Hierarchical Self-Assembly and Chemical Imaging of Nanoscale Domains in Polymer Blend Thin Films
Hierarchical Self-Assembly and Chemical Imaging of Nanoscale Domains in Polymer Blend Thin Films
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聚合物共混薄膜中纳米级域的分层自组装和化学成像
DOI：
10.1021/acs.jpcc.2c01289
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Habteyes, Terefe G.
中科院分区：
文献类型：
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作者：
Tesema, Tefera E.;McFarland-Porter, Ross;Zerai, Epherem;Grey, John;Habteyes, Terefe G.
聚合物在分子间和分子内相互作用驱动下的自组装导致了聚合物共混物薄膜中丰富的结构变化。本工作利用散射型扫描近场光学显微镜研究了聚(3-己基噻吩基-2，5-二基)(P3HT)在聚(4-乙烯基吡啶)(P4VP)基质中形成纳米粒子的有序性和纳米粒子的自组装模式。当P3HT/P4VP/氯仿溶液在室温下旋转浇铸在未图案化的硅片上时，P3HT纳米粒子自发形成。我们发现，P3HT纳米粒子在P4VP基质中形成沿平行条纹的连续条纹，这取决于溶液的组成和旋涂的角速度。沿脊心平行的P3HT条纹之间的间距在4-12μm范围内随样品而变化，而限制在脊内的P3HT条纹的宽度由S红外相位差确定为0.20-1.1μm。P3HT纳米粒子的尺寸从5 nm到100 nm以上不等，这取决于共混物的组成，这是通过选择性溶解P4VP基质后使用原子力显微镜来确定的。我们实验中观察到的最小尺寸明显小于文献中报道的最小直径(大于20 nm)。结果表明，溶剂挥发过程中不相容聚合物之间的相互作用可以控制从分子有序性到介观尺度的分级自组装，而高分辨率的化学成像对于分辨纳米尺度的微区是必要的，从而可以优化溶液过程。
Self-assembly of polymers driven by intermolecular and intramolecular interactions leads to rich structural variations in thin films of polymer blends. In this work, ordering of poly(3-hexylthiophene-2,5-diyl) (P3HT) to form nanoparticles (NPs) and the self-assembly pattern of the NPs in poly(4-vinylpyridine) (P4VP) matrix are revealed by using scattering-type scanning near-field optical microscopy (s-SNOM). The P3HT NPs are formed spontaneously when the P3HT/P4VP/chloroform solution is spin-cast on unpatterned silicon wafer at room temperature. We find that the P3HT NPs organize within the P4VP matrix forming continuous stripes along the parallel striations, depending on the solution composition and spin-coating angular speed. The spacing between the parallel P3HT stripes that runs along the center of the ridges varies from sample to sample within 4–12 μm, whereas the width of the P3HT stripes confined within the ridges ranges from 0.2 to 1.1 μm as determined from the s-SNOM infrared phase contrast. The sizes of the P3HT NPs range from 5 to over 100 nm depending on the composition of the blend as determined by using an atomic force microscope after selectively dissolving the P4VP matrix. The smallest size observed in our experiment is significantly smaller than the smallest diameter (larger than 20 nm) reported in the literature. The results presented here show that interaction between immiscible polymers during solvent evaporation can be manipulated to control hierarchical self-assembly from molecular ordering to mesoscale dimensions, and high-resolution chemical imaging is necessary to resolve nanoscale domains so that solution processes can be optimized.