Cationic ring-opening epichlorohydrin

The cationic ring-opening polymerization of epichlorohydrin in conjunction with a glycol or water as a modifier produced hydroxyl-terminated epichlorohydrin (HTE) liquid polymers (1-2). Hydroxyl-terminated polyethers of other alkylene oxides (3 4), oxetane and its derivatives (5 6), and copolymers of tetrahydrofuran (7-15) have also been reported. These hydroxyl-terminated polyethers are theoretically difunctional and used as reactive prepolymers. 

HTE liquid polymers were synthesized by cationic ring-opening polymerization of epichlorohydrin (ECH) in the presence of water or ethylene glycol (EG) as a modifier (1). Cyclic oligomers were removed by extraction. After extraction, the liquid polymers were essentially free from cyclic oligomers as determined by gel permeation chromatography (GPC) (Figure 1). 

Cationic Ring-Opening Polymerization of Epichlorohydrin in the Presence of Ethylene Glycol... 

Cyclic ethers are the class of heterocyclic monomers that provide suitable models for mechanistic studies. Polymerization of several monomers of this class leads to polymeric materials that are produced on an industrial scale. The most prominent examples are polymers of ethylene oxide (EO), propylene oxide (PO), epichlorohydrin (ECH), or tetra-hydrofiiran (THE). Cationic ring-opening polymerization (CROP) of cyclic ethers is thus interesting from both an academic and industrial point of view. 

Polyethers are prepared by the ring opening polymerization of three, four, five, seven, and higher member cyclic ethers. Polyalkylene oxides from ethylene or propylene oxide and from epichlorohydrin are the most common commercial materials. They seem to be the most reactive alkylene oxides and can be polymerized by cationic, anionic, and coordinated nucleophilic mechanisms. For example, ethylene oxide is polymerized by an alkaline catalyst to generate a living polymer in Figure 1.1. Upon addition of a second alkylene oxide monomer, it is possible to produce a block copolymer (Fig. 1.2). 

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