High-performance polymers adapted to facile melt processing through structure design of benzocyclobutene-containing precursors

Abstract

High-performance polymeric materials with good processability and enhanced performance (higher thermal stability and mechanical strength, higher glass transition temperature (Tg) and lowered thermal expansion) have long been explored by scientists and engineers. The present study demonstrated a new way to fabricate high-performance polymers, such as polyarylamide (traditional polyarylamides can’t be processed by melt processing due to the lack of viscous flow temperature before thermal decomposition), with excellent processability via a facile two-step process, i.e. low-temperature melt processing and a subsequent in-situ thermal curing. Through designing the structure of the BCB-containing precursors, we can well control the melting point and curing temperature, thus adjust the melt processing temperature and curing temperature of the polymers. In our experiments, the temperature difference between precursor melting point and polymerization temperature can be over 200 °C, providing wide processing window and long storage lifetime. Besides, these precursors also possess excellent solubility in organic solvents, which endow them with the possibility of solution or melt processing, as illustrated by the representative precursor, DODA-BCB. The obtained polymer resin films show good thermal stability (Td,5% > 410 °C), high glass transition temperatures (Tg > 240 °C) and good mechanical strength (storage modulus > 1.8 GPa). Further studies on the thermal expansion behavior of the films reveal the thermal contracting feature of p-3,4′-ODA-BCB, the mechanism has been discussed in detail using DFT calculations, VT-FTIR and TMA.