Thermally Switchable Periodicities and Diffraction from Novel Mesoscopically Ordered Materials.

Weissman, Jesse; Sunkara, Hari B.; Tse, A.; Asher, Sanford A.

doi:10.21236/ada314858

Cited by 7 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such a phenomenon previously reported that the reflection intensity increases monotonically but not linearly as the thickness of CC increased [17]. Since the diffraction efficiency of CC relies on the scattering cross‐section of the colloids and the ordering of the crystal, the nonlinear increasing of the reflectance might be due to the extinction phenomenon as the defects increased by adding the PC thickness [18]. Additionally, the optical photographs of the PC films are shown in Fig.…”

Section: Resultsmentioning

confidence: 88%

Ultrathin colloidal crystal layer as transparent photonic films

Chen

Dong

et al. 2019

Micro & Nano Letters

View full text Add to dashboard Cite

The study employed a facile approach to fabricate a large-area ordered robust colloidal crystal films. Poly(methyl methacrylate) colloids were dispersed and self-assembled in poly(vinyl alcohol) solution, which was then cured to form a photonic film. Such films efficiently diffract electromagnetic waves of specific wavelengths, and whose photonic band gap could be tuned from ultraviolet to visible region by changing the size of the colloids. The presented films revealed sharp diffraction and high transparency, indicating the promising applications in coating or colour filter materials.

show abstract

Section: Resultsmentioning

confidence: 88%

Ultrathin colloidal crystal layer as transparent photonic films

Chen

Dong

et al. 2019

Micro & Nano Letters

View full text Add to dashboard Cite

show abstract

“…For certain gel characteristics, these volume changes can be abrupt (volume transitions) as the control parameter is varied. We have recently exploited this kind of response in a temperature-switchable optical diffraction device consisting of a crystalline colloidal array (CCA) polymerized within a hydrogel that responds to temperature changes 13 . Such intelligent hydrogels might be used in chemomechanical systems [28][29][30] and separation devices [31][32][33] as well as sensors [34][35][36] .…”

mentioning

confidence: 99%

Polymerized colloidal crystal hydrogel films as intelligent chemical sensing materials

Holtz

Asher

1997

Nature

1,867

1,252

View full text Add to dashboard Cite

Chemical sensors respond to the presence of a specific analyte in a variety of ways. One of the most convenient is a change in optical properties, and in particular a visually perceptible colour change. Here we report the preparation of a material that changes colour in response to a chemical signal by means of a change in diffraction (rather than absorption) properties. Our material is a crystalline colloidal array of polymer spheres (roughly 100 nm diameter) polymerized within a hydrogel that swells and shrinks reversibly in the presence of certain analytes (here metal ions and glucose). The crystalline colloidal array diffracts light at (visible) wavelengths determined by the lattice spacing, which gives rise to an intense colour. The hydrogel contains either a molecular-recognition group that binds the analyte selectively (crown ethers for metal ions), or a molecular-recognition agent that reacts with the analyte selectively. These recognition events cause the gel to swell owing to an increased osmotic pressure, which increases the mean separation between the colloidal spheres and so shifts the Bragg peak of the diffracted light to longer wavelengths. We anticipate that this strategy can be used to prepare 'intelligent' materials responsive to a wide range of analytes, including viruses.

show abstract

“…In this paper, we study crystalline colloidal arrays (CCAs), highly ordered arrays of like-charged colloidal particles typically self-organized into an FCC lattice. Among the most widely experimentally studied CCAs are those comprised of monodisperse negatively charged polystyrene spheres. − The complete CCA system consists of charged colloidal particles (macroions), their counterions, salt ions, and solvent molecules. The interactions between the charged macroions are modeled via an effective DLVO pair potential.…”

Section: Introductionmentioning

confidence: 99%

“…In the first part of this paper, we use Langevin simulations to investigate the mechanism of vacancy migration in three-dimensional crystalline colloidal arrays whose particles interact through a DLVO pair potential. , In particular, we calculate the diffusion coefficient of a single vacancy. In the second part of the paper, we investigate the melting transition of the colloidal crystals of the type used in our recent experiments (S. Asher − ) by varying the DLVO potential parameters.…”

Section: Introductionmentioning

confidence: 99%

Langevin Dynamics Simulation of 3D Colloidal Crystal Vacancies and Phase Transitions

2013

View full text Add to dashboard Cite

We study the mechanism of vacancy migration and phase transitions of 3D crystalline colloidal arrays (CCA) using Langevin dynamics simulations. We calculate the self-diffusion coefficient of the colloid particles and the diffusion constant for vacancies as a function of temperature and DLVO potential parameters. We investigate the phase behavior of several systems with different interaction potential parameters using Voronoi analysis. Voronoi polyhedra tessellation, which is a useful method for characterizing the nearest neighbor environment around each atom, provides an efficient and effective way to identify phase transitions as well as geometrical changes in crystals. Using Voronoi analysis, we show that several neighboring particles are involved in the vacancy migration process that causes the vacancy to diffuse.

show abstract

Thermally Switchable Periodicities and Diffraction from Novel Mesoscopically Ordered Materials.

Cited by 7 publications

References 0 publications

Ultrathin colloidal crystal layer as transparent photonic films

Ultrathin colloidal crystal layer as transparent photonic films

Polymerized colloidal crystal hydrogel films as intelligent chemical sensing materials

Langevin Dynamics Simulation of 3D Colloidal Crystal Vacancies and Phase Transitions

Contact Info

Product

Resources

About