Chen Po-Yen, Hung Hua-Li, Han Chien-Chung, Chiu Hsiang-Chih
Department of Physics, National Taiwan Normal University, Taipei, Taiwan 106, Republic of China.
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 300, Republic of China.
Langmuir. 2020 Apr 21;36(15):4153-4164. doi: 10.1021/acs.langmuir.0c00100. Epub 2020 Apr 8.
The correlation between structural order, elasticity, and semiconductivity for butylthio-functionalized polyaniline (PANI-SBu) thin films was investigated using atomic force microscopy (AFM)-based techniques with X-ray diffraction (XRD) and scanning electron microscopy (SEM). After different stirring times, the thin films were cast from the solution of PANI-SBu in -methyl-2-pyrrolidone that was continuously stirred at a constant rate of 150 rpm in an airtight round-bottom flask. According to the XRD and SEM results, the cross-sectional film structure evolved from being generally holey to highly lamellar with an increase in the stirring time. However, some new types of disordered structures began emerging beyond the optimal stirring time, possibly caused by the formation of disordered packing structures as contributed from the overoxidized polyaniline backbones during the additional stirring time. Moreover, according to the investigation results obtained using AFM-based techniques, the out-of-plane elastic moduli and charge mobilities of the PANI-SBu films were consistently smaller for disordered thin films and larger for structurally more ordered ones. The shear force resulting from the mechanical stirring of the PANI-SBu solution may gradually disentangle the polymer chains and thus help transform the individual polyaniline molecule from a coil-like chain conformation to a better extended rodlike chain conformation. Therefore, when cast into a film, the stretched polymer chains facilitate self-organization among the PANI-SBu backbones during the film formation process. Thus, an improved structural order in the film is attained. Our results demonstrate an unambiguous correlation between the structure order, elasticity, and conductivity in PANI-SBu thin films, which may have useful applications in conducting polymer-based flexible electronics.
采用基于原子力显微镜（AFM）的技术结合X射线衍射（XRD）和扫描电子显微镜（SEM），研究了丁硫基官能化聚苯胺（PANI-SBu）薄膜的结构有序性、弹性和半导体性之间的相关性。在不同的搅拌时间后，将薄膜从PANI-SBu在N-甲基-2-吡咯烷酮中的溶液浇铸而成，该溶液在密闭的圆底烧瓶中以150 rpm的恒定速率持续搅拌。根据XRD和SEM结果，随着搅拌时间的增加，薄膜的横截面结构从一般多孔状演变为高度层状。然而，在超过最佳搅拌时间后，一些新型的无序结构开始出现，这可能是由于在额外的搅拌时间内，过度氧化的聚苯胺主链形成了无序堆积结构所致。此外，根据基于AFM技术获得的研究结果，无序薄膜的PANI-SBu薄膜的面外弹性模量和电荷迁移率始终较小，而结构更有序的薄膜则较大。PANI-SBu溶液的机械搅拌产生的剪切力可能会逐渐解开聚合物链，从而有助于将单个聚苯胺分子从卷曲状链构象转变为更好的伸展棒状链构象。因此，当浇铸成薄膜时，拉伸的聚合物链在薄膜形成过程中促进了PANI-SBu主链之间的自组装。从而在薄膜中获得了改善的结构有序性。我们的结果表明PANI-SBu薄膜的结构有序性、弹性和导电性之间存在明确的相关性，这可能在基于导电聚合物的柔性电子学中有有用的应用。
