Using Interfacial Manipulations to Control Ordering In Tapered Block Copolymers

Block copolymers permit the controlled fabrication of nanoscale materials for membrane and templating applications.  To enable the increased utilization of block copolymer systems in commercial devices, additional understanding of the influence of interfacial manipulations on their bulk self-assembly is necessary.  In this work, well-controlled tapered regions are inserted between blocks in a diblock copolymer to probe the effect of interfacial composition on block copolymer self-assembly.  We systematically manipulate the interfacial region in tapered poly(isoprene-b-styrene) [P(I-S)] diblock copolymers to control ordering transitions.  In addition to locating non-lamellar-forming materials, we find that normal and inverse tapered diblock copolymers show measurable decreases in the order-disorder transition temperature (T_ODT) relative to the corresponding non-tapered diblock copolymers; with the inverse tapered materials showing the greatest deviation in T_ODT.  Additionally we have recently found the double-gyroid network morphology in several tapered diblock copolymers and show the ability to significantly reduce T_ODT’s while keeping mechanical properties nearly constant.