Flexible preparation of polyamide-6 based thermoplastic elastomers via amide exchange

The harsh synthesis conditions and lack of hard segments have long presented difficulties in the preparation of polyamide-based thermoplastic elastomers (TPAEs). In this work, a facile synthesis of TPAEs was developed using amide exchange. First, itaconic acid-polyoxypropylene diamine copolymer (IA-PPA) was synthesized by copolymerizing bio-based polyoxypropylene diamine (PPA D400) and itaconic acid (IA). The P2000 (IA-PPA with Mn ~ 2000) was then used as the soft segment of polyamide-6 based thermoplastic elastomers (PA6-b-P2000). Experimental results indicate that P2000 could directly initiate the ring-opening polymerization of caprolactam to form a prepolymer containing PA6 segments. PA6-b-P2000 thermoplastic elastomers were then obtained by the amide exchange reaction of PA6 segments. The structure and properties of IA-PPA and PA6-b-P2000 were further characterized in detail. The results demonstrate that the elastomers have good thermal stability and superior elasticity, which are highly dependent on the crystallinity and phase separation structure of the polyamide elastomer. Using this flexible approach, multifunction TPAEs can be designed and commercialized in a short time.