Online monitoring of reaction temperature during cationic ring opening polymerization of epichlorohydrin in presence of BF₃ and 1,4‐butanediol

Abstract

This work introduces cationic ring opening polymerization of polyepichlorohydrin (PECH) produced under various reaction conditions (set temperature: −10 to 40°C, [C]/[I] ratio: 0.1–1, monomer feed rate: 1–4 mL/min). In addition, a correlation between the exothermic reaction temperature and the performance of the PECH was obtained by utilizing a reaction temperature monitoring system, GPC, 1H‐NMR, and FTIR. During the polymerization, an induction period which affects the polydispersity was observed below 10°C. At lower temperatures and lower [C]/[I] ratios, a higher induction period was observed. The monomer feed rate did not affect the induction period but it highly affected the polydispersity when the induction period occurred. The total molecular weight of PECH increased with decreasing set temperature even though the amount of low molecular weight cyclic oligomer increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39912.

Chlorinated Solvent-Free Living Cationic Ring-Opening Polymerization of Epichlorohydrin Using BF3•OEt2 as Co-Initiator: Toward Perfectly Functionalized Poly(epichlorohydrin) Diols

“…1,4-cyclohexanediol, and even polyethylene glycols ( M n = 200–600 g mol –1 ) were used as initiators of cationic ROP of ECH in conjunction with BF 3 •Et 2 O, mainly at 0 °C. However, PECH s obtained with these different initiators are often characterized by relatively high dispersity (Đ = 1.40–2.15) and a functionality lower than 2.0; moreover, their SEC traces display shoulder or even a separate peak in the low molar mass region, indicating the formation of cyclic by-products. − The main differences between these works and Penczek’s one lie in the nature of the initiator, the polymerization temperature, and the initiator to co-initiator ratio ([EG]/[BF 3 •Et 2 O] ≈ 50).…”

“…Clearly, PECH s synthesized by catalytic or anionic means are not ideal tools for the preparation of GAP, principally because of the lack of desired functionality. In stark contrast, the cationic ROP of ECH in conjunction with a molecular diol as an initiator results systematically in dihydroxy-terminated PECH. − Two different mechanisms, i.e., activated chain end (ACE) and activated monomer (AM) mechanisms, simultaneously operate during the ROP of ECH, depending on the reaction conditions (Scheme ). In the ACE mechanism, the active propagating species are oxonium ions located at the chain ends and propagation occurs through the addition of neutral monomer molecules to these oxonium ions (Scheme a).…”

“…The cationic ROP of ECH was already largely described in the literature, using catalytic systems based on Lewis acids such as BF 3 •Et 2 O, − SnCl 4 , Et 3 O + PF 6 – , and…”

“…They used an ethylene glycol (EG)/BF 3 •Et 2 O initiating system in CH 2 Cl 2 or in bulk and proceeded by slow addition of ECH (48 h) at 20 °C. Since then, many other diols such as BD, − , diethylene glycol, , 1,2-propanediol, hexylene diol,…”

“…Such an induction period was rationally attributed to the poor solubility of initiator (BD) in dichloromethane at low reaction temperature. Interestingly, the decrease of BF 3 •Et 2 O concentration (below [BD]/[BF 3 •Et 2 O] = 2) resulted in an increase of exothermicity during the polymerization, after the induction period ceased. , …”