Multiferroic polymer composites with greatly enhanced magnetoelectric effect under a low magnetic bias.

Multiferroic laminate composites consisting of chain-end cross-linked ferroelectric polymers and magnetostrictive Metglas are reported. The composites exhibit a greatly enhanced multiferroic voltage coefficient and sensitivity relative to analogous composites. These remarkable properties are attributed to high piezoelectric and electromechanical coupling coefficients, because of the formation of larger crystalline sizes and concurrent improvement in the polarization ordering in the cross-linked polymers.

A theoretical study for nanoparticle partitioning in the lamellae of diblock copolymers.

Morphology control is important for practical applications of composite materials that consist of functional polymers and nanoparticles. Toward that end, block copolymers provide useful templates to arrange nanoparticles in the scaffold of self-organized polymer microdomains. This paper reports theoretical predictions for the distribution of nanoparticles in the lamellar structures of symmetric diblock copolymers on the basis of a polymer density functional theory (DFT) and the potential distribution theorem (PDT). The DFT predicts periodic spacing of lamellar structures in good agreement with molecular dynamics simulations. With the polymer structure from DFT as the input, the PDT is used to examine the effects of particle size, surface energy, polymer chain length, and compressibility on the distribution of nanoparticles in the limit of low particle density. It is found that the nanoparticle distribution depends not only on the particle size and surface energy but also on the local structure of the microdomain interface, polymer chain length, and compressibility. The theoretical predictions are compared well with experiments and simulations.