A decade of innovation and progress in understanding the morphology and structure of heterogeneous polymers in rigid confinement

When confined in nanoscale domains, polymers generally encounter changes in their structural, thermodynamics and dynamics properties compared to those in the bulk, due to the high amount of polymer/wall interfaces and limited amount of matter. The present review specifically deals with the confinement of heterogeneous polymers (i.e. polymer blends and block copolymers) in rigid nanoscale domains (i.e. bearing non-deformable solid walls) where the processes of phase separation and self-assembly can be deeply affected. This review focuses on the innovative contributions of the last decade (2010-2020), giving a summary of the new insights and understanding gained in this period. We conclude this review by giving our view on the most thriving directions for this topic.

Preparation and Magnetic Properties of CoFe2O4 Oriented Fiber Arrays by Electrospinning

The morphology of magnetic materials has a great influence on the properties, which is attributed to the magnetic anisotropy of the materials. Therefore, it is worth studying the fabrication of the aligned fiber and the change of its domain distribution. Nanoparticles and nanofibers were prepared by the hydrothermal and electrospinning methods, respectively. At the same time, the arranged nanofibers were collected by the drum collecting device. After the same annealing at 700 °C, it was found that the diameter of fibers collected by different collecting drums is similar. By studying the hysteresis loops of nanoarrays, it was found that they had strong anisotropy. The easy axis was parallel to the long axis, the Hc and Mr of the easy axis and the hard axis were 1330.5 Oe, 32.39 Am²/kg, and 857.2 Oe, 24.8 Am²/kg, respectively. Due to the anisotropy of the shape and the interaction between the particles, the Hc could not be enhanced. Therefore, the Ms and Hc of the nanoparticles were 80.23 Am²/kg and 979.3 Oe, respectively. The hysteresis loop and the change of magnetic moment during the demagnetization of the CoFe₂O₄ nanofiber array were simulated via micromagnetic software. The simulated Hc was 1480 Oe, which was similar to the experimental value.

Multisegmented FeCo/Cu nanowires: electrosynthesis, characterization, and magnetic control of biomolecule desorption

In this paper, we report on the synthesis of FeCo/Cu multisegmented nanowires by means of pulse electrodeposition in nanoporous anodic aluminum oxide arrays supported on silicon chips. By adjustment of the electrodeposition conditions, such as the pulse scheme and the electrolyte, alternating segments of Cu and ferromagnetic FeCo alloy can be fabricated. The segments can be built with a wide range of lengths (15-150 nm) and exhibit a close-to-pure composition (Cu or FeCo alloy) as suggested by energy-dispersive X-ray mapping results. The morphology and the crystallographic structure of different nanowire configurations have been assessed thoroughly, concluding that Fe, Co, and Cu form solid solution. Magnetic characterization using vibrating sample magnetometry and magnetic force microscopy reveals that by introduction of nonmagnetic Cu segments within the nanowire architecture, the magnetic easy axis can be modified and the reduced remanence can be tuned to the desired values. The experimental results are in agreement with the provided simulations. Furthermore, the influence of nanowire magnetic architecture on the magnetically triggered protein desorption is evaluated for three types of nanowires: Cu, FeCo, and multisegmented FeCo15nm/Cu15nm. The application of an external magnetic field can be used to enhance the release of proteins on demand. For fully magnetic FeCo nanowires the applied oscillating field increased protein release by 83%, whereas this was found to be 45% for multisegmented FeCo15nm/Cu15nm nanowires. Our work suggests that a combination of arrays of nanowires with different magnetic configurations could be used to generate complex substance concentration gradients or control delivery of multiple drugs and macromolecules.

Honeycomb porous films of pentablock copolymer on liquid substrates via breath figure method and their hydrophobic properties with static and dynamic behaviour

The peeled film obtained on the isopropanol substrate through breath figure method exhibits the best hydrophobic properties, and the water droplet impact behavior shows an obvious rebound tendency and a weak maximum spreading diameter.