Prof. Andrew Lyon, Georgia Tech

Smoothing Out the Defects with Polymer Microspheres

This talk will discuss various aspects of the defect tolerance, self-healing, and geometry adaptation properties of hydrogel microspheres. Hydrogel microspheres (microgels) are micron- to submicron-sized particles, each composed of a cross-linked network of water soluble polymer. As a result of their large water content, which can easily exceed 99% by volume, microgels composed of flexible polymers such as poly(alkylacrylamides) have a high degree of conformational flexibility; they are exceedingly soft structures. We have found that this softness permits microgels to be extremely adaptive to geometric restrictions, resulting in defect-tolerant colloidal crystals where large "dopant" particles are assimilated into the lattice seamlessly. This adaptive nature is also illustrated by the passage of microgels through orifices at least 10-fold smaller than the equilibrium microgel diameter, which is potentially relevant in the use of microgels for injectable drug delivery formulations. Finally, the use of microgels in self-healing polymer films will be discussed, along with illustrations of the applicability of such films in reconstructive surgery.