(86a) New Macromolecular Architectures for Crystallizable Block Copolymers

In crystallizable block copolymers, the final structure and properties can be governed by nanophase separation in the melt, block crystallization, or a combination of the two dictated by the processing history.  However, even when the block copolymer forms a homogeneous, low-viscosity melt, the block copolymer architecture can still exert substantial control over the nanoscale structure.  This talk will touch on selected aspects of crystallization in block copolymers, including two subjects of current work.  In one case, we show that through a properly-designed pentablock architecture, we can obtain a new type of thermoplastic elastomer, where microphase separation is driven by block crystallization but crystal growth is moderated by the judicious insertion of a glassy block.  In another case, we examine polydisperse polyolefin diblock copolymers synthesized at Dow Chemical, and find that the extensive mixing between the “hard” and “soft” blocks facilitated by the broad distribution of block lengths allows the crystals to grow freely and isotropically across the domain interfaces while preserving the exceptionally large-period (>100 nm) hard/soft domain structure self-assembled in the melt.