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 (k(θ)) on the glass transition temperature (T(g)) of pure polymer systems, as well as polymer nanocomposites (PNCs), is investigated using molecular dynamics simulations. At small k(θ) values, the pure polymer system and respective PNCs are in an amorphous state, whereas at large k(θ) values, both systems are in a semicrystalline state with a glass transition at low temperature. For the pure polymer system, T(g) initially increases with k(θ) and does not change obviously at large k(θ). However, the T(g) of PNCs shows interesting behaviors with the increasing volume fraction of nanoparticles (f(NP)) at different k(θ) values. T(g) tends to increase with f(NP) at small k(θ), whereas it becomes suppressed at large k(θ).