Über den einfluß von reglern auf die polymerisation des trioxans

Abstract

ZUSAMMENFASSUNG:Die Untersuchung der Regelung der Trioxanpolymerisation durch verschiedene Ketteniibertrager fiihrte zu dem Ergebnis, dal3 wahrend der Polymerisation als Nebenreaktion eine Hydridwanderung stattfindet. Analytische Untersuchungen erharteten diesen Befund. Die intramolekulare Hydridwanderung liefert Methylkationen, die ihrerseits die Polymerisation oder eine Transacetalisierung auslosen. Hydridwanderung und Transacetylisierung sind fiir die kationische Polymerisation von Trioxan und Formaldehyd charakteristisch.Weitere Untersuchungeu fiihrten zur Auffindung neuer Regler, wie Borsaureester und alkylsubstituierte Aromaten. Ferner gelang es, Polyoxymethylene mit ungesattigten, Nitrilund Peroxy-Endgruppen herzustellen. SUMMARY :Chain transfer of cationic trioxane polymerisation with several transfer agents was inv-estigated, showing that during polymerisation a hydride shift takes place as side-reaction. This was confirmed by analytical investigations. The intramolecular hydride shift yields methyl cations which on their part release polymerisation or transacetalisation. Hydride shift and transacetalisation are characteristic for the cationic polymerisation of trioxane and formaldehyde.Several new chain transfer agents such as esters of boric acid and alkyl substituted aromatic compounds were found. Furthermore polyoxymethylenes with unsaturated, nitrile, and peroxy end groups were prepared.

ABA Triblock Copolymers Based on Linear Poly(oxymethylene) and Hyperbranched Poly(glycerol): Combining Polyacetals and Polyethers

“…However, POM-based block copolymers might be an interesting alternative to the random copolymerization approach to improve processing and to modify the property profile of POM. Some attempts to tailor the properties of POM by introducing functional groups mainly relied on three strategies: (i) conversion of the two hydroxyl end groups with suitable reagents, , (ii) integration of functional groups into the polymer backbone by transfer reactions during the polymerization, ,,, or (iii) copolymerization of trioxane with functional comonomers …”

“…However, POM-based block copolymers might be an interesting alternative to the random copolymerization approach to improve processing and to modify the property profile of POM. Some attempts to tailor the properties of POM by introducing functional groups mainly relied on three strategies: (i) conversion of the two hydroxyl end groups with suitable reagents, 12,13 (ii) integration of functional groups into the polymer backbone by transfer reactions during the polymerization, 12,14,15,9 or (iii) copolymerization of trioxane with functional comonomers. 16 In contrast, hyperbranched poly(glycerol) (hbPG), obtained by cationic 17,18 or anionic 19,20 ring-opening multibranching polymerization (ROMBP) of glycidol, offers tremendous possibilities for further functionalization due to its polyol structure.…”