A poly(organophosphazene) bearing allylic functions (POPZ (1)) has been grafted onto the surface of a poly(vinyl alcohol) (PVA) film with the aid of the benzoyl peroxide initiator. The PVA films were first coated with toluenic solutions of POPZ and peroxide and then heated . After grafting, they were extracted with toluene to remove ungrafted POPZ. The resultant surfaces were characterized by ATR-IR, UV, XPS spectroscopies, X-ray fluorescence spectrometry, and gravimetric and contact angle measurements. The presence of the covalently bonded and cross-linked POPZ on the PVA surface gives it hydrophobic character, which may be helpful in improving the oxygen-barrier properties at high humidity.
Triethoxysilane HSi(OEt) 3 was used as coupling agent to graft a poly(organophosphazene) (POPZ) containing allylic functions to the surface of poly(vinyl alcohol) or poly(ethylene-co-vinyl alcohol) films. Hydrolyzed HSi(OEt) 3 , which contained both inorganic (Si-OH) and organic (Si-H) reactivities, acted at the interface between the hydroxylated substrates (via a condensation reaction) and the allylic functions in POPZ (via a hydrosilylation reaction). Starting materials and grafting surfaces were studied by ATR-IR and XPS spectroscopies and contact angle measurements. Data obtained indicated that different POPZ layers were produced, depending on whether the functionalization of materials with silane, and the grafting reaction were separately or simultaneously made. The POPZ layer thickness was higher when the grafting reaction was preceded by the POPZ functionalization. In each cases, the modified surfaces showed marked increases in hydrophobicity character.
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