Biosketch

Dr. Christian Pester received his Diploma in Polymer and Colloid Chemistry from the University of Bayreuth (Germany). In 2013, he received his doctorate from RWTH Aachen (Germany) working for Prof. Dr. Alexander Böker at the DWI – Leibniz Institute for Interactive Materials (Germany). He graduated summa cum laude and was awarded the Borcher’s Medal for his dissertation on “Block Copolymers in Electric Fields”. Dr. Pester was then awarded an Alexander-von-Humboldt Feodor-Lynen Postdoctoral fellowship to work with Profs. Edward J. Kramer and Craig J. Hawker at the University of California, Santa Barbara (USA). Dr. Pester began his independent academic career at the Pennsylvania State University, where he became the Thomas K. Hepler Early Career Professor in Chemical Engineering. He was tenured and promoted to Associate Professor of Chemical Engineering in 2023 with courtesy appointments in the Chemistry Department and the Materials Science and Engineering Department. In 2024, Dr. Pester joined the University of Delaware as an Associate Professor in the Materials Science and Engineering Department. He also was awarded a Humboldt-Fellowship to study mental health of graduate students as a visiting researcher at TU Braunschweig (Germany) and the Leibniz Institute of Resilience Research in Mainz (Germany).

Awards

• TOSOH Award for Excellence in Polymer Science (2024)
• ACS Polymers Au: Rising Star (2023)
• RSC Journal of Materials Chemistry A: Emerging Investigator (2023)
• IUPAC Young Observer (2023)
• ACS PMSE Young Investigator (2022)
• NSF CAREER Award (2022)
• IUPAC Young Observer (2021)
• Thomas K. Hepler Early Career Professorship in Chemical Engineering (Penn State University, 2020)
• ACS PRF Doctoral New Investigator Award (2019)
• Borchers Medal in recognition of outstanding Ph.D. thesis (summa cum laude, RWTH Aachen University, 2014)

Research Interests

Engineering of Advanced Functional Surfaces

The covalent attachment of polymers has emerged as a powerful strategy for the preparation of multi-functional surfaces. Patterned, surface-grafted polymer brushes provide spatial control over a variety of physical properties and allow for fabrication of ‘intelligent’ substrates which selectively adapt to their environment. Recent advances in our group have enabled the use of photolithography to produce functional and chemically-patterned surfaces via surface-initiated (SI) photoinduced electron/energy transfer (PET) reversible addition–fragmentation chain transfer (RAFT) polymerization. Oxygen tolerance, mild reaction conditions, and the use of visible light make this approach user-friendly for the design of e.g., anti-microbial surfaces, anti-fogging coatings, organic light emitting diodes (OLEDs), and various other functional coatings.

1. W. Pester*, H.-A. Klok*, and E. M. Benetti*. Opportunities, Challenges and Pitfalls in Making, Characterizing and Understanding Polymer Brushes. Macromolecules 2023, 56, 9915.
2. Fromel, D. Sweeder, S. Jang, T. A. Williams, S. H. Kim, and C. W. Pester*. Superhydrophilic Polymer Brushes with High Durability and Anti-Fogging Activity. ACS Appl. Polym. Mater. 2021, 3, 5291.
3. Poisson, A. M. Polgar, M. Fromel, C. W. Pester*, and Z. M. Hudson*. Preparation of Patterned and Multilayer Thin Films for Organic Electronics via Oxygen-Tolerant SI-PET-RAFT. Angew. Chem. Int. Ed. 2021, 60, 19988.
4. Li, M. Fromel, D. Ranaweera, S. Rocha, C. Boyer*, and C. W. Pester*. SI-PET-RAFT: Surface-Initiated Photoinduced Electron Transfer-Reversible Addition–Fragmentation Chain Transfer Polymerization. ACS Macro Lett. 2019, 8, 374.

Heterogeneous Photocatalysis

Photocatalysis is a potent approach that provides user-friendly access to small and macromolecular molecules under mild reaction conditions and visible light irradiation. However, the photocatalysts’ inherent visible light absorption means that catalyst residuals in products can lead to discoloration and material degradation. The high cost of common photocatalysts also makes their use on large scales economically challenging. Our work on heterogeneous photocatalysts attempts to address these limitations. The materials we develop are potent catalysts for various photochemistries – from organic synthesis to photopolymerization to wastewater remediation.

1. Hunter, J. L. Sacco, K. Katterle, J. Kirigo, T. K. Wood, E. W. Gomez*, and C. W. Pester*. Photoactive polymer coatings for antibacterial applications. Eur. Polym. J. 2024, 213, 113090.
2. Bell, B. Hunter, M. Alvarez, S. D. K. Seera, Y. Guo, S. H. Kim, and C. W. Pester*. Hydrolysis-Resistant Heterogeneous Photocatalysts for PET-RAFT Polymerization in Aqueous Environments. J. Mater. Chem. A 2023, 11, 16616.
3. Bell, S. Freeburne, A. Wolford, and C. W. Pester*. Reusable Polymer Brush-Based Photocatalysts for PET-RAFT Polymerization. Polym. Chem. 2022. 13, 6120.

Self-healing Coatings

The incorporation of self-healing properties to repair scratches (or other minor damage) has revolutionized the coating industry by increasing service life, sustainability, and optical appearance. Our work addresses challenges with robustness of self-healing coatings through surface-tethered covalently adaptable networks. Surface-initiated polymerization is combined with a spray-coating approach to deposit polymers and provide reversible crosslinks with the tethered chains and the coating. Without this polymer brush primer layer, the coatings lack the ability to self-heal completely, are labile to solvent, and exhibit shear delamination upon scratching. The tethered coatings can autonomously self-heal micron-scale incisions within seconds at elevated temperatures.

1. Capets, S.F. Yost, B. D. Vogt*, and C. W. Pester*. Rapid self-healing of robust surface-tethered covalent adaptable coatings. Adv. Funct. Mater. 2024 (doi : 10.1002/adfm.202406277).

Hydrolysis of Post-consumer PET Plastic Waste

Municipal solid waste landfills in the United States are becoming increasingly burdened with plastics and textiles. This trend is anticipated to escalate, driven in part by the growing presence of polyethylene terephthalate (PET) in consumer products, such as beverage bottles and fast fashion items. In an NSF-funded collaboration with Prof. Phil Savage (Penn State), we are pursuing chemical recycling as a promising avenue for transforming PET waste back into its constituent monomers by investigating the potential of hydrolysis (isothermal or non-isothermal) to enhance the recovery of PET’s valuable monomer, terephthalic acid (TPA).

1. Pereira, W. Slear, A. Testa, K. Reasons, P. Guirguis, P. Savage*, and C. W. Pester*. Fast Hydrolysis for Chemical Recycling of PET. RSC Sustainability 2024, 2, 1508.
2. Pereira, P. Savage*, and C. W. Pester*. Acid Catalyst Screening for Hydrolysis of Post-consumer PET Waste and Exploration of Acidolysis. Green Chemistry 2024, 26, 1964.
3. P. Pereira, P. Savage*, and C. W. Pester*. Neutral Hydrolysis of Post-consumer Polyethylene Terephthalate Waste in Different Phases. ACS Sustainable Chem. Eng.  2023, 11, 7203.