The effect of polystyrene blocks content and of type of elastomer blocks on the properties of block copolymer/layered silicate nanocomposites

The aim of the present work was to understand the block copolymer/layered silicate interactions as function of polystyrene blocks content and of the type of elastomer blocks in the block copolymer. Using dynamical melt intercalation method, styrene triblock copolymer/Dellite 67G nanocomposites were obtained. The properties of nanocomposites were evaluated by morphological (XRD and AFM), thermal (DSC), mechanical and dynamic mechanical (DMA) analysis. The polystyrene chains of block copolymer preferentially intercalated into the galleries of Dellite 67G and probably interacted with the surface of the silicate increasing the uniform dispersion of the silicate in the polymer matrix. Homogenous nanocomposites having ordered lamellar structure were obtained. The silicate agglomerates were split into stacks of 3-4 layers which were evenly dispersed in the polymer matrix. The block copolymer/Dellite 67G interaction was reflected in the increasing of stiffness (modulus and hardness) with maintaining of toughness, up to 30 wt.% Dellite 67G. Over 30 wt.% silicate the mechanical properties decreased, probably as result of the agglomeration of silicate particles. AFM investigation brought complementary information to XRD patterns of the nanocomposites revealing a second type of intercalated structures with interlamellar distance higher with one order of magnitude.