Preparation and application of aramid nanofiber via carbodiimide assisted polymerization

• The carbodiimide-assisted polymerization is used to synthesize poly(p-phenylene terephthalamide), which is a simple, mild, safe and stable method. • The condensation reagent N,N’-diisopropylcarbodiimide involved in the carbodiimide-assisted polymerization methods is highly efficient and stably recyclable. • Aramid nanofiber materials prepared from self-made poly (p-phenylene terephthalamide) all exhibited favorable mechanical and thermal properties. Poly (p-phenylene terephthalamide) (PPTA), is well known as a material with excellent properties, but its application is greatly limited due to the harsh methods required for its preparation. This study proposes an innovative carbodiimide-assisted polymerization (CAP) method to simplify the synthesis process of PPTA. The η inh of the prepared PPTA is 4.97 dl/g. Achieving amidation condensation at normal temperature and pressure, this method is suitable for synthesizing PPTA and allows for the recycling of the condensation reagent, offering a novel approach to green synthesis. Compared to the commercial fiber Kevlar 29, PPTA exhibits similar thermal stability, with negligible decomposition before 500°C. Using the deprotonation method to prepare aramid nanofiber (ANF) resulted in various shapes of bulk materials. The ANF bulk exhibits excellent mechanical properties, with tensile and compressive strengths of 36.9 MPa and 60.68 MPa, respectively, on par with standard engineering materials. Additionally, ANF and PPTA share similar thermal stability. Furthermore, the study prepared aramid nanofiber/partially hydrolyzed polyacrylamide (ANF/HPAM) composite paper, which demonstrated outstanding mechanical performance and thermal stability. The ANF/HPAM composite paper (2% concentration of HPAM) exhibited a tensile strength of 63.32 MPa. These findings offer new insights into developing high-performance fiber materials.