Anisotropic Reinforcement of Nanocomposites Tuned by Magnetic Orientation of the Filler Network

TL;DR

This paper introduces a nanocomposite material with tunable anisotropic mechanical properties achieved by magnetic field-induced nanoparticle orientation during synthesis, demonstrating enhanced reinforcement along aligned chains.

Contribution

It presents a novel method to control nanocomposite anisotropy via magnetic orientation of nanoparticle networks during fabrication.

Findings

Nanoparticles form chainlike aggregates aligned by magnetic field.

Mechanical reinforcement is higher when strain is parallel to nanoparticle chains.

Strain perpendicular to chains disrupts the ordered structure.

Abstract

We present a new material which displays anisotropic and mechanical properties tuneable during synthesis under magnetic field. It is formulated by mixing aqueous suspensions of polymer nanolatex and magnetic nanoparticles, coated by a thin silica layer to improve their compatibility with the polymeric matrix, followed by casting. The magnetic properties of these nanoparticles enable their pre-orientation in the resulting nanocomposite when cast under magnetic field. Detailed insight on dispersion by Small Angle Neutron Scattering (SANS) shows chainlike nanoparticle aggregates aligned by the field on the nanometer scale. Applying strain to the nanocomposite parallel to the particle chains shows higher mechanical reinforcement, than when strain is transverse to field. . SANS from strained samples shows that strain parallel to the field induce an organization of the chains while strain perpendicular to the field destroys the chain field-induced ordering. Thus improved mechanical reinforcement is obtained from anisotropic interconnection of nanoparticle aggregates.