School of Material Science and Engineering, and National Engineering Laboratory of Textile Fiber Materials and Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Zhejiang Provincial Innovation Center of Advanced Textile Technology, Shaoxing 312000, China.
Langmuir. 2023 Jul 18;39(28):9857-9864. doi: 10.1021/acs.langmuir.3c01070. Epub 2023 Jul 10.
Titanium dioxide (TiO) nanoparticles have been extensively used to modify the optical properties of various types of materials. In particular, they have been intensively loaded onto polymer fibers to quench the light reflection. In situ polymerization and online addition are two common strategies for fabricating TiO-loaded polymer nanocomposite fibers. The former does not require separate preparation of masterbatches as the latter does and therefore has its advantages in terms of decreasing the fabrication steps and economic costs. Moreover, it has been found that in situ-polymerized TiO-loaded polymer nanocomposite fibers (e.g., TiO/poly(ethylene terephthalate) fibers) usually have enhanced light-extinction properties over those prepared by the online addition process. Intuitively, there should be a difference in the filler particle dispersion for the two fabrication processes. This hypothesis has not yet been tackled due to the technical difficulty in acquiring the three-dimensional (3D) filler morphology inside the fiber matrix. In this paper, we report a study using the powerful focused ion beam-scanning electron microscopy (FIB-SEM) with a resolution of 20 nm to directly acquire the 3D microstructure of TiO/poly(ethylene terephthalate) nanocomposite (TiO/PET) fibers. This microscopy technique allows us to characterize the particle size statistics and the dispersion inside TiO/PET fibers. We have found that the particle size of TiO inside the fiber matrix can be well modeled by Weibull statistics. Surprisingly, we find that TiO nanoparticles form more significant agglomeration in the in situ-polymerized TiO/PET fibers. This observation is contrary to our common understanding of the two fabrication processes. Namely, slightly altering the particle dispersion with increased TiO filler size helps improve the light-extinction properties. The slightly increased filler size may have altered the Mie scattering between the nanoparticles and the incident visible light, leading to enhanced light-extinction properties of in situ-polymerized TiO/PET nanocomposite fibers.
二氧化钛（TiO）纳米粒子已被广泛用于修饰各种类型材料的光学性质。特别是，它们已被大量负载到聚合物纤维上以猝灭光反射。原位聚合和在线添加是制备 TiO 负载聚合物纳米复合材料纤维的两种常见策略。前者不需要像后者那样单独制备母粒，因此在减少制造步骤和经济成本方面具有优势。此外，已经发现，与通过在线添加过程制备的 TiO 负载聚合物纳米复合材料纤维（例如，TiO/聚对苯二甲酸乙二醇酯纤维）相比，原位聚合的 TiO 负载聚合物纳米复合材料纤维通常具有增强的光消光性能。直观地说，对于这两种制造工艺，填充颗粒的分散应该存在差异。由于在纤维基质内获得三维（3D）填充形态的技术难度，该假设尚未得到解决。在本文中，我们报告了一项使用强大的聚焦离子束扫描电子显微镜（FIB-SEM）的研究，该显微镜的分辨率为 20nm，可以直接获取 TiO/聚对苯二甲酸乙二醇酯（TiO/PET）纳米复合材料（TiO/PET）纤维的 3D 微观结构。这种显微镜技术使我们能够对颗粒尺寸统计和 TiO/PET 纤维内部的分散进行特征化。我们发现，纤维基质内 TiO 的颗粒尺寸可以通过威布尔统计进行很好的建模。令人惊讶的是，我们发现，在原位聚合的 TiO/PET 纤维中，TiO 纳米颗粒形成了更明显的团聚。这一观察结果与我们对这两种制造工艺的普遍理解背道而驰。也就是说，稍微改变颗粒分散性，增加 TiO 填充剂的尺寸，有助于提高光消光性能。稍微增加的填充剂尺寸可能改变了纳米颗粒与入射可见光之间的 Mie 散射，从而导致原位聚合的 TiO/PET 纳米复合材料纤维的光消光性能增强。
