The classical approach to prepare nanocomposites is often applied to chemical or physical modification of nanofillers to improve interfacial interaction between nanofillers and matrices. However, those methods might disturb the original reinforcement of nanoparticles due to the inhibition and even the absence of association among fillers. Here, we inspected a molecular design strategy using rod-like cellulose nanocrystals (CNCs) as fillers to study whether regulating the surface structure of CNC could allow a better reinforcement effect. Toward that, we prepared four modified CNCs by esterification with mono or binary anhydrides of different lengths of carbon chains. The long hydrocarbon chains were supposed to further improve the interfacial compatibility between CNC and poly(lactic acid) (PLA), and the terminal carboxyl groups should retain the association between nanoparticles. Results from transmittance of visible light for the nanocomposite films revealed homogeneous dispersion and good compatibility between modified nanocrystals and PLA matrix, especially for the long carbon-chain grafting CNCs. With an addition of 4 wt% dodecenyl succinic anhydride-modified CNC, the nanocomposite showed an increase in the tensile strength by ca. 170%. This was ascribed to the improved entanglement of grafting long chains and the potential interaction of terminal carboxyl groups on the CNC surface with the segments of PLA matrix, which enhanced association and compatibility between nanoparticles and matrix. This strategy prepared a biomass alloy of green materials reinforced by natural polymers and promoted the sustainable development of materials with high mechanical properties.

中文翻译：

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调节纤维素纳米晶体的表面分子结构，以优化对疏水性生物基聚酯的机械增强效果

制备纳米复合材料的经典方法通常应用于纳米填料的化学或物理改性，以改善纳米填料与基体之间的界面相互作用。但是，这些方法可能会由于抑制甚至导致填料之间不存在缔合而干扰纳米颗粒的原始增强。在这里，我们检查了使用棒状纤维素纳米晶体（CNC）作为填充剂的分子设计策略，以研究调节CNC的表面结构是否可以实现更好的增强效果。为此，我们通过用碳链长度不同的一元或二元酸酐酯化制备了四种改性的CNC。长烃链应该进一步改善CNC与聚乳酸（PLA）之间的界面相容性，并且末端羧基应保留纳米颗粒之间的缔合。纳米复合膜的可见光透射率结果表明，改性纳米晶体与PLA基质之间具有均匀的分散性和良好的相容性，特别是对于长碳链接枝CNC。通过添加4重量％的十二碳烯基琥珀酸酐改性的CNC，纳米复合材料显示出抗张强度提高了约10％。170％。这归因于接枝长链的缠结得到改善，以及CNC表面上末端羧基与PLA基质链段之间的潜在相互作用，从而增强了纳米颗粒与基质之间的缔合和相容性。