MechE Final Oral Defense: Yuanzhi Li

TITLE: NANOSTRUCTURED GELS FROM CROSS-LINKED BLOCK COPOLYMERS FOR SELECTIVE INFUSION TEMPLATING

ABSTRACT: Gels made from polymer networks with spatially well-defined mesoscale periodicity of distinctive chemical domains offer the potential for directing nanoconfined material synthesis to fabricate complex material nano-architectures. While found in nature, such in-gel material synthesis and deposition remain underexplored in synthetic systems. This dissertation addresses this gap in knowledge with nanostructured gels from self-assembled and crosslinked block copolymers (BCPs) exhibiting two types of 3D bicontinuous gyroidal morphologies as well as one- and two-dimensionally ordered mesostructures. Our rationally designed BCPs feature one selectively crosslinkable block enabling morphological fixation and structural integrity, as well as two tethered blocks allowing tailored liquid uptake. The macromolecular design supports swelling of the monolithic gels beyond 400 vol% in organic solvents while retaining the periodicity of the chemically distinct mesoscale domains. Additionally, we introduce post-crosslinking in-gel modification strategies that introduce hydrophilicity into the networks, producing analogs that swell strongly in aqueous media yet maintain the integrity of their ordered nano-morphology. These ordered gels are a novel class of solvent-laden bulk materials with chemically distinct nano-environments on a periodic mesoscale lattice, which can form a tailored soft chemical template for structured functional materials. We demonstrate their utilization for selective infusion templating with the nanoconfined synthesis of monolithic polymer and functional inorganic materials exhibiting ordered nanostructures and mesoporosity, respectively. Our nanostructured gels will facilitate the manufacturing of traditionally hard-to-template materials as periodically nanostructured monolithic metamaterials with broad tunability in their physico-chemical parameter space. Additionally, they present a platform for systematically studying nano-confined synthesis and molecular transport in gels with chemically distinct and tunable domains.

COMMITTEE: ADVISOR Professor Joerg Werner, ME/MSE; CHAIR Professor Sheryl Grace, ME; Professor Keith Brown, ME/MSE/Physics; Professor William Boley, ME/MSE; Professor Abigail Plummer, ME/MSE