Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers.
Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers.
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DOI：
10.1021/acsami.6b00410
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发表时间：
2016-04
影响因子：
9.5
通讯作者：
Baolei Zhu;Rémi Mérindol;A. Benítez;Baochun Wang;A. Walther
中科院分区：
文献类型：
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作者：
Baolei Zhu;Rémi Mérindol;A. Benítez;Baochun Wang;A. Walther
天然复合物是由有序的胶体和分子长度尺度组合而成的分级结构。它们激发了未来的仿生和轻质纳米复合材料，通过理解和掌握分层结构形成作为工程多尺度变形机制的工具，可以实现非凡的机械性能。在这里，我们描述了一个分层自组装，纳米复合材料与定义良好的胶体为基础的螺旋结构和超分子氢键工程的分子水平上的聚合物基体。我们使用可逆加成-断裂转移聚合来合成具有不同功能化密度的4倍氢键脲基嘧啶酮（UPy）基序的定义明确的亲水性非离子聚合物。我们表明，这些共聚物可以与纤维素纳米晶体（CNC），一个可持续的，僵硬的，棒状的加强，给予有序的双相特性的光子阻带。螺旋节距的尺寸由聚合物/CNC的比率控制，从而确认平滑地整合到胶体结构中。相对于超分子图案的效果，我们证明了那些调节溶胀时，将仿生混合物暴露于水，他们允许工程的光子响应。此外，氢键的量和聚合物分数在限定机械性能方面是决定性的。阿什比图比较以前的有序的基于CNC的纳米复合材料与我们的新的分层显示，分子工程使我们能够跨越前所未有的机械性能范围，从最高的非弹性变形（应变高达13%）到最高的刚度（E 15 GPa）以及两者的组合。我们设想，分子相互作用的进一步合理设计将提供有效的工具，用于增强这种生物启发纳米复合材料的多功能特性。
Natural composites are hierarchically structured by combination of ordered colloidal and molecular length scales. They inspire future, biomimetic, and lightweight nanocomposites, in which extraordinary mechanical properties are in reach by understanding and mastering hierarchical structure formation as tools to engineer multiscale deformation mechanisms. Here we describe a hierarchically self-assembled, cholesteric nanocomposite with well-defined colloid-based helical structure and supramolecular hydrogen bonds engineered on the molecular level in the polymer matrix. We use reversible addition-fragmentation transfer polymerization to synthesize well-defined hydrophilic, nonionic polymers with a varying functionalization density of 4-fold hydrogen-bonding ureidopyrimidinone (UPy) motifs. We show that these copolymers can be coassembled with cellulose nanocrystals (CNC), a sustainable, stiff, rod-like reinforcement, to give ordered cholesteric phases with characteristic photonic stop bands. The dimensions of the helical pitch are controlled by the ratio of polymer/CNC, confirming a smooth integration into the colloidal structure. With respect to the effect of the supramolecular motifs, we demonstrate that those regulate the swelling when exposing the biomimetic hybrids to water, and they allow engineering the photonic response. Moreover, the amount of hydrogen bonds and the polymer fraction are decisive in defining the mechanical properties. An Ashby plot comparing previous ordered CNC-based nanocomposites with our new hierarchical ones reveals that molecular engineering allows us to span an unprecedented mechanical property range from highest inelastic deformation (strain up to ∼13%) to highest stiffness (E ∼ 15 GPa) and combinations of both. We envisage that further rational design of the molecular interactions will provide efficient tools for enhancing the multifunctional property profiles of such bioinspired nanocomposites.