Dynamically Modulating the Optical and Electrical Properties of Hybrid Materials
Abstract
Efficient modulation of functional nano-composites, as building blocks for photonic microstructures, for responsive camouflage textile, and for stealth structures relies on their ability to self-assembled and stimulated. In this research proposal, we aim to develop a synthetic method that enables the construction of deformable composites comprising cellulose nanocrystals (CNCs) that self-assemble together with carbon nanotubes(CNT) into chiral nematic liquid-crystal phase, embedded in a polyurethane matrix (PU). The composites are designed to undergo large deformations by applying mechanical stress, and rapidly revert to their original shape when the stress is relaxed. When the composite is deformed, transition occurs from chiral nematic structure into a pseudo-nematic order, while the interwoven CNTs forming a tree-dimensional conductive network. The main goal of the proposed research is to develop bulk multifunctional hybrids that exhibits responsive optics (i.e., reversible transition from nematic to chiral nematic structure) along with responsive mechanical and electrical properties. We plan to (i) develop stable and spinnable colloidal inks (CNC, CNT, PU), (ii) electrospinning of ink for preparation of fibers that will be further assembled into macroscopic objects, (iii) direct printing of structures in a multi-layered configuration with controllable structural heterogeneity, and (iv) characterize the optical, mechanical electrical responsiveness of the structures under mechanical stimulation. The cylindrical geometry (electrospun fibers) and the multi-layered structures along with the strong electrical and shear fields (used for electrospinning or 3D printing in general) are expected to improve the long range (orientational) order of the CNCs. The CNTs will serve both as processing agents (inducing confinement and shear-induced-ordering), and to improve the mechanical and electrical conductivity properties of the resulting objects. Micro structural heterogeneity, demonstrated by structural colors and reflectance wavelengths of composite films will be controlled by varying the weight ratio of CNCs, pH, ionic strength of the suspension and the applied shear forces during deposition. Mechanical properties and electrical conductivity will be locally tuned by varying the weight ratio of the CNTs. Responsiveness of the hybrid structures (CNC, CNT, Polymer matrix) will be studied by mechanically-induced stimulation which will deform (e.g., stretching, bending) the structures.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 10, 2019
- Source ID
- W911NF1910334
Entities
People
- Eyal Zussman
Organizations
- Army Contracting Command
- United States Army