Nanofillers

Nanofillers are nanoscale additives used to enhance the properties of a host material, typically polymers. They have at least one dimension in the nanometer range, and are designed to interact with the matrix to improve mechanical, thermal, barrier, or electrical properties.

Common nanofillers include carbon-based nanomaterials such as carbon nanotubes and graphene; layered silicates such as nanoclays; inorganic oxide nanoparticles such as silica; and natural or bio-based fillers like nanocellulose. Other examples include boron nitride nanotubes and titania nanoparticles. Their effects depend on size, shape, surface chemistry, and how well they disperse within the matrix.

The improvements arise from mechanisms such as load transfer from the matrix to stiff filler, formation of percolating networks for electrical or thermal conductivity, and the creation of a tortuous path that slows diffusion of gases, liquids, or heat. Dispersion quality and interfacial bonding are critical, as agglomeration or poor adhesion can negate benefits.

Processing methods include melt compounding, solution mixing, and in situ polymerization. Surface functionalization or compatibilization is often used to enhance dispersion and adhesion and to tailor interactions with the matrix.

Applications span polymer composites for automotive and aerospace, coatings, dental materials, electronics, energy storage, and membranes. Challenges include achieving uniform dispersion, avoiding filler agglomeration, cost considerations, and safety and environmental impacts related to nanoscale materials.