Related Experiment Video
Updated: Jan 8, 2026
07:42
Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
3.2K
Low-Intensity Magnetic-Field-Directed Lattice Symmetry Transition to Induce the Centered Rectangular Cylinders in
Wen-Hong Li1, Wen-Sheng Chiu1, Che-Yi Chu1
1Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
ACS Macro Letters
|December 16, 2025
Summary
Researchers controlled block copolymer lattice symmetry using low-intensity magnetic fields. This method tunes nanostructure, offering precise control over material properties by manipulating magnetic nanoparticles within the polymer matrix.
Area of Science:
- Materials Science
- Polymer Chemistry
- Nanotechnology
Background:
- Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers exhibit ordered nanostructures.
- Controlling lattice symmetry is crucial for tailoring material properties.
- Magnetic nanoparticles can influence polymer self-assembly.
Purpose of the Study:
- To demonstrate a strategy for controlling lattice symmetry in PS-b-PMMA.
- To investigate the effect of low-intensity magnetic fields on block copolymer morphology.
- To explore the use of magnetic nanoparticles as a tool for nanostructure manipulation.
Main Methods:
- Hybridizing PS-b-PMMA with NH2-tethered Fe3O4 magnetic nanoparticles.
- Applying large-amplitude oscillatory shear alignment.
- Exposing to a low-intensity magnetic field (350 mT) post-shear or to unoriented samples.
Main Results:
- Shear-aligned hexagonally packed cylinders (HEX) transformed into centered rectangular cylinders (CR) under magnetic field.
- Magnetic field applied to unoriented HEX induced reorganization into lamellae parallel to the field.
- CR phase is a kinetically stabilized metastable structure, while lamellae represent the thermodynamic equilibrium.
Conclusions:
- Low-intensity magnetic fields can effectively tune block copolymer lattice symmetry.
- Microdomain reorientation driven by magnetic fields relieves polymer chain stress.
- This noncontact magnetic manipulation offers a novel method for controlling nanostructures in block copolymers.
More Related Videos
06:49Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates
Published on: April 12, 2019
8.1K
11:42Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers
Published on: June 20, 2019
8.2K
Related Concept Videos
01:26Diamagnetism
2.9K
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
2.9K
01:30Paramagnetism
2.9K
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
2.9K
01:14Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
1.4K
An applied magnetic field causes the electrons present in the molecule to circulate, setting up a local diamagnetic current within the molecule. The local diamagnetic current arising from circulating sigma-bonding electrons induces a magnetic field, Blocal that opposes the applied magnetic field, B0. The effective magnetic field experienced by these nuclei is given by the difference between the applied and local magnetic fields in a phenomenon called local diamagnetic shielding. Essentially,...
1.4K
03:02Colors and Magnetism
13.9K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
13.9K
01:31Ferromagnetism
2.9K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.9K
01:05Atomic Nuclei: Magnetic Resonance
1.1K
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
1.1K