The PI proposes to create stimulus-responsive interfacial microstructures and microdevices through the photodirected assembly of polyelectrolytes. Recent advances in chemical product design, medicine and nanotechnology have ushered in a new age of ?smart? materials that respond to external stimuli such as changes in pH, ionic strength, temperature, and mechanical or electromagnetic perturbations. Stimulus-responsive polyelectrolyte complexes are routinely used as building blocks for these materials and find countless applications, ranging from controlled release of bioactive payloads, to self-healing materials and soft microelectromechanical systems (MEMS), to energy devices and water purification. These technologies require custom-designed structures with an assortment of well-defined morphologies. Yet, methods for the microfabrication of polyelectrolyte complexes remain limited to simplistic structural motifs (e.g., planar, spherical, cylindrical, and prism-like or pyramid-like). This severely limits both the range and intricacy of the supramolecular architectures that can be prepared from polyelectrolytes, and presents a major obstacle in the 3-D assembly of polyelectrolyte-based microdevices.
To address this, the PI aims to direct the assembly of intricate polyelectrolyte structures via 3-D photopatterning of polyelectrolyte solutions, where one of the polymer species only becomes charged when exposed to light. The PI hypothesizes that the irradiation at the focal point of the multiphoton laser will induce rapid and localized polyelectrolyte self-assembly into colloidal materials, whose shapes and dimensions will be directed by the beam path. This project has three objectives: (1) investigating photodirected assembly of polyelectrolytes as a method for preparing intricate supramolecular structures, (2) dissecting the photodirected assembly process with the view of developing robust guidelines for controlling materials interfacial structure and stimulus sensitivity, and (3) exploiting the stimulus-responsive properties of photopatterned polyelectrolyte complexes to prepare micron-scale controlled release devices, actuators and materials that self-destruct. This research leverages the PI?s background in polyelectrolyte self-assembly, and will dramatically expand the range and intricacy of polyelectrolyte-based materials that can be prepared for customized controlled release, sensor and actuator technologies.
Broader Impacts:
This work will advance the design and microfabrication of smart devices for medical, environmental and household applications. Likewise, the ability to produce novel stimulus-responsive structures has the potential to accelerate the development of advanced membranes, coatings, electronics and energy devices. Importantly, this research will be closely integrated with educational outreach. The PI will introduce high school students to stimulus-responsive polyelectrolytes in the Engineer for a Day and EXCEL programs that are offered to Toledo Public Schools. Moreover, he will continue his involvement in the Engineering for Teachers of Migrant Students (ETMS) distance learning course. ETMS provides graduate training for teachers in rural communities who teach children of migrant farm workers, and aims to develop a set of experiments that demonstrate the importance of mathematics, science and engineering to everyday life. The PI has recently become involved with ETMS, and has already developed several demonstrations that use stimulus-responsive polymers found in household products (e.g., alginate, poly(acrylic acid), and methylcellulose) to reinforce concepts that are learned in high school chemistry. To disseminate the ETMS materials more broadly, step-by-step tutorials will be posted on the PI?s website and on YouTube. These outreach activities will help increase and diversify the enrollment of science and engineering students. Furthermore, the PI?s research will train undergraduate and graduate students (including women and underrepresented minorities) in the use of materials characterization techniques, and in the fundamentals of colloid and polymer science. This research will also generate stimulating examples and project topics, which the PI will incorporate into the colloids and transport phenomena courses that he will teach at the University of Toledo.
