TY - JOUR
T1 - Ultrathin Polymer Films: Rubbery Stiffening, Flagility, and T-g Reduction
AU - Li, Xiguang
AU - McKenna, Gregory
PY - 2015/9
Y1 - 2015/9
N2 - The mechanical and viscoelastic responses of poly(ethyl methacrylate) (PEMA) ultrathin films over thicknesses ranging from 21 to 112 nm have been studied using a nanobubble inflation method. The stress strain response of the PEMA thin films shows a rubbery stiffening as the film thickness decreases, and the present results are combined with prior measurements of the rubbery stiffening index S for multiple polymers. We find that S is linearly correlated with the dynamic fragility index m. The results are also consistent with expectation from Ngai et al.'s [J. Polym. Sci, Part B: Polym. Phys. 2013, 51 (3)] recent proposition based on his coupling, model but do not seem to correlate with the molecular composite concept proposed, by Page et al. [Nano Lett. 2014, 14 (5)] as a means to explain the dependence of the rubbery stiffening on chemical structure of the polymer. In addition, we observe a reduction in glass transition temperature of as much as 15.7 K for PEMA films of 21 nm thicknes
AB - The mechanical and viscoelastic responses of poly(ethyl methacrylate) (PEMA) ultrathin films over thicknesses ranging from 21 to 112 nm have been studied using a nanobubble inflation method. The stress strain response of the PEMA thin films shows a rubbery stiffening as the film thickness decreases, and the present results are combined with prior measurements of the rubbery stiffening index S for multiple polymers. We find that S is linearly correlated with the dynamic fragility index m. The results are also consistent with expectation from Ngai et al.'s [J. Polym. Sci, Part B: Polym. Phys. 2013, 51 (3)] recent proposition based on his coupling, model but do not seem to correlate with the molecular composite concept proposed, by Page et al. [Nano Lett. 2014, 14 (5)] as a means to explain the dependence of the rubbery stiffening on chemical structure of the polymer. In addition, we observe a reduction in glass transition temperature of as much as 15.7 K for PEMA films of 21 nm thicknes
U2 - 10.1021/acs.macromol.5b01263
DO - 10.1021/acs.macromol.5b01263
M3 - Article
SP - 6329
EP - 6336
JO - Macromolecules
JF - Macromolecules
ER -