Functionally gradient silicone sheet made by treatment of swelling and polymerization with n ‐butyl methacrylate

A silicone sheet was dipped into n ‐butyl methacrylate monomer including benzoyl peroxide and was swollen for 0.5 h at 23°C. Then, the sheet was put into a glass tube equipped with a three‐way stopcock and was deoxygenated by freezing under dry nitrogen. Polymerization was carried out by heating at 80°C for 2 h under dry nitrogen. The resultant sheet was a component gradient silicone sheet with poly‐ n ‐butylmethacrylate. The content of poly‐ n ‐butylmethacrylate increased gradually from either surface to the middle of the sheet. This phenomenon was assumed to occur because of the volatilization of n ‐butyl methacrylate monomer during the polymerization. The properties of the sheet include increased tear strength and decreased gas permeability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3152–3155, 2002; DOI 10.1002/app.10177