Facile Method for the Synthesis of PCL-b-PA6-b-PCL Using Amino-Terminated PA6 as a Macroinitiator and Its Characterization

Abstract

Polyesteramides have attracted much attention due to their intriguing properties. However, the synthesis of di- or triblock polyesteramides based on polyamide 6 (PA6) remains challenging owing to their harsh reaction conditions. In this work, we introduced a new strategy to synthesize poly(ε-caprolactone)-block-PA6-block-poly(ε-caprolactone) (PCL-b-PA6-b-PCL) in a mild way. A series of well-designed copolymers were characterized by gel permeation chromatography, 1H, DOSY, and 13C NMR, and their crystallization and melting behavior, degradation rate, and compatibilization effect on PA6/PCL blends were found to be strongly composition dependent. Interestingly, the copolymers exhibited diverse spherulite morphologies, including curving stems and banded spherulites, which also correlated with the different relative content of PA6. Besides, PA6 nanodomains could act as physical cross-linking points to improve the tensile strength and Young’s modulus of PCL. This work fills the synthesis gap of well-defined PA6-based triblock polyesteramides, providing new materials for material modification and elucidation of some basic scientific questions.

Rare Lamellar Assembly Mechanism on Special Spherulites of Poly(ε-caprolactone)-b-polyamide 6-b-Poly(ε-caprolactone)

“…PCL-b-PA6-b-PCL was synthesized through melt polymerization and solution ringopening polymerization, as reported previously. 22 The triblock copolymers were denoted as PA6-PCL-1:x, where 1:x represents the molar ratio of the two repeating units according to the 1 H NMR results. The morphological study in this work mainly focuses on PA6-PCL-1:6.2.…”

“…Recently, we have successfully synthesized a series of poly(εcaprolactone)-b-polyamide 6-b-poly(ε-caprolactone) (PCL-b-PA6-b-PCL) with tunable compositions and investigated the relationship between the composition and properties in detail. 22 Interestingly, novel spherulites with a ring-banded core and curved stalks were found for some copolymers with certain composition. Therefore, based on the triblock copolymer, the effects of different heat treatments on spherulitic morphologies were studied in this work.…”

Regulation of ester contents enabled tunable thermal and mechanical properties of poly(ester amide)

“…Moreover, Gan and co-workers presented a facile method for a block copolymer (poly(ε-caprolactone)-b-(polyamide 6)-b-poly(ε-caprolactone)) and the lamellar assembly mechanism on special spherulites of copolymer was studied. 39,40 Subsequently, research on catalysts, initiators and polymerization methods was conducted. Toncheva and Mateva 41,42 synthesized poly(ε-caprolactone-co-ε-caprolactam) via anionic polymerization with CLA-Na as an initiator.…”

“…N ‐acyl lactam structure acted as a growing center for homopolymerization of CLA, while CLO acted not only as monomer but also as activator. Moreover, Gan and co‐workers presented a facile method for a block copolymer (poly( ε ‐caprolactone)‐ b ‐(polyamide 6)‐ b ‐poly( ε ‐caprolactone)) and the lamellar assembly mechanism on special spherulites of copolymer was studied 39,40 …”