Nucleation and Supercooling Mitigation in Fatty Alcohol Phase Change Material Emulsions for Heat Transport and Storage.

Organic phase change slurries (PCS) exhibit significant supercooling in small particles, which diminishes their advantages over sensible heat storage systems by reducing energy efficiency and reliability. While the mechanisms of supercooling in alkanes have been extensively studied, investigations of emulsions containing fatty alcohols are limited. This study examines the impact of nucleating agents on reducing supercooling in oil-in-water (O/W) emulsions of 1-docosanol, a fatty alcohol used as a phase change material (PCM).

Pre-trained artificial intelligence-aided analysis of nanoparticles using the segment anything model.

Complex structures can be understood as compositions of smaller, more basic elements. The characterization of these structures requires an analysis of their constituents and their spatial configuration. Examples can be found in systems as diverse as galaxies, alloys, living tissues, cells, and even nanoparticles.

Phase behaviour in 2D assemblies of dumbbell-shaped colloids generated under geometrical confinement.

The structure formation and the phase behaviour of monolayers of dumbbell-shaped colloids are explored. For this, we conduct Langmuir-Blodgett experiments at the air/water interface and conventional Brownian dynamic simulations without hydrodynamic interactions. Using Voronoi tessellations and the probability density of the corresponding shape factor of the Voronoi cells p(ζ), the influence of the area fraction φ on the structure of the monolayers is investigated.

Direct Measurement of Sedimentation Coefficient Distributions in Multimodal Nanoparticle Mixtures.

Differential centrifugal sedimentation (DCS) is based on physical separation of nanoparticles in a centrifugal field prior to their analysis. It is suitable for resolving particle populations, which only slightly differ in size or density. Agglomeration presents a common problem in many natural and engineered processes.

Zonal rotor centrifugation revisited: new horizons in sorting nanoparticles.

Density gradient centrifugation is an effective method for the isolation and purification of small particles. Hollow rotors capable of hosting density gradients replace the need for centrifuge tubes and therefore allow separations at large scales. So far, zonal rotors have been used for biological separations ranging from the purification of whole cells down to serum proteins.

Experimental Assessment and Model Validation on How Shape Determines Sedimentation and Diffusion of Colloidal Particles.

Understanding the hydrodynamics of colloids with complex shapes is of equal importance to widespread practical applications and fundamental scientific problems, such as gelation, crystallization, and phase behavior. Building on previous work, we present a comprehensive study of sedimentation, diffusion, intrinsic viscosities, and other shape-dependent quantities of clusters built from spherical nanoparticles. Cluster preparation is accomplished by assembling surface-modified polystyrene particles on evaporating emulsion droplets.

Shape-tailored polymer colloids on the road to become structural motifs for hierarchically organized materials.

Anisometric polymer colloids are likely to behave differently when compared with centrosymmetric particles. Their study may not only shine new light on the organization of matter; they may also serve as building units with specific symmetries and complexity to build new materials from them. Polymer colloids of well-defined complex geometries can be obtained by packing a limited number of spherical polymer particles into clusters with defined configurations.

Salt-regulated attraction and repulsion of spherical polyelectrolyte brushes towards polyelectrolyte multilayers.

Adsorption of colloidal particles presents an interesting alternative to the modification of surfaces using covalent coupling or physisorption of molecules. However, to tailor the properties of these materials full control over the effective particle-substrate interactions is required. We present a systematic investigation of the adsorption of spherical polyelectrolyte brushes (SPB) onto polyelectrolyte multilayers (PEM).

Monte Carlo computer simulations and electron microscopy of colloidal cluster formation via emulsion droplet evaporation.

We consider a theoretical model for a binary mixture of colloidal particles and spherical emulsion droplets. The hard sphere colloids interact via additional short-ranged attraction and long-ranged repulsion. The droplet-colloid interaction is an attractive well at the droplet surface, which induces the Pickering effect.

Nanoreactor-assisted polymerization toward stable dispersions of conductive composite particles.

We demonstrate the functioning of a macromolecular nanoreactor which guides a reaction in a confined volume and leads toward improved functional properties of a product material. In our approach, the polymerization of aniline (ANi) is conducted within the interfacial volume of spherical polyelectrolyte brushes (SPB) which are densely affixed to colloidal particles. The SPB provide optimal conditions for matrix polymerization by the efficient confinement of ANi monomers within the finite volume of polyelectrolyte brushes and controlled delivery of the oxidizing reagent to the reaction volume.

Towards nanoscale composite particles of dual complexity.

The fabrication of heteroaggregates comprising inorganic and organic nanoparticles of different sizes is reported. Control over the assembly of nanoscale functional building units is of great significance to many practical applications. Joining together different spherical nanoparticles in a defined manner allows control over the shape of the composites.

Glycopolymer-grafted polystyrene nanospheres.

The synthesis and characterization of spherical sugar-containing polymer brushes consisting of PS cores onto which chains of sugar-containing polymers have been grafted via two different techniques are described. Photopolymerization in aqueous dispersion using the functional monomer MAGlc and crosslinked or non-crosslinked PS particles covered with a thin layer of photo-initiator yielded homogeneous glycopolymer brushes attached to spherical PS cores. As an alternative, ATRP was used to graft poly-(N-acetylglucosamine) arms from crosslinked PS cores.

Adsorption of beta-lactoglobulin on spherical polyelectrolyte brushes: direct proof of counterion release by isothermal titration calorimetry.

The thermodynamics and the driving forces of the adsorption of beta-lactoglobulin on spherical polyelectrolyte brushes (SPB) are investigated by isothermal titration calorimetry (ITC). The SPB consist of a polystyrene core onto which long chains of poly(styrene sulfonate) are grafted. Adsorption isotherms are obtained from measurements by ITC.

Enhanced activity of enzymes immobilized in thermoresponsive core-shell microgels.

We present a quantitative study of the catalytic activity of beta-d-glucosidase from almonds adsorbed on thermosensitive microgels. The core-shell particles used as a carrier system consist of a solid polystyrene core onto which a poly(N-isopropylacrylamide) (PNiPA) network is grafted. In the swollen state of this microgel, i.

3D Brownian diffusion of submicron-sized particle clusters.

We report on the translation and rotation of particle clusters made through the combination of spherical building blocks. These clusters present ideal model systems to study the motion of objects with complex shape. Since they could be separated into fractions of well-defined configurations on a sufficient scale and because their overall dimensions were below 300 nm, the translational and rotational diffusion coefficients of particle doublets, triplets, and tetrahedrons could be determined by a combination of polarized dynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS).

Supramolecular Structures Generated by Spherical Polyelectrolyte Brushes and their Application in Catalysis.

We survey recent studies on composite particles made from spherical polyelectrolyte brushes (SPB) and catalytically active nanoparticles or enzymes. SPB consist of a solid core (diameter: ca. 100 nm) onto which long chains of anionic or cationic polyelectrolyte (PE) are densely grafted ("PE brush").

Preparation of submicrometer-sized clusters from polymer spheres using ultrasonication.

The fabrication of small assemblies of spherical colloidal particles is presented. Basic principles of the preparation of miniemulsions were combined with the concept originally described by Pine and co-workers for the preparation of clusters from microspheres. The application of ultrasonic emulsification limits the size distribution of the emulsion droplets and thus the statistical distribution of the number of particles per droplet.

Directed motion of proteins along tethered polyelectrolytes.

We present the first time-resolved investigation of motions of proteins in densely grafted layers of spherical polyelectrolyte brushes. Using small-angle x-ray scattering combined with rapid stopped-flow mixing, we followed the uptake of bovine serum albumin by poly(acrylic acid) layer with high spatial and temporal resolution. We find that the total amount of adsorbed protein scales with time as t(1/4).

Adsorption of bovine hemoglobin onto spherical polyelectrolyte brushes monitored by small-angle X-ray scattering and Fourier transform infrared spectroscopy.

The adsorption of bovine hemoglobin (BHb) onto colloidal spherical polyelectrolyte brushes (SPBs) is studied by a combination of small-angle X-ray scattering (SAXS) and Fourier transform infrared spectroscopy (FTIR). The SPBs consist of a polystyrene core onto which long chains of poly(styrene sulfonic acid) are grafted. Hemoglobin is a tetrameric protein that disassembles at low pH's and high ionic strengths.

Biocompatible polymer vesicles from biamphiphilic triblock copolymers and their interaction with bovine serum albumin.

The self-assembly of the biamphiphilic triblock copolymer poly(ethylene oxide)-b-poly(caprolactone)-b-poly(acrylic acid) into polymer vesicles is studied. The vesicles provide both biocompatibility and biodegradability. Moreover, the biamphiphilic nature of the triblock copolymer provides different surface properties in the interior and in the outer interface of the vesicles.

Polyelectrolyte-mediated protein adsorption: fluorescent protein binding to individual polyelectrolyte nanospheres.

We have used confocal fluorescence microscopy with single molecule sensitivity to characterize uptake and release of fluorescent protein (mEosFP) molecules by individual spherical polyelectrolyte brush (SPB) nanoparticles that were immobilized on a glass surface. The SPB particles consisted of a solid core particle of 100 nm diameter onto which long polyelectrolyte chains were affixed. They could be loaded with up to 30 000 mEosFP molecules in a solvent of low ionic strength.

A modified box model including charge regulation for protein adsorption in a spherical polyelectrolyte brush.

Recent experiments showed significant adsorption of bovine serum albumin (BSA) in spherical polyelectrolyte brushes (SPB) consisting of polyacrylic acid, even for pH values above the isoelectric point of the protein, when both protein and polyion are negatively charged. To describe these experimental findings theoretically, we have constructed a spherical box model for an annealed brush consisting of a weak polyelectrolyte that includes the adsorption of BSA. At equilibrium the chemical potential of BSA in solution equals that at each location in the brush, while the net force on the polyions (including osmotic, stretching, and excluded volume terms) is zero at each location.

High elongation of polyelectrolyte chains in the osmotic limit of spherical polyelectrolyte brushes: a study by cryogenic transmission electron microscopy.

We investigate the conformation of long polyelectrolyte chains attached to colloidal latex particles by cryogenic transmission electron microscopy (cryo-TEM). The dense grafting of the polyelectrolyte chains ("polyelectrolyte brush") leads to a confinement of the counterions and a concomitantly high osmotic pressure within the polyelectrolyte layer attached to the core particles. Cryo-TEM has provided first model-independent direct proof for the strong stretching of the polyelectrolyte chains by direct visualization.