Two new polyphosphazenes, poly(4-maleimidophenoxy/phenoxy)phosphazene and poly(4-phthalimidophenoxy/phenoxy)phosphazene, were prepared and used to toughen a PMR polyimide designated LaRCTMRP46. These toughened polyimides were evaluated as thin films with a 0–40 wt% range of polyphosphazene to polyimide. The structure–property relationships of these inorganic/organic polymeric matrices were studied and evaluated in terms of fracture toughness, thermo-oxidative stability, and thermal, mechanical, and tensile properties. The hybrid systems revealed an increase in fracture toughness up to 20 wt% polyphosphazene load without any substantial loss in tensile properties. With 5 wt% poly(4-phthalimidophenoxy/phenoxy)phosphazene loading, the fracture toughness of the semi-interpenetrating network was increased by 124%. When 10 wt% poly(4- maleimidophenoxy/phenoxy)phosphazene loading was used, the fracture toughness of the grafted copolymer was improved by 217%. In addition, substantial enhancement in thermo-oxidative stability was also observed.
Temperature-dependent dynamic moduli of Parylene-C columnar microfibrous thin films