用于光学谐振器和激光应用的聚合物微球的制造
Summary
提出了从聚合物合成微球的方法，微球的操作和微光致发光测量。
Abstract
本文介绍了三种制备包含π共轭或非共轭聚合物的荧光微球的方法：蒸气扩散，界面沉淀和微乳液。在所有方法中，精确定义的微米尺寸的球体是从溶液中的自组装过程获得的。蒸气扩散法可以产生具有最高球形度和表面平滑度的球体，但能够形成这些球体的聚合物的类型是有限的。另一方面，在微乳液法中，微球体可以由各种类型的聚合物制成，甚至由具有共面π共轭骨架的高结晶聚合物制成。来自单一分离的微球的光致发光（PL）性质是不寻常的：PL被限制在球体内部，通过聚合物/空气界面处的全内反射在球体的圆周处传播，并且自我干扰以显示清晰和周期性的共振PL线。这些共鸣g模式是所谓的“耳语画廊模式”（WGM）。这项工作演示了如何使用微光致发光（μ-PL）技术从单个孤立球体测量WGM PL。在该技术中，聚焦的激光束照射单个微球，并通过光谱仪检测发光。然后使用显微操作技术逐个连接微球，并且在一个球体的周边激发并且从另一个微球体检测PL的情况下，证明来自耦合的微球的球间PL传播和颜色转换。这些技术，μ-PL和显微操作，可用于使用聚合物材料的微光学应用的实验。
Introduction
聚合物纳米/微米粒子广泛用于各种应用，包括作为催化剂载体，柱层析填料，药物递送剂，用于细胞追踪的荧光探针，光学介质等。1,2,3,4,5 ， 6，7，8，9 。特别地，π共轭聚合物具有固有的发光和电荷导电性能，其有利于使用聚合物球10,11,12,13,14的光学，电子和光电子应用，特别是使用软组织的激光应用动物材料15,16,17 。例如，具有几百纳米直径的球体的三维集成形成胶体晶体，其在一定波长18,19处显示光子带隙。当光限制在星际周期结构中时，激光作用出现在阻带的中间。另一方面，当球体的尺寸增加到几微米尺度时，光通过聚合物/空气界面20处的全内反射被限制在单个微球内。在最大圆周处的光波的传播导致干扰，导致出现具有尖锐和周期性发射线的谐振模式。这些光学模式是所谓的“耳语画廊模式”（WGM）。术语“耳语画廊”起源于在伦敦的圣保罗大教堂，声波沿着墙壁的周围传播，让画廊另一边的人听到耳语。因为光的波长在远小于声波的亚微米尺度上，所以这样大的圆顶对于光的WGM是不必要的：微小的，微米级的，明确的容器，例如微球，微盘和微晶，满足WGM条件。
等式1是WGM谐振条件21的简单形式：
nπd = lλ （1）
其中n是谐振器的折射率， d是直径， l是整数， λ是光的波长。 （1）的左边部分是通过一个圆形传播的光程长度。当光路重合时发生波长的整数倍，发生共振，而在另一波长处，光波在四舍五入时减小。
本文介绍了几种用于制备溶液中共轭聚合物的WGM共振器的微球的实验方法：蒸气扩散22,23,24,25,26,27,28,29,30，微乳液31和界面沉淀32 。每种方法都有独特的特征;例如，蒸气扩散方法提供了非常高的球形度和光滑表面的明确定义的微球体，但只有低结晶度聚合物可以形成这些微球体。另一方面，对于微乳液方法，各种共轭聚合物（包括高结晶聚合物）可以形成球体，但是表面形态不如从蒸气扩散法得到的。从染料掺杂的非共轭聚合物制备微球体，界面析出法是优选的。在所有情况下，溶剂和非溶剂的选择在球形形态的形成中起重要作用。
在本文的下半部分，介绍了μ-PL和微操作技术。对于μ-PL技术，微球分散在基底上，并且通过显微镜透镜聚焦的激光束用于照射单个分离的微球24 。通过显微镜透镜由光谱仪检测来自球体的生成的PL。移动样品台可以改变激发点的位置。检测点也可以通过倾斜exci的准直器光学元件而变化相对于检测路径28,32的光轴的激光束。为了研究球间光传播和波长转换，可以使用微操作技术32 。为了连接具有不同光学性质的几个微球体，可以使用微针拾取一个球体并将其放在另一个球体上。结合微操作技术和μ-PL方法，可以使用通过简单的自组装方法制备的共轭聚合物球进行各种光学测量。该视频文件对于希望使用软质聚合物材料用于光学应用的读者将是有用的。
Protocol
Representative Results
Discussion
The selection of a good solvent and non-solvent is very important for the self-assembly of well-defined microspheres. If the solubility of a polymer is too high, precipitation will not occur. Also, in general, π-conjugated polymers are hydrophobic, so polar non-solvents, such as MeOH, acetonitrile, and acetone, are often used in the vapor diffusion method to minimize the surface energy required to form a spherical shape. The interface precipitation method is often adopted for the preparation of dye-doped polymer mic…
Disclosures
The authors have nothing to disclose.
Acknowledgements
这项工作得到JSPS / MEXT日本，朝日玻璃基金会和筑波大学前战略倡议“光与事物与生活的合奏”的KAKENHI（25708020,15K13812,15H00860，15H00986，16H02081）的部分支持。
Materials
| polystyrene | Aldrich | 132427-25G | |
| sodium dodecylsulfate | Kanto Kagaku | 372035-31 | |
| tetrahydrofuran | Wako | 206-08744 | |
| chloroform | Wako | 038-18495 | |
| methanol | Wako | 139-13995 | |
| Poly(9,9-di-n-octylfluorenyl-2,7-diyl) | Aldrich | 571652-500MG | |
| Poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMOPPV) | Aldrich | 546461-1G | |
| poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(5-octylthieno[3,4-c]pyrrole-4,6-dione-1,3-diyl)] (P1) | synthesized | – | reference 28 |
| poly[(N-(2-heptylundecyl)carbazole-2,7-diyl)-alt-(4,8-bis[(dodecyl)carbonyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)] (P2) | synthesized | – | reference 28 |
| fluorescent dye (boron dipyrrin; BODIPY) | synthesized | – | reference 32 |
| Optical Microscope | Nicon | Eclipse LV-N | |
| laser_405 nm | Hutech | DH405-10-5 | |
| laser_355 nm | CNI | MPL-F-355-10ｍW | |
| Spectrometer | Lambda Vision | LV-MC3/T | |
| Homogenizer | Microtech Nichion | Physcotron NS-360D | |
| micromanipulation | Microsupport | Quick Pro QP-3RH |
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