Laura Bradley, assistant professor of polymer science and engineering, recently was awarded a five-year, $500,000 Faculty Early Career Development (CAREER) Program grant by the National Science Foundation (NSF) that will support her research on producing soft materials with ordered and oriented architectures for advanced applications in membranes and surface coatings.
Soft materials such as liquids, polymers, foams, gels and colloids can be shaped and re-shaped for use in a variety of applications, says Bradley, such as membranes with pores that are vertically oriented, which increases permeability while maintaining selectivity, or what’s allowed to pass and what is not. Commercial membranes currently suffer from low pore densities and high cost, she adds. Her future projects will study the production of scaffolds for biomedical applications such as tissue engineering.
The Bradley lab uses chemical vapor deposition to control the accumulation of polymers at interfaces; when performed on liquid surfaces in situ, mechanisms of diffusion and aggregation drive the assembly. As she explains, “Controlling the sequential addition of materials to the liquid surface enables us to control the final self-assembled morphology in a continuous process to achieve targeted architectures ranging from nanoparticles to porous composites.”
Her approach is inspired by nature’s ability to take advantage of transport mechanisms to construct cell components. She explains, “Scientists are constantly trying to mimic assembly mechanisms found in nature. Controlling material transport and understanding competitive time scales of assembly and transport mechanisms will open opportunities in new methods for materials production.”
She adds, “The process unfolds in a more dynamic way on the liquid surface, which allows you to manipulate assembly. If you control the feed and rate of delivery, over time you can control the properties of a material as you make it.”
The specific vapor-phase deposition technique the Bradley group employs is called “initiated chemical vapor deposition” or “iCVD,” which produces a wide range of functional polymers incorporating hydrophobic, hydrophilic, biocomptable or stimuli-responsive properties. Work from Bradley’s Ph.D. dissertation showed that polymer growth on liquids by iCVD is not uniform across the surface.
Over the next five years with NSF support, she will add new assembly mechanisms exploiting nematic – oriented – liquid crystals as the liquid substrate to organize the growth of polymers and produce uniform materials such as monodisperse nanoparticles or membranes with constant pore size and shape.
Bradley says, “In this project, we will leverage UMass Amherst strengths in polymer science and condensed matter physics. The campus’s collaborative atmosphere makes it a great place to carry out interdisciplinary research. Receiving the NSF CAREER grant is especially motivating to our new reseach group. I have the pleasure of working with creative and enthusiastic students. As a team, we are excited about our new research directions and the support from NSF.”