Synthesis of Laboratory Nylon: A Scale-Up Method for High Molecular Weight Polyamides

Abstract

Here, we report a benchtop scale two-stage polyamidation process for the synthesis of diacid/diamine (AA-BB) type polyamides (PAs) in quantities sufficient (30 g+) to obtain ASTM dogbones, IZOD bars, and rheology specimens with molecular weights ranging from 15 to 35 kDa and minimal to no discoloration. Despite the extensive body of research in recent years reporting biobased AA-BB type PAs, the scale and molecular weights reported by many researchers are often inadequate for meaningful comparisons with industrial resins. Commercially produced PAs usually use an initially high-pressure, moderate-temperature oligomerization reaction to prevent the diacid’s decarboxylation and the diamine’s evaporation. Subsequently, a second stage employs a higher temperature at reduced pressure and inert sweep gas for molecular weight enrichment without significant oxidative degradation. We have sourced commercial hardware and made simple modifications, such as a robust agitator capable of wall-sweeping, to ensure uniform heat and mass transfer. The resulting PAs exhibit mechanical properties on par with industrially sourced controls, demonstrating the effectiveness of our approach in bridging the gap between academic and industrial PAs. This eliminates one of the significant roadblocks associated with developing new industrially relevant polyamides and should be broadly applicable to researchers struggling with the challenges of polyamidation.