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

Abstract

The cationic ring-opening polymerization of epichlorohydrin co-initiated by BF 3 •Et 2 O has been investigated here. Fast synthesis of pure poly(epichlorohydrin) diols (F n (OH) ≈ 2.0) with controlled molar mass (M n up to 4000 g mol −1 ) and low dispersity (Đ < 1.25) was performed both in toluene and in bulk. An original approach was developed here, consisting of first generating in situ the initiator through the BF 3 •Et 2 O-catalyzed reaction of ECH with water, leading to a mixture of oligomers with better solubility in the reaction medium than conventional initiators previously used. Then, through a second monomer starved-feed step, polymerization proceeds exclusively through the activated monomer mechanism, allowing perfect control of the polymer growth. The developed procedure was successfully upscaled to 100 g of polymer to validate a future industrial production of PECH, as well as its derivative glycidyl azide polymer (GAP), the most important energetic binder for solid propellants. Additionally, a separate study was performed to elucidate the reasons for coloration of the polymer observed in the course of polymerization and/or under storage.

Ionic liquid post-modified carboxylate-rich MOFs for efficient catalytic CO2 cycloaddition under solvent-free conditions

“…Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, exhibit easier epoxide opening due to the electron-withdrawing ability of the Cl and Br substituents as well as the steric effects of bulky halogen atoms. 66–68 Additionally, Gd-TPTC-NH-[BMIM]Br exhibits higher catalytic activity towards 2-methyloxirane compared to styrene oxide. This difference can be attributed to the increased steric hindrance posed by the benzene ring, thereby presenting a catalytic challenge for the nucleophilic bromide ion.…”