Growth of Polymer Nanorods with Different Core-Shell Dynamics via Capillary Force in Nanopores

The dynamics of poly(n-butyl methacrylate) confined in porous anodic aluminum oxide (AAO) templates are investigated using differential scanning calorimetry (DSC) and fluorescence nonradiative energy transfer (NRET). Two glass transition temperatures (T-g,T-low and T-g,T-high) are obtained at higher infiltration temperatures via capillary force followed by slow cooling. Tg,low resembles the T-g of the bulk phase and represents the transition of the core layer. T-g,T-high represents the transition of the adsorbed layer in the confined polymer glass. The temperature threshold to form one or two glass transitions is determined by adjusting the infiltration temperatures and the pore diameters. It is shown that the adsorbed layer has increased interchain proximity relative to the bulk. In addition, the glass transition behavior is hypothesized to be mediated by the counterbalance of the size and interfacial effects in the confined space. The easily synthesized coreshell nanofibers with one glassy and one rubbery component without the need for block polymers have promising potential for use in several processing strategies.