Paleti Sri Harish Kumar, Haraguchi Shuichi, Cao Zhiqiang, Craighero Mariavittoria, Kimpel Joost, Zeng Zijin, Sowinski Przemyslaw, Zhu Di, Pons I Tarrés Judith, Kim Youngseok, Li Qifan, Huang Junda, Kalaboukhov Alexei, Mihiretie Besira, Fabiano Simone, Gu Xiaodan, Müller Christian
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Göteborg , Sweden.
School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States.
Macromolecules. 2025 Mar 19;58(7):3578-3588. doi: 10.1021/acs.macromol.4c03081. eCollection 2025 Apr 8.
The elastic modulus is a critical parameter for the design of conjugated polymers for wearable electronics and correlates with electrical and thermal transport. Yet, widely different values have been reported for the same material because of the influence of processing and measurement conditions, including the temperature, mode, direction, and time scale of deformation. Thus, results obtained via different methods are usually not considered to be comparable. Here, disparate techniques from nanoindentation to tensile testing of free-standing films or films on water, buckling analysis, dynamic mechanical thermal analysis, oscillatory shear rheometry, and atomic force microscopy are compared. Strikingly, elastic modulus values obtained for the same batch of regioregular poly(3-hexylthiophene) differ by a factor of less than four, which suggests that an approximate comparison is possible. Considering the small amount of material that is typically available, nanoindentation in combination with creep analysis is identified as a reliable method for probing the elastic modulus of films with widely different elastic moduli ranging from less than 0.1 GPa in the case of a polythiophene with oligoether side chains to several GPa for polymers without side chains. Since films can display anisotropic elastic modulus values, it is proposed that nanoindentation is complemented with an in-plane technique such as tensile testing to ensure a full characterization using different modes of deformation.
弹性模量是用于可穿戴电子产品的共轭聚合物设计的关键参数，并且与电传输和热传输相关。然而，由于加工和测量条件的影响，包括变形的温度、模式、方向和时间尺度，对于相同的材料报道了广泛不同的值。因此，通过不同方法获得的结果通常不被认为具有可比性。在此，对从纳米压痕到独立薄膜或水上薄膜的拉伸测试、屈曲分析、动态机械热分析、振荡剪切流变学和原子力显微镜等不同技术进行了比较。令人惊讶的是，同一批区域规整的聚（3-己基噻吩）获得的弹性模量值相差不到四倍，这表明进行近似比较是可能的。考虑到通常可用的材料量很少，纳米压痕结合蠕变分析被确定为一种可靠的方法，用于探测具有广泛不同弹性模量的薄膜的弹性模量，弹性模量范围从具有低聚醚侧链的聚噻吩的小于0.1 GPa到无侧链聚合物的几GPa。由于薄膜可能显示各向异性的弹性模量值，因此建议用平面内技术（如拉伸测试）补充纳米压痕，以确保使用不同变形模式进行全面表征。
