Related Experiment Video
Updated: Sep 22, 2025
07:42
Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
2.9K
Magnetic Field Induced Morphological Transitions in Block Copolymer/Superparamagnetic Nanoparticle Composites
Vinay Raman1, Ravi Sharma2, T Alan Hatton1
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
ACS Macro Letters
|May 24, 2022
Summary
External magnetic fields induce morphological transitions in superparamagnetic nanoparticle-polymer nanocomposites. Field orientation and nanoparticle properties control phase formation, enabling tailored material structures.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Block copolymers exhibit diverse morphologies.
- Superparamagnetic nanoparticles can influence polymer self-assembly.
- External magnetic fields offer a route to control nanostructure.
Purpose of the Study:
- Investigate magnetic field effects on nanoparticle-polymer nanocomposite morphology.
- Determine how field orientation and nanoparticle properties influence phase behavior.
- Explore the formation of ordered structures in these materials.
Main Methods:
- Two-dimensional computational study.
- Simulation of superparamagnetic nanoparticles in block copolymer melts.
- Analysis of morphological transitions under varying magnetic field conditions.
Main Results:
- In-plane fields induce nanoparticle chaining and stripe phase formation.
- Out-of-plane fields lead to defect annihilation or honeycomb lattice formation.
- Nanoparticle selectivity and field orientation dictate composite morphology.
Conclusions:
- Magnetic fields are effective tools for controlling nanocomposite structure.
- Nanoparticle properties (size, loading, selectivity) are crucial for ordering.
- Tailoring field parameters and nanoparticle characteristics enables precise morphological control.
Related Concept Videos
01:31Ferromagnetism
2.5K
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...
2.5K
01:30Paramagnetism
2.6K
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...
2.6K
01:27π Electron Effects on Chemical Shift: Overview
1.2K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.2K
03:02Colors and Magnetism
12.4K
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...
12.4K
01:26Diamagnetism
2.5K
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....
2.5K
01:23Atomic Nuclei: Nuclear Relaxation Processes
735
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
735