3-DIMENSIONAL SELF-ASSEMBLY OF RODCOIL COPOLYMER NANOSTRUCTURES

We have used electron tomography to characterize the self-assembly of nanostructures formed by rodcoil copolymers. The rodcoil copolymers us ed contained a perfectly monodisperse rod segment prepared by stepwise synthesis. The chemical compound rod segment is, in turn, covalently linked at one terminus to an end-functionalized polyisoprene segment p repared by living polymerization. We found that rodcoil molecules with rod volume fraction equal to 0.36 self-assemble into long strips with a nanoscale cross section. At lower rod volume fractions, the rodcoil molecules self-assemble into supramolecular aggregates with nanoscale x,y,z dimensions. Interestingly, the nanostructures organize into dis crete layers of uniform thickness, containing in some cases a hexagona l 2D superlattice of rodcoil aggregates. Furthermore, nanostructures w ere found to self-assemble in all cases with three-dimensional order a cross the layers. The unique three-dimensional order observed in multi layers of the nanostructures must originate in the anisotropic aggrega tion of rod segments and the consequent space filling requirements as well as coil entropic penalties.