Self-Assembly Behavior of Oppositely Charged Inverse Bipatchy Microcolloids.

A directed attractive interaction between predefined "patchy" sites on the surfaces of anisotropic microcolloids can provide them with the ability to self-assemble in a controlled manner to build target structures of increased complexity. An important step toward the controlled formation of a desired superstructure is to identify reversible electrostatic interactions between patches which allow them to align with one another. The formation of bipatchy particles with two oppositely charged patches fabricated using sandwich microcontact printing is reported. These particles spontaneously self-aggregate in solution, where a diversity of short and long chains of bipatchy particles with different shapes, such as branched, bent, and linear, are formed. Calculations show that chain formation is driven by a combination of attractive electrostatic interactions between oppositely charged patches and the charge-induced polarization of interacting particles.

Mono-patchy zwitterionic microcolloids as building blocks for pH-controlled self-assembly.

A directional molecular interaction between microcolloids can be achieved through pre-defined sites on their surface, "patches", which might make them follow each other in a controlled way and assemble into target structures of more complexity. In this article, we report the successful generation and characterization of mono-patchy melamine-formaldehyde microparticles with oppositely charged patches made of poly(methyl vinyl ether-alt-maleic acid) or polyethyleneimine via microcontact printing. The study of their self-aggregation behavior in solution shows that by change of pH, particle dimers are formed via attractive electrostatic force between the patchy and non-patchy surface of the particles, which reaches its optimum at a specific pH.

From 2D to 3D patches on multifunctional particles: how microcontact printing creates a new dimension of functionality.

A straightforward approach for the precise multifunctional surface modification of particles with three-dimensional patches using microcontact printing is presented. By comparison to previous works it was possible to not only control the diameter, but also to finely tune the thickness of the deposited layer, opening up the way for three-dimensional structures and orthogonal multifunctionality. The use of PEI as polymeric ink, PDMS stamps for microcontact printing on silica particles and the influence of different solvents during particle release on the creation of functional particles with three-dimensional patches are described. Finally, by introducing fluorescent properties by incorporation of quantum dots into patches and by particle self-assembly via avidin-biotin coupling, the versatility of this novel modification method is demonstrated.

Characteristics of microcontact printing with polyelectrolyte ink for the precise preparation of patches on silica particles.

This publication demonstrates the abilities of a precise and straightforward microcontact printing approach for the preparation of patchy silica particles. In a broad particle size range, it is possible to finely tune the number and parameters of three-dimensional patches like diameter and thickness using only polyethyleneimine ink, poly(dimethoxysilane) as stamp material and a suitable release solvent.

Highly efficient phase boundary biocatalysis with enzymogel nanoparticles.

The enzymogel nanoparticle made of a magnetic core and polymer brush shell demonstrates a novel type of remote controlled phase-boundary biocatalysis that involves remotely directed binding to and engulfing insoluble substrates, high mobility, and stability of the catalytic centers. The mobile enzymes reside in the polymer brush scaffold and shuttle between the enzymogel interior and surface of the engulfed substrate in the bioconversion process. Biocatalytic activity of the mobile enzymes is preserved in the enzymogel while the brush-like architecture favors the efficient interfacial interaction when the enzymogel spreads over the substrate and extends substantially the reaction area as compared with rigid particles.

Stimuli-responsive hierarchically self-assembled 3D porous polymer-based structures with aligned pores.

We have developed a novel approach for the fabrication of self-assembled porous materials with uniaxial tubular pores. The approach is based on the use of microtubes formed by stimuli-induced rolling of polymer bilayers consisting of hydrophobic and stimuli-responsive hydrophilic polymers. Different objects, for example yeast cells, can be encapsulated inside the tubes during their rolling. The self-rolled tubes filled with the yeast cells are capable of controlled self-assembly and form a uniaxial tubular homogeneously filled scaffold. Moreover, our approach allows design of porous materials with the pores having different properties.

Surfaces with self-repairable ultrahydrophobicity based on self-organizing freely floating colloidal particles.

We report an approach for the design of materials with self-repairable ultrahydrophobic properties. The materials are based on highly fluorinated crystalline fusible wax with incorporated colloidal particles. Due to the highly pronounced tendency of the wax to crystallize, the formation of blends with rough fractal surfaces was observed. In order to prove their self-repairing ability, we mechanically damaged them by scratching, which removed most of the particles from the surface. Melting of the damaged blend resulted in reorganization of the particles at the wax-air interface, restoring the initial structure and thus the ultrahydrophobic behavior.

rac-12,14-Dicyclo-propyl-5,8,13,18,21-penta-oxapenta-cyclo-[13.8.0.0.0.0]tricosa-1(15),2(11),3,9(10),16,22(23)-hexa-ene.

The mol-ecule of the title compound, C(24)H(24)O(5), has crystallographic twofold symmetry, with the central O atom lying on the rotation axis. The dihedral angle between the best planes of the benzene rings fused to the oxepine fragment is 38.5 (1)°. The dioxine ring adopts a twist form with the ethyl-ene group C atoms deviating by 0.472 (5) and -0.248 (6) Šfrom the plane defined by the remaining ring atoms.

Synthesis of robust raspberry-like particles using polymer brushes.

Synthesis of chemically and mechanically robust raspberry-like particles as well as wetting properties of coatings based on them is reported. The raspberry-like particles were prepared by immobilization of silica nanoparticles on the surface of silica microparticles coated by poly(glycidyl methacrylate) brush layer. The raspberry-like particles retain their structure after ultrasonication and exposure to organic solvents that allows their use as substrates for immobilization on polymers. Fabrication ultrahydrophobic surfaces using raspberry-like particles with immobilized poly(pentafluorostyrene) was also demonstrated.