Effects of POSS Nanoparticles on Glass Transition Temperatures of Ultrathin Poly(t-butyl acrylate) Films and Bulk Blends

As a model system, thin films of trisilanolphenyl-POSS (TPP) and two different number average molar mass (5 and 23 kg mol(-1)) poly(t-butyl acrylate) (PtBA) were prepared as blends by Langmuir-Blodgett film deposition. Films were characterized by ellipsometry. For comparison, bulk blends are prepared by solution casting and the samples are characterized via differential scanning calorimetry. The increase in T-g as a function of TPP content for bulk high and low molar mass samples are in the order of approximate to 10 degrees C. Whereas bulk T-g shows comparable increases for both molar masses (approximate to 10 degrees C), the increase in surface T-g for higher molar mass PtBA is greater than for low molar mass (approximate to 22 degrees C vs. approximate to 10 degrees C). Nonetheless, the total enhancement of T-g is complete by the time 20 wt % TPP is added without further benefit at higher nanofiller loads. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 175-182