Harnessing the power of polymer phase interactions in the design of supramolecular interpenetrating networks

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NON-TECHNICAL SUMMARY:Biological materials often feature complex assemblies that utilize the interaction between phases possessing disparate mechanical properties to achieve synergistic and highly tunable effects. Incorporation of this nature-inspired structural interplay into synthetic polymeric systems is proposed toward the development of mechanically-robust and functional materials. Their structures and properties will be studied and correlated in this project using a combination of advanced instrumentation. The ability to control and tune the molecular and materials architecture in complex systems addresses key scientific challenges related to mechanically adaptive behavior and controlled transport in new materials development. Such systems have potential use in a range of applications, including biomedical delivery vehicles, sensors, actuators, and membranes, and may potentially also offer advantages in terms of processability. Graduate and undergraduate students will gain exposure to cross-cutting research -- from synthesis to processing -- and utilize these advances in the areas of mentorship and community outreach. A mentoring platform for female students and post-docs, particularly from underrepresented groups, to engage in dialogue regarding shared experiences and career pathways will be supported. An expanded partnership with a K-12 all-female independent school will provide hands-on demonstrations, career development, and safety/ethics training during a two-week science/engineering exposure program for high-school girls. TECHNICAL SUMMARY:Supramolecular associations have been widely explored in elastomers, blends, and copolymer systems, and have motivated interest in the utilization of dynamic associations in the design of interpenetrating polymer networks (IPNs). IPNs provide a robust platform to explore the role of supramolecular motifs as a toughening mechanism due to the intimate interaction of the polymer phases. This research program will elucidate structural parameters and guiding principles to direct fabrication of supramolecular IPNs with tunable interfacial interactions, tailored structural heterogeneity, and synergistic mechanical behavior. Three classes of supramolecular IPNs will be explored that utilize: (1) complementary and orthogonal supramolecular associations with focus on how motifs of varying interaction strength/organization influence microstructure development and dynamics, (2) self-complementary and complementary hydrogen bonding associations with an emphasis on the correlation between the resulting IPN morphology, mechanics, and supramolecular response, and (3) particulate-reinforcement as an approach to control phase coarsening, mechanical behavior, and functionality. A full suite of structural, thermal, mechanical, and morphological characterization techniques will be utilized, including variable temperature nuclear magnetic resonance, fluorescence spectroscopy, tensile testing, dynamic mechanical analysis, atomic force microscopy, rheology, scanning electron microscopy, and X-ray and neutron scattering.