School of Chemical Engineering
Purdue University

Precise and economical fabrication of complex functional structures at nanometer and micrometer scales presents an essential opportunity for many advanced technologies and related sciences.  Our overall research goal is to extend the knowledge and methodology in the studies of polymer and colloid self-assembly to help solve problems in these technologically demanding areas.  Our current research focuses on the fundamental issues surrounding the use of novel polymer and colloid-based building blocks and processing techniques to develop new self-assembled materials which can address grand materials challenges faced in various frontier research areas.  Below are brief descriptions of some of our current research projects.  The names of the graduate investigators associated with individual projects are given in the parenthesis:

• "Laterally-Mobile Mixed Polyelectrolyte/Polymer Brushes" (Kevin N. Witte)

  

Understanding the behavior of polymers end-grafted to a surface is fundamental to many technological applications of polymers, including colloidal stabilization, membrane surface modification, ion-exchange adsorbents, lubricative coating, and the creation of surfaces with externally tunable properties.  In this project, using a combined theoretical and experimental approach, we investigate novel mixed polymer brush systems, namely, the mixed brushes composed of laterally-mobile polyelectrolyte and non-charged polymer chains.  This novel mixed brush system offers previously unavailable opportunities (i) to produce mesoscopic surface patterns of various length scales by long-range-frustrated lateral phase separation between the two chain types and (ii) to create functional interfaces with surface properties switchable between charged and non-charged states. 

• "Multicomponent Polymer/Micelle-Based Gene Delivery" (Rahul Sharma, Dana J. Gary)

Gene therapy holds great promise as a treatment for genetic diseases such as cystic fibrosis, sickle cell anemia, and Huntingtons disease.  However, a method for safe and efficient in vivo gene delivery into the targeted cells is presently a major limiting factor.  Our interdisciplinary collaborative research efforts currently explore new approaches for improving in vivo DNA/siRNA delivery using two new classes of polymeric materials: (i) triblock copolymer micelle nanoparticles, and (ii) intracellularly degradable polycations. 

• "Guided Assembly of Colloids at Solid-Liquid and Liquid-Gas Interfaces" (Jaehyun Hur)

High-quality two-dimensional (2D) colloid crystals have potential utility in many technological applications, for instance, as surface templates for epitaxially growing 3D colloid photonic crystals, as structural elements for modulating the surface plasmon properties of materials, and as mold structures for fabricating microlens.  Therefore, precise and economical fabrication of 2D colloid crystals presents essential opportunities for advancement of these technologies.  In this project, we explore a new method of fabricating highly-ordered 2D colloid crystals with non-closed-packed symmetries with unprecedented efficiency and precision.