All Publications

  • Tuning the Mechanical Properties of a Polymer Semiconductor by Modulating Hydrogen Bonding Interactions CHEMISTRY OF MATERIALS Zheng, Y., Ashizawa, M., Zhang, S., Kang, J., Nikzad, S., Yu, Z., Ochiai, Y., Wu, H., Tran, H., Mun, J., Zheng, Y., Tok, J., Gu, X., Bao, Z. 2020; 32 (13): 5700–5714
  • Inducing Molecular Aggregation of Polymer Semiconductors in a Secondary Insulating Polymer Matrix to Enhance Charge Transport CHEMISTRY OF MATERIALS Nikzad, S., Wu, H., Kim, J., Mahoney, C. M., Matthews, J. R., Niu, W., Li, Y., Wang, H., Chen, W., Toney, M. F., He, M., Bao, Z. 2020; 32 (2): 897–905
  • Multivalent Assembly of Flexible Polymer Chains into Supramolecular Nanofibers. Journal of the American Chemical Society Cooper, C. B., Kang, J., Yin, Y., Yu, Z., Wu, H. C., Nikzad, S., Ochiai, Y., Yan, H., Cai, W., Bao, Z. 2020


    Polymeric materials in nature regularly employ ordered, hierarchical structures in order to perform unique and precise functions. Importantly, these structures are often formed and stabilized by the cooperative summation of many weak interactions as opposed to the independent association of a few strong bonds. Here, we show that synthetic, flexible polymer chains with periodically placed and directional dynamic bonds collectively assemble into supramolecular nanofibers when the overall molecular weight is below the polymer's critical entanglement molecular weight. This causes bulk films of long polymer chains to have faster dynamics than films of shorter polymer chains of identical chemical composition. The formation of nanofibers increases the bulk film modulus by over an order of magnitude and delays the onset of terminal flow by more than 100 °C, while still remaining solution processable. Systematic investigation of different polymer chain architectures and dynamic bonding moieties along with coarse-grained molecular dynamics simulations illuminate governing structure-function relationships that determine a polymer's capacity to form supramolecular nanofibers. This report of the cooperative assembly of multivalent polymer chains into hierarchical, supramolecular structures contributes to our fundamental understanding of designing biomimetic functional materials.

    View details for DOI 10.1021/jacs.0c07651

    View details for PubMedID 32901473

  • Effect of Extensional Flow on the Evaporative Assembly of a Donor-Acceptor Semiconducting Polymer ACS APPLIED ELECTRONIC MATERIALS Nikzad, S., Wu, H., Wang, G., Yan, H., Schneider, S. A., Toney, M. F., Bao, Z. 2019; 1 (11): 2445–54