CAREER: Strong Responses in Weak Systems -- Movement of Soft Polymeric Nanoparticles through Confining Nanopores

Case Western Reserve University, Cleveland OH

Investigators

Abstract

NON-TECHNICAL SUMMARY This CAREER project focuses on developing an understanding of the fundamental science behind the movement of soft polymeric particles through pores at the nanoscale level (called translocation). Such movement is fundamental to many processes in nature, and has far-reaching impacts and applications -- whether it pertains e.g. to viral infection of crops leading to food shortages and starvation, or to purification of water using porous membranes. This research specifically focuses on studying new and unique effects that occur when polymers are attached to the surface of a particle, and investigates how these effects can be used to create new types of particles that favor translocation over other particles of similar sizes. Measurements of these new particles will help in the development of a theory for soft particle translocation and broaden the range of applications. The complementary education and outreach activities will result in the development and use of the Microsoft HoloLens for polymer education, a new course in polymer modeling and visualization, the training of a total of 10 high school students, and the training of approximately 100 middle school teachers in inquiry-based education as part of the Next Generation Science Standards in the United States. Looking to the future, the proposed research, education, and outreach activities will be relevant and influential to vital areas of society such as efficient water purification and food-source security. TECHNICAL SUMMARY The PI will investigate the impact of cononsolvency and n-clustering on the transport of polymeric nanoparticles through a single, strongly confining nanopore. Cononsolvency and n-clustering are solution phenomena in which polymers collapse and aggregate despite the presence of very favorable interactions between the polymers and solvent. If understood and purposefully manipulated, these unique behaviors can yield soft materials that mimic biological systems and behave in "strong ways" -- such as particles that respond to weak stimuli to undergo substantial structural rearrangement to traverse a pore. These behaviors will lead to simple mechanisms for controlling the flow of soft particles using only weak stimuli. The primary objectives of this project are to: 1) Synthesize new classes of nanoparticles that exploit n-clustering and cononsolvency of poly(N-isopropylacrylamide) to respond favorably to geometrical confinement. 2) Investigate and develop a comprehensive theory of the translocation of soft particles through bare pores using an integrated computational and experimental approach. 3) Employ big-data analytics to quantitatively verify our hypotheses and extract additional hidden relationships between variables. 4) Transform polymer education with interactive visualization techniques using both the Microsoft HoloLens and 3D printing technologies to engage and motivate university students, K-12 educators, and others in scientific exploration. Molecular/particle movement will be monitored with ionic current measurements on a solution cell, nanoparticle characteristics will be determined by light scattering, neutron scattering, and electron microscopy. Dissipative particle dynamics (DPD) will be used to model nanoparticle traversal.