Related Experiment Video
Updated: Jun 19, 2026
08:39
Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator
Published on: January 28, 2019
10.2K
Switchable Full-Color Reflective Photonic Ellipsoidal Particles.
Qilin He1, Kang Hee Ku1, Harikrishnan Vijayamohanan1
1Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|May 28, 2020
Summary
Researchers developed switchable photonic ellipsoidal polymer particles using dendronized brush block copolymers. These particles exhibit dynamic color changes and can be controlled with magnetic fields, offering new possibilities for smart materials.
Area of Science:
- Polymer Science
- Materials Science
- Nanotechnology
Background:
- Developing tunable photonic materials is crucial for advanced optical applications.
- Self-assembly of block copolymers offers a route to complex nanostructures.
- Controlling particle morphology and photonic properties remains a challenge.
Purpose of the Study:
- To synthesize full-color reflective photonic ellipsoidal polymer particles.
- To achieve dynamic color change and magnetic field-assisted control.
- To explore the self-assembly behavior of dendronized brush block copolymers (den-BBCPs).
Main Methods:
- Solvent-evaporation self-assembly of den-BBCPs from an emulsion.
- Utilizing dendritic monomer surfactants to control interfacial properties and particle shape.
- Tuning molecular weight to control photonic color across the visible spectrum.
- Functionalizing particles with magnetic nanoparticles for on/off coloration.
Main Results:
- Spherical den-BBCP particles transitioned to striped ellipsoids.
- Rapid self-assembly yielded large domains (153 nm ≤ D ≤ 298 nm).
- Highly ordered lamellae (>100 layers) formed photonic multilayers within ellipsoids.
- Color was tunable across the visible spectrum by altering molecular weight (477–1144 kDa).
- Magnetic nanoparticles enabled real-time, switchable coloration.
Conclusions:
- Den-BBCPs self-assemble into photonic ellipsoids with tunable, dynamic color.
- Magnetic field-assisted activation provides on/off coloration control.
- These particles represent a novel class of switchable photonic materials.
More Related Videos
Related Concept Videos
01:35Light as Energy
The energy required to carry out photosynthesis is light— typically electromagnetic radiation from the sun. The range of all possible wavelengths is known as the electromagnetic spectrum.
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit less...
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit less...
02:26Photoelectric Effect
When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of light that can cause such emission of electrons is called the threshold frequency, which is specific to the metal. Light with a frequency lower than the threshold frequency, even if it is of high intensity, cannot initiate the emission of electrons. However, when the frequency is higher than the threshold value, the number of electrons ejected...
03:02Colors and Magnetism
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 eye.
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 eye.
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
01:24Color Vision
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.