Synthesis of High Molecular Weight Poly (1, 1, 12, 12-tetramethyl-13-oxa-1, 12-disilatridecanylene-co-dimethylsiloxane) Using Anionic Ring-opening Polymerization

Abstract

High molecular weight copolymers, referred to as polysilalkylene siloxanes or hybrid silicones, were prepared using anionic ROP of 1,1,3,3,14,14,16,16-octamethyl-2,15-dioxa-1,3,14,16-tetrasilacyclohexacosane (II) and octamethylcyclotetrasiloxane (D4) mixtures. The resultant gum-like polymers were characterized by 1 H NMR, 13 C NMR, 29 Si NMR, FTIR, GPC, TGA and FTIR. It was determined that the resultant polymers possessed a ratio of alkylene to dimethylsiloxane units similar to that expected from the original monomer ratio. Number averaged molecular weights ranged from 111,000 to 160,900 g/mol in yields of 75% to 78%. In addition, the thermal stability of the poly(decanylene-co-dimethylsiloxane)s were similar to that of the homopolymer based on II.

The Thermal Degradation Behaviour of a Series of Siloxane Copolymers - a Study by Thermal Volatilisation Analysis

“…13 C NMR analysis of the cold-ring fractions obtained from the polysilalkylenesiloxane samples, an example of which presented in Figure 8, confirms the presence of five aliphatic carbons having chemical shifts between 17 and 33 ppm. This is identical to those reported for the alkylene units within the virgin polymers [20] suggesting that some Si-alkylene-Si units can volatilise intact from the degrading copolymers despite the relatively low Si-C bond strength. Analysis of the cold-ring fractions, therefore, reveals that the polysilalkylenesiloxanes degrade to yield high molecular mass materials which are structurally different to those obtained from the commercial PDMS sample.…”

Thermal insulation and stability of polysiloxane foams containing hydroxyl-terminated polydimethylsiloxanes

“…It is usually synthesized by ring-opening polymerization of hexamethylcyclotrisiloxane or octamethylcyclotetrasiloxane (D 4 ). [24][25][26] Cross-linking is based on the polycondensation and polyaddition reaction in the presence of a catalyst. One of the processes occurs between the silanol groups and the Si-H groups of polymethylhydrosiloxane (PMHS) with the evolution of hydrogen.…”