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

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.

Perspective: Outstanding theoretical questions in polymer-nanoparticle hybrids

“…[251][252][253][254][255][256] However, to our knowledge, only a few works have considered the corresponding phenomena when magnetic NPs are placed in a polymer matrix in an external field. 25,[257][258][259] Jestin et al, for example, incorporated iron oxide NPs in a polymer matrix in the presence of solvent (Fig. 9).…”

Magnetization and actuation of polymeric microstructures with magnetic nanoparticles for application in microfluidics

“…Other groups have investigated the influence on mechanical anisotropic reinforcement of curing a polymer filled with magnetic nanoparticles in a magnetic field [22], whereas we describe here the influence on magnetic anisotropy resulting from a similar processing. A homogeneous magnetic field ($100 mT) can align our clusters of particles and form chains of clusters.…”

Local structure of polymeric ferrogels

“…They are based on the intimate mixing of polymeric gels and magnetic particles [1,2]. Frequently, in order to mechanically reinforce the polymeric structure, the particles are aggregated [3][4][5]. The swelling of the system is then seriously hindered.…”