Supplemental Information For:
Polyelectrolye Exchange and Diffusion in Microgel Multilayer Thin Films
Emily S. Hermana and L. Andrew Lyon*a,b
aSchool of Chemistry and Biochemistry and the Petit Institute for Bioengineering and
Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
bSchmid College of Science and Technology, Chapman University, Orange, CA 92866, USA
*Corresponding Author
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Phone: (714) 997-6930
Film thickness measurements
The thickness of the swollen microgel films was analyzed by in-liquid AFM using an Asylum Research MFP-3D AFM (Santa Barbara, CA). For in-liquid imaging, Asylum Research iDrive cantilevers were used (Force Constant = 0.09 N/m). Films were assembled on glass coverslips as described in the manuscript, and a scratch was made with a straight edge razor to expose the glass surface. The film-modified coverslips were attached to a glass microscope slide using silver paint and samples were allowed to equilibrate in HIS PBS for approximately 30 min. Films were then imaged with the scan direction perpendicular to the scratch with a scan size of 50 µm to allow for analysis of film height on either side of the scratch. MFP-3D software written in the IgorPro (WaveMetrics Inc., Lake Oswego, OR) environment was used to analyze the height of films by drawing line traces across 4 height maps of scratched regions.
Figure S1. In-liquid AFM images of PLL10-microgel11 films with PLL*1 (a) PLL*5 (b) and PLL*10 (c). The heights of the films were calculated from line scans, and representative line scans for a, b, and c are shown in d (1.1 ±0.2 µm), e (0.9±0.2 µm) and f (1.3±0.2 µm), respectively.
Film Deformation and Healing
To assess the ability of microgel films composed with PLL to damage and heal, microgel films were constructed on an elastomeric substrate and were stretched by 10%, and healed upon exposure to water and subsequent drying. Films before and after damage as well as after healing were analyzed by Atomic Force Microscopy (AFM) using a Nanosurf (Boston, MA) Easyscan 2. Cantilevers used were aluminum coated silicon ACLA cantilevers (Force Constant = 45 N/m) purchased from AppNano (Santa Clara, CA).
Figure S2. AFM images of PLL-microgel films before a uniaxial strain (10%) (a), after application of a 10% uniaxial strain (b), and after healing in water (c). Images are 20 × 20 µm. Areas outside of optimal imaging resolution are designated in red (high areas) and blue (low areas).