Super-heat resistant, transparent and low dielectric polyimides based on spirocyclic bisbenzoxazole diamines with <i>T</i>_g &gt; 450 °C

Abstract

A series of isomers with a spiro-ring structure connecting two benzoxazole rings were synthesized, and their corresponding polyimides showed high heat resistance ( T g = 491 °C) and transparency ( T 550 nm = 90%).