The Effect of Extreme Spatial Confinement and Interfacial Interactions on the Glass Transition of Polymers in Polymer-infiltrated Nanoparticle Packings

摘要

It has been known that chain and segmental confinement of polymer and polymer-particle interfacial interactions in polymer nanocomposites can have influence on polymer properties compared with the bulk. By Capillary Rise Infiltration (CaRI), polymer infiltrates into nanoparticle (NP) packings and gets confined within the small pores. In this study, the influence of spatial confinement and interfacial interactions on the glass transition temperature (Tg) of polymers in Si02 NP packings was investigated. The degree of confinement was controlled by changing molecular weight of the polymers as well as the size of NPs (11～100 nm), producing 3~30 nm pore diameter. Interfacial interaction was tuned by using polymers with different interaction with Si02, polystyrene (PS) and poly(2-vinylpyridine) (P2VP). We show that the major factor that significantly increases Tg of polymers in these NP packings is the small pore. Only in highly confined conditions can stronger interfacial interaction further increase Tg. For example, for 8 kg/mol polymers, in 11 nm NP packings, Tg of PS and P2VP increases by 50 K and 93 K, respectively, while Tg is close to bulk in 100 nm NP packings for both polymers.