Formation process of core‐shell microparticles by solute migration during drying of homogenous composite droplets

Abstract

Abstract:Particle formation process during spray drying profoundly impacts particle morphology and microstructure. This study experimentally investigated the formation of core-shell-structured microparticles by one-step drying of composite droplets made of Eudragit ® RS (a polycationic acrylic polymer in nanoparticle form) and silica sol. The formation of an incipient surface shell was monitored using single droplet drying technique, and the freshly formed shell was recovered for subsequent analyses. Adding silica to RS precursor increased the shell formation time and altered the properties of the incipient shell from waterdispersible to non-dispersible. The incipient shell formed from RS/silica droplets with mass ratios of 1.5%:1.5% and 0.5%:2.5% showed ingredient segregation with a preferential accumulation of RS, similar to the shell region of dried microparticles. After shell formation, excess silica sol in the liquid phase could flow inwards, producing a dense core. This mobility-governed solute migration would be useful for constructing core-shell microparticles using other precursor systems.

PRODUCTION and CHARACTERIZATION of GELATIN FUNCTIONALIZED HYDROXYAPATITE COMPOSITE MICROSPHERES for BIOMEDICAL APPLICATIONS

“…Some of the SD-HA-Gel had a core-shell structure that the microgranule composed of a shell at the outer surface and a dense inherent core (Figure 3) The EDX mapping shows that Ca, P and O were enriched at the outer surface and the core of the microgranules. The formation of this morphology can be attributed to the segregation of the polymer and ceramic particles (in this case, gelatin and HA) to the outer surface of the droplet during spray drying [40]. Consequently, it can be inferred from Figure 2 and Figure 3 that the introducing of gelatin into the HA slurry led to change the cross-section morphology to a mix of hollow and core-shell microstructures.…”

Spray-Drying of Electrode Materials for Lithium- and Sodium-Ion Batteries

“…In the case of multicomponent suspensions, additional complexity is created if the different components have different particle sizes or in the case of suspension-in-solutions (Figure 3b), which may lead to distribution gradients in the dried granules. This phenomenon has not yet been studied in detail in the case of active electrode materials but other (simpler) systems have been investigated [372,373,374]. …”

Spray-drying water-based assembly of hierarchical and ordered mesoporous silica microparticles with enhanced pore accessibility for efficient bio-adsorption

“…In a water-based EISA system with a non-ionic block copolymer as the soft template, a unique chemical environment needs to be designed in order to promote self-assembly to form ordered mesostructures and to produce hierarchical structures at the same time. To achieve this purpose, based on our previous research in synthesizing core-shell microparticles, [39][40] the commercial Eudragit RS polymer, poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride), could be an attractive choice. The RS nanoparticles are water-insoluble, stably dispersible in water and ethanol-soluble.…”