Exploring The Impact of Blend And Graft of Quinoline Derivative in Low-temperature Curable Polyimides.

The utilization of accelerators has been a common approach to prepare low-temperature curable polyimide (PI). However, the accelerators have gradually fallen out of favor because of their excessive dosages and negative effect on the properties of PI. In this work, a new strategy of introducing accelerators by grafting to eliminate these disadvantages is presented. A novel quinoline derivative named NQL was designed for this purpose, and an ultra-low dosage of only 2.5 mol% was sufficient to prepare low-temperature curable PI. The favorable low-temperature curing effect of NQL was attributed to its strong alkalinity (pKa = 18.47) and electron-donating ability (HOMO = -6.22 eV). At a curing temperature of 200 °C, the PI with 2.5 mol% NQL showed outstanding properties (Young's modulus of 5.73 GPa, elongation of 37.3%, tensile strength of 237 MPa and coefficient of thermal expansion of 16 ppm/K). In particular, NQL could even lower the curing temperature to 180 °C and the ultra-low temperature curable PI film still retained excellent properties. These results demonstrate that introducing low-temperature curable accelerators by partial grafting instead of blending is a promising way to furnish low-temperature curable PI, and provide insights into the preparation of polyimide with high performance in advanced packaging. This article is protected by copyright. All rights reserved.