Meso-PolymersJoseph M. DeSimone, University of North Carolina at Chapel Hill, DMR 0923604

The use of the high resolution molding technique referred to as Particle Replication in Non-wetting Templates (PRINT®) allows for the fabrication of nanoparticles with novel shapes, including those with high aspect ratios. Recently triblock filamentous nanoparticles were fabricated containing a hydrophilic center and hydrophobic end segments. Under certain conditions self-assembly of these particles was observed in an aqueous environment, yielding novel architectures, some of which resemble micelle-like structures. These mesoscopic analogues of synthetic polymers represent a new class of nanoparticles with the potential to undergo self-assembly in a controlled manner. Chemical composition also plays a significant role in the properties of filamentous nanoparticles, affecting mechanical properties such as modulus. As observed by SEM 80x5000nm particles fabricated with hydrophilic PEGDA are quite flexible, while particles fabricated with hydrophobic PEGTA are highly rigid.

(A) Fluorescence microscope images of 80x5000nm filamentous particles with hydrophobic tails (red) and a hydrophilic center (green). (B) Self-assembly of three triblock filamentous particles. Inset: SEM of array of 80x5000nm particles. (C) SEM of flexible hydrophilic PEGDA 80x5000nm particles. (D) SEM of rigid hydrophobic PEGTA 80x5000nm particles.

Meso-PolymersJoseph M. DeSimone, University of North Carolina at Chapel Hill, DMR 0923604

We demonstrated a novel strategy to generate a range of monodisperse amphiphilic rod-like particles with tunable dimensions and chemical composition of the blocks. Directed self-assembly of these anisotropic amphiphilic block particles at the water/oil interface illuminates the relationship between particle architecture and self-assembly behavior. The amphiphilic triblock rods self-assembled into ribbons while amphiphilic diblock rods formed a bilayer structure. This new family of anisotropic block rods provides a platform for theoretical as well as experimental understanding of self-assembly behavior of anisotropic nonspherical particles. The concept of multiphases coexisting in a particle is anticipated to open an avenue to design new drug carriers, allowing the encapsulation of several drugs with hydrophilic or hydrophobic properties in one carrier. In addition, the creation of block features paves the way for fabricating micro-electronics.

Dr. DeSimone believes that “diversity is the key to innovation” and following that directive he has assembled a group of researchers that includes 15 women and representatives from five nations outside the US (India, Iran, China, Canada, and Israel).