Matthias Arras "Controlling and Understanding the Arrangement of Carbon Nanotubes in Polymer Nanocomposites"

Carbon nanotubes (CNTs) and their polymer nanocomposites are promising materials for future applications, for example in optics or electronics. Research faces two major challenges with these outstanding nanofillers: Control over dispersion and spatial arrangement within the nanocomposite, both required to achieve optimal structure and properties of CNT based nanocomposites.

The present talk considers the alignment of CNTs, the most fundamental mode of arrangement, first. Here, the mechanism of CNT alignment in sheared polymer melts as investigated by transmission electron microscopy (TEM) in the frame work of thin melt-drawn polymer films is presented: High degrees of alignment can be found for semi-crystalline homopolymers. It highlights how specific crystallization phenomena, i.e., nanohybrid shish-kebab formation, help to align CNTs in nanocomposites based on selected semi-crystalline homopolymers.

The subsequent part of the talk addresses the problem of CNT dispersion in polymers and a solution in form of specific block-copolymers is proposed. The finding that selected block-copolymers can readily disperse CNTs very well is discussed and an explanation for this useful effect is proposed. It is demonstrated that the block-copolymer system can be used to give nanocomposites with aligned and well dispersed CNTs.

Finally, the talk will conclude with how the insight of the block-copolymer mediated CNT dispersion can be used to extend the arrangement possibilities towards more general CNT arrangement on the single-tube level. By using the self-assembly of block-copolymers in solution CNTs can be bend and fixed to polymer morphology defined shapes.