Reactive oligomers and polymers: Synthesis and application for polymer modification

The classification of reactive oligomers and some aspects of their reactivity in crosslinking systems is discussed, and related to three experimental attemps to contribute to a better understanding of epoxy network modification by reactive oligomers and polymers. The synthesis and modification of telechelic oligomers with functional groups at the chain end as starting materials for modified epoxies proved to be successful only when all the mechanisms occurring below gel point had been investigated by model reactions on the one hand and, on the other, when the actual determination of their influence on the network structure had been established. Ethylene‐vinylalcohol copolymers with a controllable amount of hydroxylic groups are a convenient model system. The reaction of OH‐groups with acid anhydrides produces carboxylic groups attached onto the polymer chain which are useful as hardeners for epoxy resins. The mechanisms of the synthesis and of the crosslinking reactions are more complex than might be expected. More information is now available about the amount of oligoether sequences in epoxies prepared by anionically and cationically induced crosslinking of glycidyl ethers. Using model compounds, several different types of oligomers have been found which depend on the initiating agent.