Polyethers used in epoxy resins

Since epoxides are reactive compounds, the epoxy groups present in pre-polymers are used for crosslinking or curing purposes. Curing occurs when the pre-polymer is treated with a suitable multi-functional crosslinking agent, or with an accelerator. The 

The pre-polymers typically contain at least two epoxy groups spaced with an aromatic or aliphatic backbone or even by a fragment of chain including other functionalities. The most commonly used resin from this class is probably formed from epichlorohydrin and bisphenol A or 4-[1-(4-hydroxy-phenyl)-isopropyl]phenol under basic conditions to give a polymeric diglycidyl polyether as shown below  

1 -benzyI-2-methyl- 2-undecylimidazole imidazole (1B2MZ) (C11Z) 

The mechanism of curing of the epoxy pre-polymer using, for example, imidazole derivatives is indicated schematically by the following reactions  

Other crosslinking reagents include hexahydrophthalic anhydride, 4,4 -diaminodiphenylsulfone, 4,4 -diamlnodiphenylether, triethylenetetramine, norbornyl dianhydride siloxane, etc. 

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