Interfacial adhesion of nanoparticles in polymer blends by intrinsic fluorescence spectra

Intrinsic fluorescence was applied to quantitatively describe the interfacial adhesion of nanoparticles in poly-styrene/poly(vinyl methyl ether) (PS/PVME) blends. Due to the aggregation of aromatic rings on PS chains, the temperature dependence of excimer fluorescence intensity (I(324)) showed the high sensitivity to the phase separation process. Consistent with Ginzburg thermodynamic model, it was found that the addition of spherical hydrophilic nanoparticles shifted the phase separation temperature to higher temperatures due to the aggregation of silica into PVME chains leading to the free energy reduction and slowing down the phase separation dynamics. A certain composition of polymer blend, i.e. 2/8, was focused on to shed light on the dynamic of spinodal decomposition (SD) phase separation by using decomposition reaction model. It was shown that the addition of nanoparticles to polymer blends resulted in the deviation of linear relationship between the initial SD phase separation rate (R(p0)) and thermodynamic driving force (Delta f(SD)). Besides, for PS/PVME (2/8) with 2 vol% silica nanoparticles, the apparent activation energy of phase separation (E(a)) was 196.61 kJ/mol, which was higher than that of neat PS/PVME (2/8) blend (E(a) = 173.68 kJ/mol), which strongly confirmed the interfacial adhesion effect of silica nanoparticles as compatibilizers.