Hybrid Hairy Janus Particles Decorated with Metallic Nanoparticles for Catalytic Applications

Orientation Control of Hemispherical Janus Particles and Metal Coating on the Selective Surface To Excite Surface Plasmon Polaritons in the Micro-Kretschmann Geometry

Asymmetric-shaped particles (the Janus particle) are difficult to be arranged in a uniform orientation on a solid substrate. This difficulty prevents further modification of the selective surface of the particles for fabrication of the Janus particles with anisotropy of the shape and surface. We successfully arranged hemispherical particles in a uniform orientation at the air-water interface. The particles were arranged on the solid substrate in a uniform orientation by transferring the particle film onto the substrate. This arrangement enabled the fabrication of the Janus particles with anisotropy of the shape and surface by selective deposition of a film on either the equatorial plane or the spherical surface. Additionally, we demonstrated the function of the microscopic Kretschmann geometry for excitation of the surface plasmon polaritons of a thin metal film on the equatorial plane of a single hemispherical particle.

Scalable Platform for Structured and Hybrid Soft Nanocolloids by Continuous Precipitation in a Confined Environment

Geometrically structured polymer nanocolloids, including Janus nanocolloids, have been widely investigated for their unique properties, which are derived from their anisotropy. Controlled surface decoration with inorganic nanoparticles could induce another level of functionality into structured nanocolloids that could enable applications in fields ranging from rewriteable electronics to biphasic catalysis. Here, we demonstrate flash nanoprecipitation (FNP) as a one-step, scalable process platform for manufacturing hybrid polymer-inorganic nanocolloids in which one phase is selectively decorated with a metal nanocatalyst by tuning the molecular interactions between the feed ingredients during the process. For instance, by modifying the polymer end-group functionality, we document the ability to tune the location of the metal nanocatalyst, including placement at the nanocolloid circumference. Moreover, the addition of molecular additives is shown to transform the Janus nanocolloid structure from spherical to dumbbell or snowman while maintaining the ability to control the nanocatalyst location. In considering the flexibility and continuous nature of the FNP process, it offers an industrial-scale platform for the manufacturing of nanomaterials that are anticipated to impact many technologies.

Controlled and tunable design of polymer interface for immobilization of enzymes: does curvature matter?

Control and tuning of surface properties is indispensable for the programmed and rational design of materials. Particularly, polymeric brush-modified colloids can be used as carrier materials for enzyme immobilization. Although it is of prime importance to control the brush architecture, there is still a lack of systematic investigations concerning the impact of grafting density on the properties of the designed interface, as well as on the immobilization of biomolecules. In this work, we investigate the surface properties of polymer brushes with different grafting densities prepared using a "grafting from" approach on flat and on colloidal particle substrates by varying the density of initiator groups. In this way, we control and tune interfacial properties of the carrier material such as swelling, charge, adhesion as well as adsorption of laccase from Trametes versicolor on the grafted polyelectrolyte layer. We show that there is no direct transferability of the results received from planar to curved substrates regarding the swelling behavior in dependence on the grafting density. The maximum of swelling degree of PDMAEMA layers is achieved at 0.34 nm^-2 and at 0.1 nm^-2 grafting density for planar and curved particle substrates, respectively. The adhesion properties of the polymeric layer on both substrates are also strongly influenced by the grafting density, i.e. a decrease of the grafting density causes a transition from the adhesive to non-adhesive state. As proven by the cryo-TEM and AFM force distance measurements, an immobilization of laccase from Trametes versicolor causes a decrease of the polymer swelling and therefore leads to the changes in the surface morphology, charge and adhesion performance of final polymer-enzyme layer. Moreover, the higher effectiveness and activity of laccase were observed for the intermediate grafting densities which seem to be preferable over the maximum brush densities.

Preparation of Janus nanoparticles from block copolymer thin films using triazolinedione chemistry

A nanostructured thin film obtained from a polystyrene-block-poly(4-vinylpyridine) diblock copolymer was used as a template to produce Janus-type nanoparticles via triazolinedione-ene click chemistry.

Hierarchical self-assembly of protoporphyrin IX-bridged Janus particles into photoresponsive vesicles

Photoresponsive vesicles formed by PPIX-bridged Janus particles exhibited excellent photostability against intense infrared radiation and good singlet oxygen producing ability.

Programmed assembly of oppositely charged homogeneously decorated and Janus particles

The exploitation of colloidal building blocks with morphological and functional anisotropy facilitates the generation of complex structures with unique properties, which are not exhibited by isotropic particle assemblies. Herein, we demonstrate an easy and scalable bottom-up approach for the programmed assembly of hairy oppositely charged homogeneously decorated and Janus particles based on electrostatic interactions mediated by polyelectrolytes grafted onto their surface. Two different assembly routes are proposed depending on the target structures: raspberry-like/half-raspberry-like or dumbbell-like micro-clusters. Ultimately, stable symmetric and asymmetric micro-structures could be obtained in a well-controlled manner for the homogeneous–homogeneous and homogeneous–Janus particle assemblies, respectively. The spatially separated functionalities of the asymmetric Janus particle-based micro-clusters allow their further assembly into complex hierarchical constructs, which may potentially lead to the design of materials with tailored plasmonics and optical properties.