(4ak) Adaptable Polymer Networks with Enabling Properties

Prior Research: My research has resulted in 28 (first and co-author) publications with over 1300 citations (Google scholar). In addition, I have aided in writing 5 successfully funded research proposals including an NSF GRFP and an NSF I-Corps grant for business and research plan discovery. My research has focused on implementing interesting chemistries and physics into crosslinked polymer networks for a diverse array of applications in both academic and commercial sectors. I completed my PhD in Chemical Engineering under Dr. Christopher Bowman at CU Boulder with a brief stent as a visiting scholar in the lab of Dr. DJ Broer at the Technical University of Eindhoven. For my post-doctoral studies, I joined the lab of Dr. Ryan Hayward at UMass Amherst, later relocating to CU Boulder. Through this work, I have developed a diverse scientific skill set by experience in photopolymerization, organic synthesis, polymer physics, polymer chemistry, material science, mechanical property characterization, AC impendence, liquid crystals, polymer optics, and additive manufacturing.

Research Philosophy: The future of soft robotics, energy infrastructure, and next-generation devices will require materials with special optical, electronic, and mechanical properties. To this end, my research interests are driven by the translation of unique chemistries and physical phenomena into polymeric materials that are readily accessible and meet the needs of an ever-changing technological environment. Collaboration and creativity are a cornerstone of my research philosophy and believe the best work is done in an open and diverse collaborative setting. I aim to leverage my expertise at the interface of chemistry, physics, and polymer science to develop platforms to advance our understanding in the following areas:

Proposed Research areas:

Covalent Adaptable Networks (CANs): CANs are polymer networks with dynamic covalent bonds installed on the polymer backbone. Once activated with light, heat, or catalyst, the dynamic bond exchange causes the otherwise static polymer network to behave liquid-like and provides a switch to turn the network from a solid to liquid (or vice versa). The tunable liquid/solid like behavior is engineered through choice of exchangeable bond, network topology, and responsive stimulus. Consequentially, when an external force (e.g., mechanical) is applied, the network will behave as a solid when the reaction is turned off and a liquid when the reaction is turned on. Thus, the material’s response to any given force can be controlled through reaction engineering. While most research in the field employs mechanical and osmotic forces to perturb the network, I aim to expand the scope to electric fields where the capacitance and charge carrier mechanisms are highly dependent on the diffusion and relaxation within the polymer network or polymer liquid. This work will contribute to the fundamental knowledge surrounding CANs and develop novel techniques to create soft materials with permanent dipoles for energy harvesting devices and sensors.

Soft Polymers for Electronic Devices: Soft materials are quickly becoming an integral part of modern electronics by the development and application of soft robotics, electronic skin, next generation batteries, and human-machine interfaces. Dielectric elastomers are one class of electroactive, shape shifting materials that rely on a soft dielectric layer which is set between compliant electrodes. Once a voltage (kV-MV generally) is applied, the soft layer is compressed, thereby deforming the (elastomer, device, something descriptive here) in plane. While these soft actuators are promising for a variety of applications, broad adoption will require lower voltages and more compact designs. I aim to engineer dielectric layers with spatially patterned modulus and dielectric constant to direct and amplify actuation. The impact of this work will increase the design space available to practitioners in order to reduce the actuation voltage and efficiently convert electrical energy to mechanical energy.

Recyclable Polymers: CANs are viewed as a potential solution to plastic waste because they have intrinsically degradable crosslinks making depolymerization and reuse straightforward. To this end, thermally activated chemistries are most frequently applied, however, this presents stability issues during the material use lifetime. Part of my research thrust will be to explore electrically stimulated activation of CANs which provide another route to remold and depolymerize crosslink networks under mild conditions.

Teaching Interests

I can teach the core curriculum of Chemical Engineering particularly reaction kinetics, separations, thermodynamics, transport, introductory courses, and organic chemistry related courses. In addition, I have experience in polymer science and engineering. I have mentored over 15 younger undergraduate and graduate students from a diverse array of backgrounds in various research settings. I have mentored multiple undergraduate students who were able to present research at a university-wide or national conferences with 3 being included as authors on published manuscripts.

Class Experience:

General Chemistry for Engineers, TA: I supervised a lab section of 20 freshman student where I was tasked with giving practice problems and helping the students complete the lab.

Reaction Kinetics, TA: I was the lead TA for a 150-person, Junior level course. I gave a weekly recitation and hosted office hours. Additionally, I prepared and delivered a series of lectures on reaction hazard safety.

Selected Publications:

1. McBride, M. K.; Martinez, A. M.; Cox, L.; Alim, M.; Childress, K.; Beiswinger, M.; Podgorski, M.; Worrell, B. T.; Killgore, J.; Bowman, C. N., A readily programmable, fully reversible shape-switching material. Adv. 2018, 4 (8).
2. Worrell, B. T.; McBride, M. K.; Lyon, G. B.; Cox, L. M.; Wang, C.; Mavila, S.; Lim, C.-H.; Coley, H. M.; Musgrave, C. B.; Ding, Y.; Bowman, C. N., Bistable and photoswitchable states of matter. Commun. 2018, 9.
3. McBride, M. K.; Hendrikx, M.; Liu, D.; Worrell, B. T.; Broer, D. J.; Bowman, C. N., Photoinduced Plasticity in Cross-Linked Liquid Crystalline Adv. Mater. 2017, 29 (17).
4. Nair, D. P.; Cramer, N. B.; Gaipa, J. C.; McBride, M. K.; Matherly, E. M.; McLeod, R. R.; Shandas, R.; Bowman, C. N., Two-Stage Reactive Polymer Network Forming Systems. Funct. Mater. 2012, 22 (7), 1502-1510.