<br>通过轻质纳米 Bouligand 材料中的受控纳米结构增强韧性,Small

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通过轻质纳米 Bouligand 材料中的受控纳米结构增强韧性
Small ( IF 13.0 ) Pub Date : 2023-03-20 , DOI: 10.1002/smll.202207779
Zainab S Patel ₁ , Lucas R Meza ₂

Affiliation

纳米材料增强的性能使其成为先进高性能材料的吸引力，但它们在提高韧性方面的作用尚不清楚。制造方面的挑战通常会阻碍纳米材料成分的正确组织，而测试方法的不充分导致人们对小尺度韧性的了解不足。在这项工作中，通过创建由螺旋聚合物纳米纤维（纳米 Bouligand）制成的轻质材料，量化了纳米材料和纳米结构对韧性的各自作用。单向（

θ $\theta $

= 0°）和纳米布利刚光束（

θ $\theta $

= 2°–90°）采用双光子光刻技术制造，并设计为具有相对密度的微单边切口弯曲 (μ-SENB) 配置

\bar{ρ} $\overline \rho $

48% 到 81% 之间。实验证明了两种独特的增韧机制。首先，纳米聚合物纤维尺寸增强的延展性使 0° 单向梁的比断裂能增加了 70%。其次，通过层间纤维扭转产生的纳米级刚度不均匀性可阻止裂纹扩展，并将高密度纳米 Bouligand 材料的绝对断裂能量耗散提高 48%。这种尺寸增强的延展性和纳米级异质性作为共存增韧机制的证明揭示了纳米工程材料极大提高新一代先进材料机械弹性的能力。

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Toughness Amplification via Controlled Nanostructure in Lightweight Nano-Bouligand Materials

The enhanced properties of nanomaterials make them attractive for advanced high-performance materials, but their role in promoting toughness has been unclear. Fabrication challenges often prevent the proper organization of nanomaterial constituents, and inadequate testing methods have led to a poor knowledge of toughness at small scales. In this work, the individual roles of nanomaterials and nanoarchitecture on toughness are quantified by creating lightweight materials made from helicoidal polymeric nanofibers (nano-Bouligand). Unidirectional (

θ $\theta $

= 0°) and nano-Bouligand beams (

θ $\theta $

= 2°–90°) are fabricated using two-photon lithography and are designed in a micro-single edge notch bend (µ-SENB) configuration with relative densities

\bar{ρ} $\overline \rho $

between 48% and 81%. Experiments demonstrate two unique toughening mechanisms. First, size-enhanced ductility of nanoconfined polymer fibers increases specific fracture energy by 70% in the 0° unidirectional beams. Second, nanoscale stiffness heterogeneity created via inter-layer fiber twisting impedes crack growth and improves absolute fracture energy dissipation by 48% in high-density nano-Bouligand materials. This demonstration of size-enhanced ductility and nanoscale heterogeneity as coexisting toughening mechanisms reveals the capacity for nanoengineered materials to greatly improve mechanical resilience in a new generation of advanced materials.

更新日期：2023-03-20

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