量热法（DSC）已经系统地研究了获得的纳米复合材料的结晶行为。结果表明，PLLA的结晶速率明显提高。此外，由于其优异的分散性和与PLLA基质的相容性，通过添加CNC-g-LA，纳米复合材料的机械性能也得到了显着改善。