Synthetic Biology

My research program meets the ever-present challenge in the field of materials engineering to identify innovative methods for producing materials that address a complex performance profile. I use polymers as the platform from which I build functional materials, and my research aims to have full design authority over their ultimate chemistry and structure so that I can engineer several desired properties including flexibility, mechanical robustness, wettability, biocompatibility, response to external stimuli, etc. To enable this design, I study the fundamental driving forces that dictate polymer architecture, conformation, heterogeneity, and micro-structure during formation. The over-arching goal of my program is to use fundamental studies to identify versatile and improved methods towards material designs.

Heterogeneous polymer materials, such as blends or composites are often used to address the need for bulk performance or properties that cannot be achieved using a single monomer building block. To address the need for more efficient techniques to create heterogeneous materials, my graduate research studied the dynamic process of in situ phase separation during the formation of polymer networks. Specifically, I demonstrated that by understanding the simultaneous yet non-equivalent changes in thermodynamics and kinetics during photopolymerization, it is possible to form well-structured, heterogeneous materials with broad differentials in local properties despite rapid network formation. Furthermore, with this approach I synthesized network materials with utility and performance superior to their homogeneous, non-structured analogues. I also developed polymerization protocols that simultaneously conformed to processing constraints, yet also optimized heterogeneous phase structure in order to attain target property profiles. An example of this work being the demonstration of significant interfacial stress reduction in phase separated acrylic networks (a class of materials that are often employed as dental restoratives, which typically fail due to polymerization stress) based on heterogeneous phase structure and the rate of network formation.

Interfacial materials represent another class of complex materials, as for many critical surface properties (wettability, adhesion, etc.) both the surface chemistry and three-dimensional topography play an important role. In my post-doctoral research, both at the Université de Nice (Nice, France) and currently at Northwestern University, I have developed bio-inspired, structured interfaces using polymerization techniques. I synthesized thiophene-based monomers and studied the effects of variations in structure and polymerization protocol on the resultant in situ surface polymerization of these moieties via electrochemical deposition. With these studies, I created interfaces with robust features such as spherical agglomerates, nano-folds, and nano-tubes which all formed in situ and without any templating. I have also explored the use of heterogeneous photopolymerizations as an approach to tune surface structure and chemistry for interfacial materials. Using my expertise in heterogeneous network polymerizations, I developed coating materials where the formation of topographical surface features was driven by local differentials in polymerization stress. These studies have resulted in the rapid fabrication of interfaces with desirable properties such as superhydrophobicity and strong adhesion. My continued work on this topic explores the influence of polymer chemistry, structure, and architecture on interfacial properties when developing coating materials.

Future research directions:

My independent career research will combine my skills to develop advanced materials addressing needs from varied fields including: coatings, adhesives, and biomaterials. Initial work in the Szczepanski group will address three specific aims: (1) manipulating heterogeneous network structure as a means to prevent hydrolytic degradation in aqueous environments, (2) engineering of biomimetic interfaces with controlled functionality, (3) incorporation of stimuli-responsive moieties in polymer coating materials to create robust, switchable interfaces.

Selected Publications (15 total, 10 first author)

1. C.R. Szczepanski*, T. Darmanin, G. Godeau, F. Guittard “Template-less Patterning of Polymeric Interfaces for Controlled Wettability via in situ Heterogeneous Photopolymerizations” Macromol. Chem. Phys.2018. *corresponding author
2. C.R. Szczepanski, I. M’Jid, T. Darmanin, G. Godeau, F. Guittard “A template-free approach to nanotube-decorated polymer surfaces using 3,4-phenylenedioxythiophene (PhEDOT) monomers.” J. Mater. Chem. A 2016, 4, 17308-17323
3. C.R. Szczepanski, T. Darmanin, F. Guittard “Spontaneous, Phase-Separation Induced Surface Roughness: A Novel Method to Design Parahydrophobic Polymer Coatings with Rose petal-like morphology.” ACS Appl. Mater. Interf. 2016, 8, 3063-3071.
4. C.R. Szczepanski, J.W. Stansbury “Modification of linear prepolymers to tailor heterogeneous network formation through photo-initiated polymerization-induced phase separation.” Polymer 2015, 70, 8-18.
5. C.R. Szczepanski, J.W. Stansbury JW. “Stress reduction in phase-separated, cross-linked networks: influence of phase structure and kinetics of reaction.” J. Appl. Polym. Sci. 2014, 131, 40879.
6. C.R. Szczepanski, C.S. Pfeifer, J.W. Stansbury “A new approach to network heterogeneity: Polymerization Induced Phase Separation in photo-initiated, free-radical methacrylic systems” Polymer 2012, 53, 4694-4701.

Teaching Interests:

When educating and training the future generation of engineers, it is crucial to emphasize that each course is not designed solely to introduce a narrowly focused set of analytical skills, but also to improve a student’s overall aptitude at solving complex problems that draw on a variety of subject matters. The fundamental core subjects of chemical engineering are not topics that exist in isolated circumstances but must be called upon throughout one’s professional career. I have established a teaching philosophy that is centered around three essential goals for my students: (1) that they successfully acquire a new set of skills to add to their engineering toolbox, (2) that they gain an understanding as to how the techniques they learn can be applied to a variety of problems especially outside the context of class, and (3) that they improve their overall problem-solving approach during the course. To ensure that these goals are being met, I organize my lectures such that both the student’s comprehension and my own teaching are being assessed throughout the course, using active learning techniques to engage all students.

Up to this point in my career, my teaching appointments have been diverse in that I have worked with students at various stages of their educational careers, giving me valuable insight as to how to best engage students based on their educational experiences. As a graduate teaching assistant at the University of Colorado, I taught laboratory sections and developed recitation materials for General Chemistry (first year undergraduates, 2010) and Process Controls (fourth year undergraduates, 2012). In 2014 I was a Teaching Fellow for my graduate department, where my responsibilities included preparing course materials for 10 independent General Chemistry lectures. In my current role at Northwestern, I have been a guest lecture for an introductory polymers course, which consists of upper level undergraduate as well as graduate students. Beyond these classroom experiences, I also served as the Lead Graduate Teacher for my graduate department for one academic year, during which I was responsible for training graduate students in engineering pedagogy and effective teaching techniques. Because of my interest on developing and improving problem-solving approaches, I am most interested in teaching foundational Chemical Engineering courses such as: Material & Energy Balances, Thermodynamics, and Transport Phenomena. Given my research expertise I would also be interested in developing and teaching courses related to polymer science, polymer engineering, photopolymerizations, materials characterization techniques, as well as bio-inspired approaches to materials engineering.