I. 3D Nanoscale Analysis for Soft Materials

"Seeing in 3D is believing."
 

  The key challenge in charting the synthesis-morphology-property relationship of polymeric and composite materials lies in the long-standing gap of nanoscopic morphology analysis. To bridge this gap, I integrated recent advancements in three fields: 3D electron tomography, quantitative morphometry, and machine learning. I studied a model system, polyamide membrane and prepared diverse nanoscale structure by varying a multitude of synthesis parameters. Quantitative morphometry extracted large datasets of 3D geometry descriptors. A machine learning was employed to rank the descriptors from the most to least informative to composite functionality. This newly created knowledge on nano-morphological properties was related back to bridge synthesis and functionality. The elucidation of the molecular underpinning of the synthesis–morphology–property relationship would enable a new prediction-based design of polymeric materials, advancing beyond previous “trial-and-error” approaches.

II. Polymer-Inorganic Hybrids

"Mother Nature's secret"
 

 Mother Nature has demonstrated amazing hybrid materials, which are strong, light-weight, and multifunctional, constructed from the intimate integration of organic and inorganic components. For example, organic-inorganic hybrid materials such as nacre and bone are well known for their hardness, strength, and resilience. These natural materials consist of brittle minerals connected by small amounts of biopolymer and have highly complex hierarchical structures whose properties far exceed what is obtained from simply mixing these two components together. I have aimed to unravel Mother Nature’s secrets in order to design and tailor-make multifunctional organic-inorganic hybrids. The areas of interest include flexible/structural batteries, surface-agnostic conductive coatings, and sensors.

(1) Energy Storage Materials
  Flexible batteries are essential for wearable devices and flexible electronics to become more widely available but, most currently available batteries are bulky and rigid and their components are often brittle. We solved that problem by hybridizing vanadium pentoxide (V2O5) with a conductive block copolymer, poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO), in order to fabricate a highly flexible battery cathode. The V2O5 layers were arranged in parallel and held together by the block copolymer binder in a brick-and mortar-like fashion resulting in an organic-inorganic hybrid that mimics materials found in nature. This unique structure significantly enhances mechanical flexibility and toughness without sacrificing battery capacity.

(2) Functional Conformal Coatings:
  MXenes are a new and exciting class of materials that show great promise for use in the fields of conductive coatings, however, they are lacking in mechanical performance. Using nature as inspiration, I replicated the brick-and-mortar structure of tough and resilient nacre shells using layer-by-layer assembly. This hybridization combined high conductivity, mechanical robustness, and mechanical flexibility. This addresses one of the main obstacles in functional MXene materials and composites: failure and loss of functionality at low strains (4% strain). Furthermore, these MXene multilayer coatings can be deposited on to nearly any surface, regardless of chemistry, topography, or softness. This opens up a range of applications such as human motion sensing, topographic sensors, humidity sensors, and human health monitoring devices.