Design of photosensitive polyimides with improved solubility, thermal stability and mechanical strength

The preparation of soluble photosensitive polyimides maintaining high mechanical properties is a challenge. By synthesizing cross-linked interpenetrating polymer networks (IPNs) composed of polyacrylate and polyimide, soluble photosensitive polyimides with high mechanical properties were successfully developed. Isophorone diamine (IPDA) was introduced as a bulky group into the polymer backbone, significantly improving the solubility of PAE. PAE demonstrated a solubility of 55 wt% in N,N-dimethylformamide (DMF). Following photopolymerization, PAE was subjected to thermal treatment, leading to the formation of IPNs composed of polyimide and polyacrylate. This process enhanced the mechanical properties, yielding a tensile strength of 122.73 MPa, a breaking elongation of 4.76%, a Young’s modulus of 5.5 GPa, and a hardness of 0.51 GPa.