Tuning Physicochemical Properties of Polymers through Extreme Nanoconfinement*

Extreme nanoconfinement of a polymer can be achieved by infiltrating a polymer into a highly-loaded nanoparticle (NP) film via Capillary Rise Infiltration (CaRI). Here, we explore the properties of polymers in CaRI films with various strengths of interfacial interactions. Polyethersulfone (PES), poly (2-vinylpyridine) (P2VP), or polystyrene (PS) are infiltrated into SiO₂ NPs. Physicochemical properties of these polymers are tuned under various confinement conditions using NPs with various sizes (3−30 nm average pore sizes) and various degrees of NP sintering prior to infiltration. Extreme enhancement of the glass transition temperature (T_g) is observed with T_g increases as high as 106K above bulk T_g for the 11nm sintered NP packings infiltrated by PES. In this case both entropic and enthalpic effects contribute to T_g enhancement. Nanoconfinement leads to substantial improvement in thermal stability of polymers. Upon heating at elevated temperatures, polymers with less char residues are more resistant to degradation.