fabrication of stable, anisotropic microcapsules€¦ · huda a. jerri [email protected] advisor:...
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Huda A. [email protected]
Advisor: Darrell [email protected]
Fabrication of Stable,Anisotropic Microcapsules
Funding: National Science Foundation (CBET Grant #0651611)
hole
Particle Lithography Key to Anisotropic Assemblies
Snyder, C. et al (Velegol). Langmuir 2005, 21, 4813-4815
Dual-Functionalized Particles by Particle Lithography
Yake, A. et al (Velegol). Biomacromolecules 2007, 8,1958-1965
Plan A: Processing Dye-Loaded Capsules
Initial Plan: form, load, settle capsules and lithograph
pH pH Fuse120oC
CONTROL, NO FUSERd6G Loaded (PSS/PAH)6 Capsules
Many Challenges Processing Delicate Capsules
pH pH Fuse120oC
(PSS/PAH)9 loaded and fused capsules
CONTROL, NO FUSERd6G Loaded (PSS/PAH)6 Capsules
Problematic Results: Collapsed Capsules, Agglomerates, Dye unloading, Low Yields…
Plan B: Patched Capsules Formed Around Solid Cores
BREAKTHROUGH: Functionalize and fuse with core intact
Masking Substrate Masking Substrate Masking Substrate
Uniform Fine and Coarse Coatings Created
(a)(a)
5μm
(b)
5μm
(b)
60 nm FYG 190 nm FYG
4 gL aR
Microcapsules Swell and Shrink After Fusing Still pH responsive after heat treatment Patch and shell completely intact Survive pH range 1 - 12
5μm
(a) (b)
5μm
(a) (b)
pH 2.5 pH 5
10 % reduction in capsule diameter
Microcapsules Retain Dye after Loading
Incubate with Rd6G, a cationic low MW dye
Loading
Overlay
Dried and Collapsed Lithographed Capsules Rehydrate
Bare Capsules ControlLithographed Capsules
(f)(a) (b) (c)5 µm (f)(a) (b) (c)5 µm (d) (e) (f)(d) (e) (f)
Dried 20 min 35 min Dried 25 min 120 min
H2O H2O
Spherical Morphology Restored Still Collapsed and Adhered to Substrate