Concentration, Interaction and Temperature Dependent Chain Dynamics in Polybutadiene / Clay Nanocomposites Characterized by Solid State 1H Double Quantum NMR Spectroscopy

A concentration, interaction and temperature dependent multimode segmental chain dynamics of carboxyly terminated polybutadiene (CTPB) in CTPB/organo-clay (C18-clay) nanocomposite was investigated by solid state 1H double quantum (DQ) NMR spectroscopy. Here, the measurements were performed on a series of samples of CTPB physically attached to the surface of C18-clay. NMR results showed that the nanocomposite exhibit discrete dynamic component with stepwise increase in their motional freedom with decreasing clay content. A remarkable change of CTPB chain dynamics at organo-clay concentration of 40 wt{\%} was found, indicating a saturation effect of the polymer adsorbed on the clay surface. The transverse magnetization relaxation experiment help us quantitatively analysis the rigid, intermediate, and mobile components. Removal of either the end-group of CTPB or of the modifier on the clay changed the polymer-clay interaction profoundly, and thus changed polymer chain dynamics, especially for chains in proximity to the clay surface. The measurement confirmed our earlier hypothesis that the strong polymer-clay interaction was the key to the synergy effect in polymer/clay nanocomposites.