Polymer Synthesis: Theory and Practice by Dietrich Braun Harald Cherdron Matthias Rehahn Helmut Ritter & Brigitte Voit

Author:Dietrich Braun, Harald Cherdron, Matthias Rehahn, Helmut Ritter & Brigitte Voit
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

3.2.3.2 Ring-Opening Polymerization of Cyclic Acetals

Like THF, cyclic acetals (e.g., 1,3-dioxolane and 1,3,5-trioxane) are polymerizable only with cationic initiators. The ring-opening polymerization of 1,3,5-trioxane (cyclic trimer of formaldehyde) leads to polyoxymethylenes (see Example 3.24), which have the same chain structure as polyformaldehyde (see Example 3.22). They are thermally unstable unless the semiacetal hydroxy end groups have been protected in a suitable way (see Example 5.7). Like the cyclic ethers, the polymerization of 1,3,5-trioxane proceeds via the addition of an initiator cation to a ring oxygen atom, with the formation of an oxonium ion which is transformed to a carbenium ion by ring opening. The chain propagates by the addition of further 1,3,5-trioxane molecules:

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