Vinyl-Substituted Silphenylene Siloxane Copolymers:  Novel High-Temperature Elastomers

• Published in: Macromolecules Vol. 32; no. 10; pp. 3426 - 3431
• Main Authors: Lauter, Ulrich, Kantor, Simon W, Schmidt-Rohr, Klaus, MacKnight, William J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 18.05.1999
• Subjects: Applied sciences; Exact sciences and technology; Inorganic and organomineral polymers; Physicochemistry of polymers; Preparation; Solution polycondensation; Dynamic mechanical properties; Preparation; Phenylene copolymer; Experimental study; Organic silazane; Siloxane copolymer; Silicone elastomer; Thermal stability; Thermosetting resin
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma981292f

The synthesis of a series of vinyl-substituted silphenylene siloxane polymers of high molecular weight is described. 29Si NMR spectroscopy indicates that the polymers possess an exactly alternating microstructure of the silphenylene and siloxane moieties. The materials are completely amorphous with glass transition temperatures between −60 and −86 °C. All polymers degrade thermally only above 500 °C under both oxidative or inert atmosphere. The char yields at 900 °C increase with increasing vinyl content from 30% up to almost 70%. Cross-linking of a small fraction of vinyl groups by hydrosilylation gives materials with elastomeric properties. Dynamic mechanical experiments indicate that the bulk of vinyl groups cross-links thermally at temperatures above 230 °C. Therefore, the temperature window for possible applications of these materials as fire-safe elastomers extends from about −86 °C to approximately 230 °C.