77. Hemingway, Melinda G.; Gupta,
Ram B.; Elton, David J. Hydrogel
Nanopowder Production by Inverse-Miniemulsion Polymerization and Supercritical
Drying. Industrial & Engineering
Chemistry Research (2010), 49(20),
10094-10099.
Abstract
Hydrogel nanoparticles can be successfully produced
by polymn. in inverse miniemulsions, for use in a variety of applications including
diagnosis, drug delivery, sepn., soil stabilization, and absorption. Unfortunately, conventional drying techniques
result in agglomerated powder due to the sticky nature of the wet hydrogel
particles. This work utilizes supercrit.
CO2 drying to obtain free-flowing hydrogel nanoparticles. Polyacrylamide hydrogel nanoparticles
(.apprx.100 nm in diam.) are produced in an inverse miniemulsion composed of a
cyclohexane continuous phase, a water dispersed phase, and a nonionic
surfactant. The polymd. miniemulsion is
dried by injection into supercrit. CO2 which results in rapid removal of
cyclohexane, water, and surfactant. The
morphol., particle size, and size distribution of the nanoparticles are detd.
using dynamic light scattering and SEM.
The proposed miniemulsion polymn. supercrit. drying (MPSD) method
produces a hydrogel nanopowder with much lower agglomeration or residual
surfactant as compared to convention drying.
In addn., the MPSD method produced solvent-free nanoparticles due to
efficient extraction by supercritical CO2.
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