Measuring microgel swell ratio by cryo-SEM

Jing Liang, Feiyue Teng, Tseng Ming Chou, Matthew Libera

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The swell ratio is a key parameter characterizing the structure and properties of a hydrogel. In macroscopic gels, the swell ratio can be determined by straightforward measurements of the gel weight in the dry and hydrated states. However, measuring the swell ratio characteristic of microgels (gel particles with dimensions of 0.1–100 μm) is substantially more challenging because of their small size and polydispersity. We use cryo-scanning electron microscopy (cryo-SEM) to measure microgel diameter both in the frozen-hydrated and fully dry states using pH-responsive poly(ethylene glycol)-co-acrylic acid microgels. The volume swell ratios characteristic of the various microgels are essentially the same as those measured from otherwise-identical macroscopic gels. Hence we can conclude that, at least in this case where the macroscopic gel and microgel synthesis methods are similar, the simple measurement of a macroscopic swell ratio provides a reasonable approximation to the microgel swell ratio.

Original languageEnglish
Pages (from-to)1-4
Number of pages4
JournalPolymer
Volume116
DOIs
StatePublished - 5 May 2017

Keywords

  • Cryo-SEM
  • Microgel
  • Swell ratio

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