Polymer nanocomposites with aligned two-dimensional materials

The use of nanomaterials with exotic mechanical and functional properties to reinforce otherwise softer and inert polymers or resins promises the development of high-performance and highly functional composite materials for advanced applications. Polymeric materials serving as matrices or substrates can translate the superior properties of different nanomaterials from nanoscale to macroscale, holding the potential to move nanomaterials from the research laboratory to tangible technological applications that revolutionize the broad plastics industry. However, even after nearly 30 years of innovative and groundbreaking research, various technical challenges still exist such as controlling the dispersion of nanomaterials in the polymer matrix during processing and the need for new synthetic concepts and processing strategies [1]. Emerging trends in 2D nanotechnology and the recent development of certain 2D materials (e.g., large-area 2D sheets and 2D heterostructures) may provide for major advancements in the field of polymer nanocomposites. The use of 2D sheets as fillers provides a means of precisely positioning nanomaterials into/onto polymer matrices/substrates with precise structural control at an atomic level, a precise control of the surface/interface layer and the distances in between the nanoinclusions, all of which are not feasible with traditional polymer nanocomposite materials. The 2D filler components have extremely high aspect ratios, which provides for maximum reinforcement at exceedingly small volume fractions. They also provide ‘multifunctional property enhancement’ and, for example, can contribute specific photoelectric or electronic functionality and mechanical reinforcement. This contribution reviews recent advances in 2D materials-based polymer nanocomposites. First, important synthetic techniques for 2D nanomaterials such as chemical vapor deposition growth and wet-chemistry are presented. Subsequently, strategies for the surface modification of 2D sheets with small molecules and polymers as well as processes for the manufacturing of polymer nanocomposites with aligned 2D inclusions are reviewed. The mechanisms of physical property enhancement are discussed and applications across a range of technology areas are presented. Finally, the challenges as well as opportunities for research in this emerging area of nanocomposite science and engineering are commented on. It is hoped that the unified perspective presented in this review will enable readers to make contributions to this exciting and rapidly advancing field.