Determining Young's modulus of MEH-PPV film by fitting the unloading curve

作者：Zhong, Gao-yu^*; Yan, Wei-Qing; Li, Jie; Tian, Yi-ming

来源：Microsystem Technologies, 2019, 25(4): 1467-1474.

DOI：10.1007/s00542-018-4185-7

• MECHANICAL-PROPERTIES
• ELASTIC-MODULUS
• POLYMER
• NANOINDENTATION
• STRESS

The loading-unloading curves of poly(methoxy-5-(2'-ethylhexyloxy)-1,4-phyen-ylenevinylene) (MEH-PPV) films were measured using four different tests of nanoindentation. Then the curves were simulated with the theory of Lennard-Jones (L-J) potential, discovering the relationship between Young's modulus (modulus, E) and the indented depth or force. Therefore, it is proposed that the modulus of a soft conjugated polymer can be calculated by fitting the unloading curve. This method of modulus determining is different from that the well-accepted and widely used, which traditionally comes from the stiffness at the beginning of the unloading curve. The modulus of the MEH-PPV film, which usually varies with stress or strain, is calculated to be 70 MPa on the equilibrium position where the intermolecular potential is minimal and the intermolecular force is zero. This method will be beneficial for the standardization of modulus measuring of soft polymer thin films.

• 出版日期2019-4
• 单位复旦大学