Investigation of Polymer-Filler Interactions in TiO2-Filled Poly(n-alkyl methacrylates) by Low-Field NMR Relaxometry

Low-field NMR relaxometry is sensitive to molecular mobility within well-defined time windows and can thus be applied to study interactions between polymers and inorganic filler particles in composite materials. Volume fraction and dispersion of the filler influence the polymer chain dynamics, which also modify the macroscopic properties of the polymer composites. As model systems, TiO2-filled poly(n-alkyl methacrylates) with different side-chain lengths and filler contents are prepared by melt mixing. Several H-1 NMR relaxation parameters, which are sensitive and selective toward polymer-filler interactions, are investigated at a Larmor frequency of 20 MHz as a function of temperature. Both physical and empirical models are used to analyze the NMR data, and the results are compared with the aim of an unambiguous detection of polymer-filler interactions.