Synthesis of hyperbranched fluorinated polymers with controllable refractive indices
Synthesis of hyperbranched fluorinated polymers with controllable refractive indices
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DOI：
10.1038/pj.2010.134
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发表时间：
2011-03
期刊：
影响因子：
2.8
通讯作者：
M. Miyasaka;N. Koike;Yusuke Fujiwara;Hiroto Kudo;T. Nishikubo
中科院分区：
文献类型：
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作者：
M. Miyasaka;N. Koike;Yusuke Fujiwara;Hiroto Kudo;T. Nishikubo
与碳氢化合物类似物相比，含有氟原子的聚合物（氟化聚合物）表现出更高的热稳定性、疏水性、更好的耐化学性和更低的分子间吸引力。这些性质源于氟的基本原子性质，如高电离电位、低极化率和高电负性。高电离电位加上低极化率，导致分子间相互作用弱，从而导致含氟聚合物的低表面能和低折射率。近年来，含氟聚合物作为高性能材料在光电领域的应用受到了广泛的关注。具体来说，折射率是光子应用中聚合物的一个非常重要的特性，其中高氟化聚合物如特氟龙（杜邦，威尔明顿，DE，美国）和CYTOP（旭硝子玻璃有限公司，日本东京）是众所周知的，并广泛用于光通信网络。目前的光通信网络主要是基于二氧化硅光纤和器件。为了与这些器件和材料集成，并减少光学损耗，需要折射率值接近二氧化硅材料（1.46）的聚合物材料。2因此，成功设计和制造光子器件需要具有可控折射率的材料。例如，广泛使用的氟化聚酰亚胺通常具有相对较低的折射率3，通过引入极性基团并与含有较重原子的共聚单体（如溴）共聚，可以很容易地控制这一数值，从而获得较高的折射率。然而，降低折射率似乎很困难。我们在季铵盐的存在下，用双（环氧化物）s与二羧酸和二醇的简单多加成改性了含氟聚合物，它们在折射率和聚合物的氟含量之间表现出线性关系。4,5对氟化芳族脂肪共聚醚、6氟化聚（酞嗪酮醚）7和超支化氟化聚酰亚胺也进行了类似的研究。8聚合物的折射率（nD）、密度（rg cmÀ3）、分子量（mg molÀ1）和分子折射率（R cm3 molÀ1）之间的关系由洛伦兹-洛伦兹方程（式1）描述
INTRODUCTION Polymers containing fluorine atoms (fluorinated polymers) exhibit increased thermal stability, hydrophobicity, improved chemical resistance and decreased intermolecular attractive forces in comparison with their hydrocarbon analogs. These properties are derived from the fundamental atomic properties of fluorine, such as high ionization potential, low polarizability and high electronegativity. 1 The high ionization potential, combined with the low polarizability, leads to weak intermolecular interactions, which in turn leads to low-surface energy and low refractive indices of fluorinated polymers. Recently, fluoropolymers have received considerable attention as high-performance materials for applications in optoelectronic fields. Specifically, the refractive index is a very important property of polymers for photonic applications, for which highly fluorinated polymers such as Teflon (DuPont, Wilmington, DE, USA) and CYTOP (ASAHI GLASS CO., LTD., Tokyo, Japan) are well known and widely used in optical communication networks. Current optical communication networks are based on silica optical fiber and devices. To integrate with these devices and materials, and to reduce the optical loss, polymer materials with refractive index values close to that of the silica materials (1.46) are desired. 2 Therefore, materials with a controllable refractive index are required for the successful design and fabrication of photonic devices. For example, the widely used fluorinated polyimides usually have relatively low refractive indices 3 and this value can be easily manipulated by introducing polar groups and copolymerizing with comonomers containing heavier atoms, such as bromine to give high refractive indices. However, it appears difficult to lower the refractive index. We have modified fluoropolymers with the simple polyaddition of bis (epoxide) s with dicarboxylic acids and diols in the presence of quaternary onium salts and they exhibited a linear relationship between refractive indices and fluorine contents of the polymer. 4, 5 Similar investigations have been conducted with fluorinated aromatic–aliphatic copolyethers, 6 fluorinated poly (phthalazinone ether) s 7 and hyperbranched fluorinated polyimides. 8 The relationship between the refractive index (nD), density (rg cmÀ3), molecular weight (M g molÀ1) and molecular refraction (R cm3 molÀ1) of a polymer is described by the Lorentz–Lorenz equation (Equation 1). 9 nD ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi M+ 2rR