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

Nan Fu, Winston Duo Wu, Zhangxiong Wu, Fei Tzhung Moo, Meng Wai Woo, Cordelia Selomulya, Xiao Dong Chen

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14 Citations (Scopus)


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 water-dispersible to nondispersible. 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 inward, producing a dense core. This mobility-governed solute migration would be useful for constructing core-shell microparticles using other precursor systems.

Original languageEnglish
Pages (from-to)3297-3310
Number of pages14
JournalAIChE Journal
Issue number8
Publication statusPublished - 1 Mar 2017


  • Drying-induced assembly
  • Ingredient segregation
  • Particle formation
  • Particle morphology
  • Single droplet drying

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