Fragility of an Isochorically Confined Polymer Glass.
We report the effect of isochoric confinement on the dynamic fragility of a polymeric glass-former, that is, polystyrene (PS). Utilizing silica-capped PS nanospheres as a model system, the fictive temperature (Tf) and the isochoric heat capacity (Cv) are measured as a function of diameter via differential scanning calorimetry. By examining Tf as a function of cooling rate for each sample, the isochoric fragility (mv) is obtained, which decreases significantly as the diameter of the nanospheres is reduced from 260 to 129 nm. Hence, the temperature dependence of structural relaxation near the glass transition is weakened with isochoric confinement.
†Department of Chemical and Biological Engineering and ‡Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States.
Chuan
C
Zhang
†Department of Chemical and Biological Engineering and ‡Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States.
Yunlong
Y
Guo
†Department of Chemical and Biological Engineering and ‡Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States.
Kimberly B
KB
Shepard
†Department of Chemical and Biological Engineering and ‡Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States.
Rodney D
RD
Priestley
confinement; fragility; glass transition; nanoparticles; polystyrene