𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Thermal stability of polydimethylsiloxane. II. Formation of stable complexes on basic active centers

✍ Scribed by Kučera, M. ;Láníková, J.

Book ID
104532199
Publisher
John Wiley and Sons
Year
1962
Weight
350 KB
Volume
59
Category
Article
ISSN
0022-3832

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Amphoteric hydroxides are found to possess a great ability to deactivate the “living” ends of polydimethylsiloxane molecules. They not only prevent depolymerization but also suppress the formation of crosslinks between polymer molecules (which is due to the oxidation of methyl groups). Deactivation of active centers can also be carried out by benzoic acid; however, this acid attacks siloxane bonds at elecated temperatures and promotes decreased molecular weight of polydimethylsiloxane. This undesirable decrease in molecular weight is not caused by benzoic acid only in polymers which originally contained basic active centers; it is found also in polymers without any “living” ends, whether these were removed by transformation into stable complexes or decomposed by heating at 150°C. (as in the case of SiOPBu~4~).

📜 SIMILAR VOLUMES

Changes in the rate of anionic polymeriz
Changes in the rate of anionic polymerization of octamethylcyclotetrasiloxane caused by the formation of complexes on silanolate active centers
✍ Kučera, Miloslav 📂 Article 📅 1962 🏛 John Wiley and Sons ⚖ 786 KB

## Abstract The effect of bases on the anionic polymerization of octamethylcyclotetrasiloxane (tetramer) initiated by ∼Si—OK groups has been studied. In the presence of hydroxides of alkali metals or of other Lewis bases, in particular of anisole, complexes are formed on active centers which alter