The Role of Polymer Chain Stiffness and Guest Nanoparticle Loading in Improving the Glass Transition Temperature of Polymer Nanocomposites

The impact of polymer chain stiffness characterized by the bending modulus (kθ) on the glass transition temperature (Tg) of pure polymer systems, as well as polymer nanocomposites (PNCs), is investigated using molecular dynamics simulations. At small kθ values, the pure polymer system and respective PNCs are in an amorphous state, whereas at large kθ values, both systems are in a semicrystalline state with a glass transition at low temperature. For the pure polymer system, Tg initially increases with kθ and does not change obviously at large kθ. However, the Tg of PNCs shows interesting behaviors with the increasing volume fraction of nanoparticles (fNP) at different kθ values. Tg tends to increase with fNP at small kθ, whereas it becomes suppressed at large kθ.