Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

Abstract

The activated anionic ring-opening polymerization of e-caprolactam initiated by 0.35 mol% of combined initiator, i.e., equimolar mixture of magnesium di(e-caprolactamate) (CL 2 Mg) with magnesium halides (MgCl 2 , MgBr 2 , and MgI 2 ) as well as of e-caprolactam magnesium bromide (CLMgBr) in the presence of 0.35 mol% of N-acetyl-e-caprolactam as an activator has been investigated in the temperature range 140-200°C. It was found that the reaction rate increased while the apparent activation energy decreased in the following series: CL 2 Mg/ MgCl 2 \ CL 2 Mg/MgBr 2 * CLMgBr \ CL 2 Mg/MgI 2 . In addition, the poly(ecaprolactam)s prepared with CL 2 Mg/MgX 2 (MgX 2 = MgCl 2 , MgBr 2 , and MgI 2 ) are characterized by slightly higher thermal stability than polymers obtained with CLMgBr as initiator. These observations were explained in terms of the coordination of Lewis acids (MgX 2 , where X = Cl, Br, and I) with imide carbonyl of N-acyllactam end groups leading to the increase of their reactivity and stability.

Cationic polymerization of 1,3‐pentadiene coinitiated by zinc halides

“…The higher activity of ZnBr 2 as compared to ZnCl 2 was also observed in the cationic polymerization of cyclopentadiene coinitiated by zinc halides 23. This difference is consistent with the increase of Lewis acidity and/or decrease of lattice energy of corresponding metal halide (MX n, M = metal, X = Cl, Br, I) in a series: MCl n < MBr n < MI n 28. In other words, among all investigated in this work ZnX 2 ‐based initiating system homogeneous TCAA/ZnBr 2 initiating system showed the highest activity in the cationic polymerization of 1,3‐pentadiene, which is comparable with the activity of most active catalytic system based on TiCl 4.…”

Synthesis and characterization of star-branched polyamide 6 via anionic ring-opening polymerization with N , N′ , N″ -trimesoyltricaprolactam as a multifunctional activator

“…The anionic ROP of CL is an attractive protocol to melting cast polyamide 6 (MC PA6) in industry owing to the shorter reaction time (10-30 min), lower reaction temperature (150-180 8C) and pressure (atm) [14][15][16]. The anionic polymerization was usually conducted by a two-component system of a catalyst and an Nacyllactam type activator.…”

Dual catalysis with an N‐heterocyclic carbene and a Lewis acid: Thermally latent precatalyst for the polymerization of ε‐caprolactam

“…Similar effects of Lewis acids, including CLA-MgBr as initiator, have been mentioned earlier. 5,13,48…”