Issue 26, 2019

Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution

Abstract

We report the formation of polymeric and nanocomposite capsules via droplet solvent extraction, focusing on the interplay between solvent exchange and removal, demixing and directional solidification kinetics. We investigate a model system of sodium poly(styrene sulfonate), NaPSS and silica nanoparticles in aqueous solution, whose phase behaviour is experimentally measured, and examine a series of selective extraction solvents (toluene, butyl acetate, ethyl acetate and methyl ethyl ketone), ranging from 0.04 to 11% v/v water solubility. Tuning the rate of solvent exchange is shown to provide an effective means of decoupling demixing and solidification timescales, and thereby tunes the internal microstructure of the capsule, including hollow, microporous, core–shell, and bicontinuous morphologies. In turn, these determine the capsule dissolution mechanism and kinetics, ranging from single to pulsed release profiles of nanoparticle clusters (at intermediate solubilities), to minimal dissolution (at either extremes). These findings provide facile design and assembly strategies for functional capsules with time-varying release profiles.

Graphical abstract: Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution

Supplementary files

Article information

Article type
Paper
Submitted
08 Apr. 2019
Accepted
04 Jūn. 2019
First published
04 Jūn. 2019

Soft Matter, 2019,15, 5287-5295

Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution

C. E. Udoh, V. Garbin and J. T. Cabral, Soft Matter, 2019, 15, 5287 DOI: 10.1039/C9SM00708C

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