These 3d prints of gyroid and cylinder structures represent two types of patterns that “block copolymer” materials can exhibit on the nanoscale.   Most of the polymers/plastics around us are composed of repeating identical molecules known as monomers joined together in a long chain.  A polymer compound composed of different monomers is known as a block copolymer.  The physical structure and function of the block copolymer is due to the chemistry of these individual monomers, and small changes in the composition of pieces of the chain can lead to very different structures such as those printed here!

Many scientists at the Materials Research Lab are “computational chemists”, meaning they calculate and model the physical structure of these compounds on computers before doing actual lab experiments.  MRL scientists are particularly interested in gyroid structures due to their advantages in applications such as nanoporous membranes used in filtration, as nanoscale patterning devices and as charge carriers in polymer (flexible) solar cells.

Modifications to polymer chemistry (the actual arrangement of atoms that make up the polymer chains), can be used to engineer plastics that are capable of self-assembling into flexible plastic solar cells. The most successful strategy for fabricating these devices has been to blend together two different polymers (different polymer chemistries) that self-assemble into bicontinuous networks which provide pathways for oppositely charged charge carriers to be collected at opposite electrodes. The performance of these devices, referred to as bulk heterojunction (BHJ) solar cells, are governed by their organization on <5nm length scales. The 3D model of the BHJ device (printed in green in the pictures above) was printed from actual experimental data taken using Transmission Electron Microscopy Tomography, the highest resolution microscopy technique currently available to scientists.