Incorporation Of Magnetite Nanoparticles Research Articles

Shape-memory properties of magnetically active triple-shape nanocomposites based on a grafted polymer network with two crystallizable switching segments

Thermo-sensitive shape-memory polymers (SMP), which are capable of memorizing two or more different shapes, have generated significant research and technological interest. A triple-shape effect (TSE) of SMP can be activated e.g. by increasing the environmental temperature (Tenv), whereby two switching temperatures (Tsw) have to be exceeded to enable the subsequent shape changes from shape (A) to shape (B) and finally the original shape (C). In this work, we explored the thermally and magnetically initiated shape-memory properties of triple-shape nanocompos- ites with various compositions and particle contents using different shape-memory creation procedures (SMCP). The nanocomposites were prepared by the incorporation of magnetite nanoparticles into a multiphase polymer network matrix with grafted polymer network architecture containing crystallizable poly(ethylene glycol) (PEG) side chains and poly(!- caprolactone) (PCL) crosslinks named CLEGC. Excellent triple-shape properties were achieved for nanocomposites with high PEG weight fraction when two-step pro- gramming procedures were applied. In contrast, single-step programming resulted in dual-shape properties for all investi- gated materials as here the temporary shape (A) was predominantly fixed by PCL crystallites.

Stabilization of polyaniline by the incorporation of magnetite nanoparticles

Nanocomposites obtained from the polymerization of aniline in the presence of nanoparticles of magnetite (Fe3O4) have been investigated in previous studies. However, there is a lack of information available on the redox interaction of the nanoparticle/conductive polymer couple and the stability that such an oxide can give to the organic phase. In this work, Fe3O4 nanoparticles were incorporated into a PANi matrix by the in-situ oxidative polymerization method. A combination of X-ray diffraction, Mössbauer spectroscopy, transmission electronic microscopy, UV–visible spectroscopy as well as the cyclic voltammetric and Raman spectroscopy techniques, was used to understand the redox effect that the partially oxidized nanoparticles produced on the polymer. It was found that magnetite greatly stabilised PANi, mainly by enhancing the Leucoemeraldine/Emeraldine redox couple and also by reducing the bipolaronic state.

Ordering of Fe3O4 Nanoparticles in Polyelectrolyte Multilayer Films

In our work we have focused on the incorporation of magnetite nanoparticles (NPs) into poly(allylamine hydrochloride)/poly(sodium 4-styrenesulfonate) polyelectrolyte multilayers (PEMs). The main goal of presented studies was to control the two-dimentional ordering of NPs within polyelectrolyte films. The ordering of NPs depended on the treatment of the underlying polyelectrolyte films. The NPs were uniformly distributed in freshly prepared samples leading to an interfacial mixture of polyelectrolytes and particles, while a highly concentrated layer of NP was formed only when the PEMs were exposed to elevated temperature after their preparation. The observed effect was correlated to glass-melt phase transitions of the PEMs. Such ordering of functionalized species in a polymer matrix may enhance the response from the studied nanocomposites.

Synthesis of Magnetite Nanoparticles in Mesoporous Copolymer Template: A Model System for Mass-Loading Control

Incorporation of magnetite nanoparticles in mesoporous styrene−divinylbenzene microspheres, via oxidation of ferrous ion adsorbed in the template, is modeled in terms of the ferrous ion concentration (C) and in terms of the number (N) of chemical oxidation cycles.

Preparation and Responsive Properties of Magnetically Soft Poly(N-isopropylacrylamide) Gels

A novel polymer gel characterized by temperature and magnetic field sensitivity has been prepared. By incorporation of magnetite nanoparticles into poly(N-isopropylacrylamide) hydrogels, we are able to target and separate the gel beads by a magnetic field. It was established that the presence of magnetic material does not modify the temperature sensitivity of these gels.