(86g) Pattern Formation of Amphiphilic Particles and Polymers Under 2D Confinement

In nature, quasi-ordered nanostructures yield structural color in many species such as Male Eastern Bluebirds⁽¹⁾, the Hawaiian Bobtail Squid⁽²⁾, and Blue Spikemoss⁽³⁾. Assemblies with this kind of precise meso-structure are difficult to replicate in the laboratory, and our work attempts to engineer quasi-ordered nanostructures in a scalable manner using two components: (1) an amphiphilic polymer and (2) amphiphilic particles under 2D confinement.

We have examined the behavior of the first component, amphiphilic polymers, at the air-water interface and found our rationally-designed amphiphilic polypeptides self-assemble under confinement in a manner that could be useful for serving as an organic template capable of rearrangement ⁽⁴⁾. Additionally, we have examined the behavior of the second component, dichlorodimethyl silane surface-modified silica particles and Janus particles, revealing packing behavior at the air-water interface that includes buckling, folding and subduction.

This work investigates the combination of the amphiphilic polypeptide and Janus particle assembly and the possibility for it to lead to structural color. Our studies highlights the non-equilibrium behavior of anisotropic particles coupled to amphiphilic co-polymers such as pluronic, which have also demonstrated unique conformational changes under compression and are well documented in the literature. Combination of the particle systems with pluronic provides control over the spacing and patterning of the particle layers. Using a Langmuir trough, surface pressure isotherms of mixed particle-pluronic systems are obtained, revealing composite-like behavior at the interface. Additionally, Brewster angle microscopy is used to observe the phase behavior of the two-component systems under compression and expansion. Current experiments investigate these mixed systems under varying compression rates.

Works Cited:

1. Dufresne, E.R.; Noh, H.; Saranathan, V.; Mochrie, S. G. J.; Cao, H.; Prum R. O. Self-Assembly of amorphous biophotonic nanostructures by phase separation, Soft Matter 2009, 5, 1792-1795.
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3. Vukusic, P.; Sambles, J. R. Photonic structures in biology, Nature 2004, 429, 680-680.
4. Leon, L.; LoGrippo, P.; Tu, R. Self-Assembly of Rationally Designed Peptides Under 2-D confinement, Biophys. J. 2010, 99.