Synthesis and Ring-Opening Polymerization of 5-Azepane-2-one Ethylene Ketal: A New Route to Functional Aliphatic Polyamides

Abstract

A functional derivative of ε-caprolactam, 5-azepane-2-one ethylene ketal or γ-ethylene ketal ε-caprolactam, has been synthesized by a very straightforward and highly efficient Beckmann rearrangement reaction. Homopolymers of this new monomer and its copolymers with ε-caprolactam have been synthesized by anionic ring-opening polymerization using N-acetyl-ε-caprolactam and NaH. The ketone groups can be easily released by deacetalyzation, and subsequent reaction leads to complete reduction to hydroxyl pendant groups. The ketone-containing (co)polymers respond sensitively to both thermal and photo-cross-linking in this novel class of materials. These new aliphatic polyamides bearing either ketone or hydroxyl pendant groups provide entries into a large number of application areas.

Controlled synthesis of crosslinked polyamide 6 using a bis-monomer derived from cyclized lysine

“…Applicability of PA6 0 s engineered plastics with enhanced physico-chemical properties can be obtained by using functional caprolactams [21e28] which are capable to homopolymerize or copolymerize with CL by anionic or hydrolytic routes. Homopolymers of 5-azepane-2-one ethylene ketal (g-ethylene ketal-ε-caprolactam) and its copolymers with ε-caprolactam have been successfully synthesized by anionic ringopening polymerization process using N-acetyl-caprolactam and NaH at 140 C [21]. The deacetylation of the poly(g-ethylene ketal-ε-caprolactam) quantitatively releases ketone group which can further be reduced yielding a poly[imino(4-hydroxyl-1-oxohexane-1,6-diyl)].…”

“…The deacetylation of the poly(g-ethylene ketal-ε-caprolactam) quantitatively releases ketone group which can further be reduced yielding a poly[imino(4-hydroxyl-1-oxohexane-1,6-diyl)]. Both, the racemic and optically active poly[imino(4-hydroxylmethylene-1-oxohexane-1,6-diyl)] was synthesized by anionic ring-opening polymerization of their corresponding tertbutoxymethylene-ε-caprolactam after the tert-butyl protective groups were removed by acidolysis in the presence of traces of HCl [21]. These PA6 bearing hydroxyl pendant group could provide new pathway for further developments.…”

“…These PA6 bearing hydroxyl pendant group could provide new pathway for further developments. Thin films of PA6 and its copolymers containing higher than 25 mol % of imino(1,4-oxohexane-1,6-diyl) monomer units sensitively responding to thermal (300 C) or UV (40 W/cm 2 mercury lamp) photo-crosslinking reactions have been reported [21]. Here the crosslinking was demonstrated by the insolubility of the resulting materials, usually solubilized in trifluoroethanol, and the higher glass transition temperatures of the materials with the increasing monomer feed ratio g-ethylene ketal-ε-caprolactam/ε-caprolactam.…”

Functional Polyamides: A Sustainable Access via Lysine Cyclization and Organocatalytic Ring-Opening Polymerization

“…It is desirable to have poly(ε-caprolactam) encoding a wide variety of functional pendants to expand its versatility and tune properties such as crystallinity, hydrophilicity, and biodegradability or to further conjugate biomacromolecules and fluorescence probes pendant to the backbone. 24,25 The very limited pendant diversity of poly(ε-caprolactam) hampered the investigation of its potential biological and medical applications: most reported examples were simple carboxyl or hydroxyl groups appended to the backbone, as shown in Scheme 1. 25−29 This limitation in functionality was related to constraints on ε-lactam derivatives synthesis and harsh polymerization conditions.…”

Preparation, characterization and copolymerization of the 12‐membered cyclic diamide 1,6‐diazacyclododecane‐2,5‐dione

“…Polyamide 6, or nylon 6, is generally prepared by ring‐opening polymerization of ε‐caprolactam (CLA). CLA is most widely polymerized via hydrolytic or anionic polymerization methods. Although it is not commercially used, cationic ring‐opening homo‐ and copolymerization is also of research interest .…”