Chem. J. Chinese Universities ›› 2020, Vol. 41 ›› Issue (4): 795.doi: 10.7503/cjcu20190563

• Polymer Chemistry • Previous Articles     Next Articles

Thermal Expansion Behavior of Amide-containing Polyimide Films with Ultralow Thermal Expansion Coefficient

BAI Lan1,2,ZHAI Lei1,*(),WANG Changou1,2,HE Minhui1,MO Song1,FAN Lin1,2,*()   

  1. 1. Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2019-10-31 Online:2020-04-10 Published:2020-02-17
  • Contact: Lei ZHAI,Lin FAN E-mail:zhailei@iccas.ac.cn;fanlin@iccas.ac.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(51803221)

Abstract:

A series of amide-containing polyimide i. e. poly(amide-imide) films was prepared from biphenyl tetracarboxylic dianhydride and three diamines comprising diamide groups via two-step thermal imidization method. The effect of amide structure and different substituents on mechanical properties, water absorption, thermal properties and thermal expansion behavior of poly(amide-imide) films were investigated. The results showed that these films exhibited ultrahigh tensile strength up to 280.5 MPa and excellen theat resistance with Tg above 389 ℃. Moreover, these films showed ultralow thermal expansion coefficient(CTE) from -3.05 to -1.74 ppm/℃ in the wide temperature range of 30—300 ℃. The correlation of their thermal expansion behavior with aggregation structures including molecular chain interactions, orientation and packing was systematically studied. It was found that the molecular chains of poly(amide-imide)s were highly oriented along the in-plane direction while densely packed in the out-of-plane direction, because of the hydrogen bonding interactions between amide structures and the rigid linear backbone. That was the main reason for the thermal contraction of films and contributed to their outstanding dimensional stabilities. The aggregation structures of poly(amide-imide)s could be further affected by the substituents in the backbones with different volume and steric effect, resulting in the regulation of CTE values close to zero. It provids a new design thought for the heat-resistant polymer substrates with ultralow CTE for optoelectronic application.

Key words: Polyimide, Hydrogen bonding interaction, Aggregation structure, Thermal expansion behavior

CLC Number: 

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