Cover Picture: Macromol. Mater. Eng. 2/2004

Egen, M.; Braun, Lydia; Zentel, Rudolf; Tännert, Klaus; Frese, Peter; Reis, Oliver; Wulf, M.

doi:10.1002/mame.200490003

Cited by 7 publications

(12 citation statements)

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“…[5,6] Three-dimensional photonic crystals for the visible range are mostly prepared by the self-assembly of preformed objects. The constituent beads are SiO 2 or, more recently, polymer colloids of some hundred nanometers in diameter, which are crystallized into a face centered cubic lattice and dried (empty interstices).…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14] Polymer opals were, at the beginning, prepared from polystyrene colloids. By the use of different monomers, it was possible to vary the thermal stability [5,14,15] (internal crosslinking), the refractive index (fluorinated monomers), [5] to allow post-crystallization processing by E-beam lithography [11,16] and much more. For this purpose a large variety of methacrylates has been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Surfactant‐Free Emulsion Polymerization of Various Methacrylates: Towards Monodisperse Colloids for Polymer Opals

Egen

Zentel

2004

Macro Chemistry & Physics

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Summary: A systematic investigation of the surfactant‐free emulsion polymerization (SFEP) on three different methacrylates (MMA, tert‐butyl methacrylate and 2,2,2‐trifluoro ethyl methacrylate) is described to obtain monodisperse colloids for the preparation of artificial “polymer opals”. The experimental results are in agreement with a model, in which seed particles are formed very early during the polymerization process. The particles grow afterwards into the colloids until all monomer is consumed. This gives rise to a linear relationship between the volume of the colloids and the ratio of monomer to water in the reaction batch. The concentration of the seed particles depends thereby on the hydrophobicity of the monomers and can be varied by the addition of salt. The relationship between the composition of the reaction batch and the size of the colloids differs from monomer to monomer. It can, however, be described for all systems by the introduction of an empirical system dependent parameter pM (master curve). It is thus possible to predict the colloidal size for new monomer (or salt) systems from a single measurement point. Colloids with a diameter of more than 500 nm can be prepared by a two stage seeded polymerization. The colloids prepared with this method are so monodispersed (well below 5%) that they can easily be crystallized into artificial polymer opals of a high optical quality.Dried opaline films (second‐order reflection).magnified imageDried opaline films (second‐order reflection).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surfactant‐Free Emulsion Polymerization of Various Methacrylates: Towards Monodisperse Colloids for Polymer Opals

Egen

Zentel

2004

Macro Chemistry & Physics

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“…To this end, Egen and coworkers deposited photonic crystal fi lms using fl uorinated PMMA and relied on the natural tendency of the fi lm to fracture into fl akes during drying (Figure 6 b, top left). [ 55 ] The resulting photonic structures could be stabilized against disintegration on redispersal and suspensions of them displayed striking colors due to the angular dependence of their transmission band (Figure 6 b, bottom left and top right). When these fl akes were deposited on a steel substrate a variety of colors could be obtained, depending on the diameter of the spheres contained within the fl akes (Figure 6 b, bottom right).…”

Section: Studies Assuming Predominantly Spherical Particlesmentioning

confidence: 97%

Painting by Numbers: Nanoparticle‐Based Colorants in the Post‐Empirical Age

et al. 2011

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The visual appearance of the artificial world is largely governed by films or composites containing particles with at least one dimension smaller than a micron. Over the past century and a half, the optical properties of such materials have been scrutinized and a broad range of colorant products, based mostly on empirical microstructural improvements, developed. With the advent of advanced synthetic approaches capable of tailoring particle shape, size and composition on the nanoscale, the question of what is the optimum particle for a certain optical property can no longer be answered solely by experimentation. Instead, new and improved computational approaches are required to invert the structure-function relationship. This progress report reviews the development in our understanding of this relationship and indicates recent examples of how theoretical design is taking an ever increasingly important role in the search for enhanced or multifunctional colorants.

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“…The use of reactive monomers allows for chemical modification of the spheres after crystallization, while crosslinking can be employed generally to increase the thermal and mechanical stability as well as resistance towards solvents (see Scheme 1 and ref. [13,14] for comparison).…”

Section: Communicationmentioning

confidence: 99%

“…Slight modification of the conditions of the emulsion polymerization used for the fabrication of monodisperse polymer colloids allows for the synthesis of monodisperse polymer colloids from various acrylate monomers. [11,12] Compared to their inorganic equivalents, polymer colloids offer the advantage that they allow for facile tailoring of many material properties, such as glass transition temperature [13] or refractive index [14] by simple use of differently functionalized monomers as starting material. Inorganic colloids are generally attractive, because they offer increased thermal stability and resistance towards organic solvents.…”

Section: Communicationmentioning

confidence: 99%

Functional Polymer‐Opals from Core–Shell Colloids

Lange

Metz

Tahir

et al. 2007

Macromol. Rapid Commun.

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Colloidal photonic crystals were prepared from monodisperse core–shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core–shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His‐tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric acid onto the core–shell colloids.magnified image

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Cover Picture: Macromol. Mater. Eng. 2/2004

Cited by 7 publications

References 0 publications

Surfactant‐Free Emulsion Polymerization of Various Methacrylates: Towards Monodisperse Colloids for Polymer Opals

Surfactant‐Free Emulsion Polymerization of Various Methacrylates: Towards Monodisperse Colloids for Polymer Opals

Painting by Numbers: Nanoparticle‐Based Colorants in the Post‐Empirical Age

Functional Polymer‐Opals from Core–Shell Colloids

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