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Published on: February 13, 2016
Bimodal swelling responses in microgel thin films.
Courtney D Sorrell1, L Andrew Lyon
1School of Chemistry and Biochemistry & Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
The Journal of Physical Chemistry. B
|April 5, 2007
Summary
Researchers studied pH-responsive microgel thin films using advanced microscopy and spectroscopy. Film architecture and pH significantly alter optical and mechanical properties, revealing insights into swelling and de-complexation.
Area of Science:
- Materials Science
- Polymer Science
- Surface Chemistry
Background:
- Microgel thin films offer tunable properties for various applications.
- Understanding their response to environmental stimuli like pH is crucial for material design.
Purpose of the Study:
- To investigate the impact of film architecture and solution pH on the properties of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) microgel thin films.
- To elucidate the relationship between microgel-PAH interactions and pH-dependent film behavior.
Main Methods:
- Utilized quartz crystal microgravimetry (QCM), surface plasmon resonance (SPR), and atomic force microscopy (AFM).
- Employed spin-coating layer-by-layer (scLbL) assembly with poly(allylamine hydrochloride) (PAH) as a polycationic binder.
Main Results:
- Film architecture and pH significantly influence optical and mechanical properties.
- QCM and SPR responses show marked changes with pH variations, indicating pH-dependent swelling.
- Observed effects attributed to combined particle swelling and polyelectrolyte de-complexation.
Conclusions:
- The interaction between negatively charged microgels and positively charged PAH is critical for pH responsiveness.
- These findings enhance the understanding of morphological changes in environmentally responsive microgel thin films.
