Reactions of Zirconium (IV) n‐Propoxide with SiH‐Functional Polysiloxanes as a Route to Siloxane–Zirconium Hybrid Materials with Enhanced Refractive Index. Issue 5 (3rd December 2020)

• Record Type: Journal Article
• Authors: Rubinsztajn, Slawomir; Chojnowski, Julian; Mizerska, Urszula; Basko, Malgorzata; Uznanski, Pawel; Walkiewicz‐Pietrzykowska, Agnieszka; Cypryk, Marek
• Other Names: Brook Michael A. guestEditor.; Skov Anne L. guestEditor.
• Is Part Of: Macromolecular rapid communications. Volume 42:Issue 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-03
• Subjects: high refractive index -- hydride‐functional siloxanes -- hydrolysis and condensation -- siloxane–zirconium nanocomposites -- zirconium alkoxides; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202000601
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: The reaction of poly(hydromethylsiloxane‐ co ‐methylphenylsiloxane) with zirconium (IV) n ‐propoxide in dry toluene leads to extensive scission of the siloxane chain and conversion of Si‐H groups. These processes produce oligomeric siloxanes and organosilanes containing moisture sensitive propoxy and siloxy‐zirconate groups. The obtained post‐reaction solution of zirconium containing heterosiloxane oligomers is stable under anhydrous conditions for several weeks. However, its exposure to moisture initiates the hydrolytic condensation of the reactive groups leading to cross‐linking and the formation of a siloxane–zirconium composite. Spin coating of the siloxane–zirconium prepolymer followed by exposure to moisture produces thin films with excellent light transparency and increased refractive index. The final coatings are characterized by ellipsometry, UV–Vis, IR, and 29 Si MAS NMR spectroscopies. Abstract : Propoxy‐ and siloxy‐zirconate functional siloxane oligomers mixture is prepared by reacting poly(phenylmethylsiloxane‐ co ‐hydromethylsiloxane) with zirconium (IV) n ‐propoxide at elevated temperature in toluene. Exposure to moisture of this highly functional siloxane–zirconium prepolymer initiates zirconium catalyzed hydrolytic condensation reactions resulting in a strongly cross‐linked siloxane–zirconium nanocomposite with excellent light transparency above 230 nm and high refractive index.