Direct Ink Writing of High Performance Architectured Polyimides with Low Dimensional Shrinkage

Abstract

Despite of the outstanding chemical‐resistance, thermal and thermomechanical properties, and dielectric performance of three dimensional (3D) printed polyimides, the high dimensional shrinkage (more than 45%) between the as‐printed and final imidized objects may become the biggest obstacle on its practical applications. In this work, the authors present a two‐state curing strategy for realizing 3D printing of high performance polyimides via UV‐assisted direct ink writing (DIW) of poly (amide acid) (PAA) followed by thermal imidization. More specifically, PAA precursors modified with hydroxyethyl methacrylate are printed and thermally imidized at an elevated temperature to form 3D objects, which demonstrate a dimensional shrinkage less than 6%. The outstanding performances regarding thermal resistance, solvent‐proofing, and mechanical strength are comprehensively characterized, and some attracting polyimide functional 3D devices, such as polyimide spring and enameled wire, are readily achieved. Their DIW strategy realizes three‐dimensional polyimide architectures with low volume shrinkage and provides a tremendous potential for 3D printing of polyimides in many fields including aerospace, automobile, microelectronics, and engineering.

Additive-Manufactured Stochastic Polyimide Foams for Low Relative Permittivity, Lightweight Electronic Architectures

“…Upon the completion of phase inversion under either ambient or bath conditions, DIW polyimide structures printed with the γ C (i.e., with the highest PEG-400 content) ink consistently exhibited a linear shrinkage value <10% (∼6.0, 7.2−9.0, and 5.0−4.5% shrinkage for prism diameter, side, and height, respectively), presenting an advantage to better preserve dimensional fidelity for additive manufacturing when compared to the dimensional shrinkage values reported by post-printing imidized 3D polyimide or partial polyimide structures (Figure 3f). 21,23,24,37 Upon removal of PEG-400 content after printing, printed polyimide materials from all inks exhibited consistent glass transition temperature (Figure S3) and degradation temperature (Figure S4) of ∼315 °C and ∼500 °C, respectively. According to dynamic mechanical analysis (DMA), storage moduli of the printed filaments marginally decreased with increasing porosities (Figure S5a), and the storage moduli values of all printed polyimide materials were well maintained before reaching the glass transition temperature range.…”

High‐Resolution 3D Printing for Electronics

“…Guo et al produced PI ink that can minimize the dimensional shrinkage of the structure that occurs after thermal imidization. [77] They conducted UV-assisted direct writing using UV-curable hydroxyethyl methacrylate (HEMA) grafted polyamic acid (PAA) as printable ink. The printed ink was thermally imidized to form the PI structure.…”

Functional Dyes in Polymeric 3D Printing: Applications and Perspectives

“…DIW is widely used in printing biological materials, using various materials, such as polymers, ceramics, and composites are suitable for DIW. − Nevertheless, each material requires peculiar extrusion speed to obtain a homogenous and well-defined final product. ,− Being an extrusion-based technique, the use of dyes is not strictly necessary in DIW, since they do not affect the printing process. However, recent examples reports on the use of chromophores in photoluminescent, pH, or thermoresponsive DIW printed materials containing various organic dyes.…”