具有不同侧链长度的聚对苯乙炔类衍生物的杨氏模量  

Young’s Modulus of Poly-phenylene Vinylene Derivatives with Different Side-chain Lengths

作　　者：吴鲁超 田益明[1] 闫伟青 钟高余[1] WU Luchao;TIAN Yiming;YAN Weiqing;ZHONG Gaoyu(Department of Materials science,Fudan University,Shanghai 200433,China)

机构地区：[1]复旦大学材料科学系,上海200433

出　　处：《复旦学报（自然科学版）》2022年第4期444-451,共8页Journal of Fudan University：Natural Science

摘　　要：共轭聚合物在柔性电子器件中具有广泛的应用前景,但对其机械性能方面的研究比较欠缺,尤其是有机共轭聚合物侧链长度及其疏松程度对柔性器件机械性能的影响。本文利用纳米压痕仪平压头测试得到4种聚对苯乙炔(PPV)类衍生物薄膜的载荷曲线,并使用伦纳德琼斯势对卸载曲线进行拟合,获得4种PPV类衍生物薄膜的杨氏模量随外加压力的变化曲线。通过对比分析不同衍生物的杨氏模量变化曲线发现:杨氏模量与侧链长度的关系相反,即拥有较长侧链PPV的杨氏模量较小,且随外加压力的变化速度也较小,同时较长侧链的材料在压力卸载后回弹到平衡状态(F=0)时所需的时间更长。因此,根据柔性电子器件的应用场景不同,可以选择具有适当长度的柔性非共轭侧链的共轭聚合物作为敏感材料,在满足机械性能要求的同时最大限度地提高灵敏度。此外,本文也通过引入材料分子式中侧链部分占总分子量的比例(S_(w)),推导出可以根据分子结构估算杨氏模量的经验公式,为研究聚合物材料分子结构和机械性能的关系提供了一种简要的分析方法。Conjugate polymer films,due to their favorable conductivity,have good prospects in flexible electronic devices,but the mechanical properties of the polymers need to be investigated deeply,especially to the effect of side-chain length and porosity of organic conjugated polymers on mechanical properties.In this study,we obtained the loading curves of four Poly-phenylene Vinylene(PPV)derivative films by using the nano-indentation with a flat indenter and used the Leonard-Jones potential to fit the unloading curves to obtain Young's moduli of the four PPV films under different stresses.Through comparison,it is shown that Young's modulus is opposite with the side chain length,i.e.,Young's modulus of polymer with the longer side chain is smaller and its changes less with the applied stress than that with shorter side chains.Meanwhile,the polymer with longer side chains takes a longer time to restore the equilibrium state(F=0)in the unloading process.Therefore,conjugated polymers with flexible appropriate non-conjugated side chain length can be taken as sensitive materials to maximize the sensitivity while meeting the mechanical performance according to different application scenarios of flexible electronic devices.In addition,the empirical formula is obtained to calculate Young's modulus at various stresses from the molecular structure of PPV by introducing a parameter(S_(w))representing the ratio of side-chain molecular weight to the overall chain molecular weight,which is a brief analysis method for studying the relationship between molecular structure and mechanical properties.

关 键 词：侧链长度 杨氏模量 纳米压痕 伦纳德琼斯势 

分 类 号：TQ317.3[化学工程—高聚物工业]