Nicholas Kotov1

1, University of Michigan, Ann Arbor, Michigan, United States

The notion of Nature-inspired materials is known for hundreds of years, but the challenges for transition from the replication of some geometrical parameters to purpose-driven biomimetic materials design become fully appreciated only recently. The first challenge is the ’coherent’ engineering of materials at multiple of scales spanning ten orders of dimensional organization from Ångströms to meters. The second one is simultaneous optimization of 10-15 or more materials characteristics with many of them mutually contrarian. The third one is the need to produce and integrate the optimized material into devices. This talk will cover experiment, theory, and simulations of layered graphene/graphene oxide composites that addreess these challenges.

Formation of nanocomposites with ordered layered architectures from graphene and its oxides using layer-by-layer assembly (LBL) provided the first example of self-organization that led to well-known advancements in different fields of technology. Self-assembly of anisotropic platelet-like nanoparticles of graphene afford scalable manufacturing of high performance composites for different applications. Advances in the computational description of layered biomimetic composites afford now ab ovo design and their direct synthesis using LBL and similar approaches.
Optimization of multiple parameters also required the development of new methods to combine contrarian properties in one material. Such conflicting but much needed properties are exemplified by transparency and conductivity, high strain and stiffness or high temperature resilience and elasticity. Understanding the architechture of natural materials and the role of interfaces in nanocomposite design affords new biomimetic composites with previously unknown combination of properties. The concept of kirigami composites provides a new toolbox to resolve the fundamental challenges related to multiscale structural optimization, parameter optimization, and device integration. Kirigami composites from graphene enable thermally-resistant conductors with unprecedented strains that can be used in plasma devices. Futhermore, the conductance of such layered composites become indepeendent on strain which is essential for most flexible electronic and electrooptical devices. The simplicity of computatinal design of kirigami composites with desirable properties will be highlighted. The pathway to integration of biomimetic graphene nanocomposites into the devices will be demonstrated by incorporation of ultrastrong graphene oxide kirigami sheets in the beam steeres.

Chirality is one of the essential properties of materials in Nature. Nanocarbon nanocomposites incorporating chiral multiscale structures will be demonstrated; their mechanical and optical properties will be described from experimental and computational stand points. Their integration in reconfigurable devices will be exemplified by chiroptical devices for beam steering, polarization modulation and photonics.