Latest News

February 2021:
Congratulations to Greg for successfully defending his thesis!

December 2020:
The Epps group welcomes Garrett Bass and Zachary Hinton as new post-docs!

December 2020:
The Epps group welcomes Sampanna Mhatre and Allison Koopman as new graduate students!

August 2020:
Alice Amitrano's research focused on the plant-powered replacements for plastics was featured in the UDaily. Congratulations to Alice! Details can be found here.

July 2020:
Three postdoctoral positions are available immediately in Prof. Thomas Epps' group in the Chemical & Biomolecular Engineering Department at the University of Delaware (UD). More information can be found here.

March 2020:
Congratulations to Dr. Epps for being named among 7 prominent scientists whose work helps to push their disciplines forward, presented in ACS Publications in honor of Black History Month! Details can be found here.

February 2020:
The Epps group welcomes Manisha Ahir as a new post-doc!

February 2020:
Congratulations to Esther for being selected for the Chemical Biology Interface (CBI) fellowship!

January 2020:
Congratulations to Lignolix for receiving the EDGE grant from the State of Delaware! Details can be found here.

January 2020:
Congratulations to startup Lignolix, one of the winners of the UDel FastPass Competition! The team focuses on sustainably making materials from renewable biomass. Technically and UDaily.

December 2019:
The Epps group welcomes Mruthula Rammohan, Mengying (Sara) Yang and Maida Mahmood as new graduate students!

October 2019:
The Epps group welcomes Aynur Guliyeva as a new post-doc!

October 2019:
The Epps group welcomes Antigoni Konstantinou as a visiting researcher!

July 2019:
The Epps group welcomes Craig Machado as a new post-doc!

June 2019:
Congratulations to Melody for successfully defending her thesis!

March 2019:
Congratulations to Melody for being selected as a finalist for the APS Division of Polymer Physics Frank J. Padden Jr. Award! A College of Engineering article can be found here.

November 2018:
The Epps group's work on tapered block polymer electrolytes is highlighted in UDaily, the Council of Graduate Schools, and Delaware NPR

November 2018:
The Epps group's work on turning waste lignin into tapes is highlighted by the U.S. DOE Office of Science

November 2018:
The Epps group welcomes Jordan Willie, Dajeong Kim, and Jignesh Mahajan as new graduate students!

October 2018:
The Epps group welcomes Chao Wang as a new post-doc!

October 2018:
The 2018 Future Faculty Workshop is featured in UDaily

August 2018:
Congratulations to Esther and Robert for passing quals!

July 2018:
The Epps group welcomes Eric Gottlieb as a new post-doc!

July 2018:
Seeking candidates for a post-doctoral position. Details can be found here

July 2018:
UD hosts the 2018 Future Faculty Workshop

June 2018:
Congratulations to Dr. Epps for being named a Fellow of the Royal Society of Chemistry!

June 2018:
The Epps group's work on biobased pressure sensitive adhesives is featured in UDaily

April 2018:
Announcing the 2018 Future Faculty Workshop to be held at UD

April 2018:
Congratulations to Melody for being named the Fraser and Shirley Russell Teaching Fellow in Chemical Engineering!

March 2018:
Congrats to Seung for a recent publication in Science!

March 2018:
The Epps group welcomes Silvia Grama as a new post-doc!

January 2018:
The Epps group is looking to hire two new post-docs, check out the postings here for more details

January 2018:
Congrats to Greg for passing quals!

November 2017:
The Epps group welcomes Esther and Robert as new grad students!

November 2017:
The Epps group welcomes Yi as a new grad student!

November 2017:
Congrats to Seung for receiving the Hanwha Award for Post Docs at AIChE!

November 2017:
Congrats to Victoria for receiving 1st-Place for her MESD Undergraduate Poster at AIChE!

October 2017:
Congrats to Dr. Epps for being elected as a 2017 Fellow of the American Physical Society

August 2017:
Morris et al. perspective is a top 20 read for August

August 2017:
Congrats to Priyanka for passing quals!

August 2017:
The Epps group welcomes Seung as a new post-doc!

July 2017:
Dr. Epps is appointed as the new CMET Director

June 2017:
The Epps group welcomes Shelby and Grace, as summer REU students!

May 2017:
Congratulations to Chad for successfully defending his thesis!

May 2017:
Congratulations to Cameron for successfully defending his thesis!

May 2017:
Chad is an ACS/ESBES International Graduate Student Design Challenge Finalist

April 2017:
Dr. Epps Delivers the Lindsay Lecture at Texas A&M University

April 2017:
Kaleigh wins the Richard Wool Award for Women in Green Engineering

March 2017:
The Epps group is featured in UDaily Tuning Block-polymers

March 2017:
Cameron wins best DPOLY poster at APS 2017 March Meeting

October 2016:
Dr. Epps Delivers the Thiele Lecture at the University of Notre Dame

August 2016:
UD Hosts the 2016 Future Faculty Workshop

June 2016:
Announcing the 2016 Future Faculty Workshop to be held at UD

June 2016:
The Epps group welcomes Spencer, a summer REU student!

June 2016:
Epps group collaboration with DuPont Performance Materials announced

May 2016:
Congratulations to Ming for successfully defending his thesis!

May 2016:
Congratulations to Dr. Epps for his promotion to professor!

May 2016:
Congratulations to Chad for receiving the Saurabh A. Palkar Graduate Award for Mentoring

April 2016:
Congratulations to Melody for receiving the Robert L. Pigford Teaching Assistant Award

April 2016:
Congratulations to Kai for successfully defending his thesis!

March 2016:
Congratulations to Victoria for being named a 2016 Barry Goldwater Scholar

March 2016:
Victoria receives 2nd Place in the ACS Undergraduate Research in Polymer Science Symposium

December 2015:
Congratulations to Angela for successfully defending her thesis!

October 2015:
Congratulations to Dr. Epps for receiving the 2016 American Physical Society Dillon Medal

June 2015:
Congratulations to Dr. Epps for receiving the 2015 AIChE Owens Corning Early Career Award!

May 2015:
Angela is selected to speak at the AIChE 08A Excellence in Graduate Polymer Research Award Symposium

May 2015:
Tom is awarded the Paul H. Schipper Fellowship

April 2015:
Angela is awarded a UD Dissertation Fellowship

April 2015:
The Epps’ group battery membrane research was featured in the UDaily

March 2015:
Tom is awarded NSF GRFP Honorable Mention

March 2015:
Congratulations to Angela for being selected to speak at the 2015 Polymers Gordon Research Seminar

March 2015:
Kaleigh is selected to attend the 65th Lindau Nobel Laureate Meeting

February 2015:
Chad's work on light-sensitive polymers for controlled gene silencing is featured on materialsviews.com

January 2015:
Ming and Cameron’s work on XPS depth profiling highlighted at Nanotechweb.org

January 2015:
Rashida is awarded a NSF Systems Biology of Cells in Engineered Environments IGERT Fellowship

Epps Research Group Highlighted Projects

Valorization of Biomass
Because of its natural abundance, lignocellulosic biomass is being widely investigated as a renewable feedstock that could serve as an alternative to petroleum-derived chemicals. Although significant advances in its utilization have been developed, there remains great opportunity in the valorization of renewable biomass to create value-added materials. One approach to achieve this goal is in the use of tailoring polymer chemistry to create high-value polymeric materials from biomass sources.
bio-polymers

An area of emphasis in the Epps group is the synthesis of functionalized monomers from these renewable feedstocks, with a particular focus on lignin-derived compounds. Lignin can be depolymerized into its building blocks, which can then be modified to create monomers for the synthesis of new materials through controlled radical, ring-opening, anionic, and cationic polymerizations. Additionally, inherent functionalities on lignin aromatics can be helpful to mitigate the toxicity concerns of conventional aromatics. Of particular interest to our group is developing structure-property relationships of these materials and investigating ways to valorize biomass feedstocks such as making biobased monomers for 3D printing, generating lignin-derived steric stabilizers for fabrication of sustainable MOF/polymer composites, and using bio-based catalysts for synthesizing components of sustainable thermoset-forming systems.


Renewable Polymers from Waste Streams

Renewable polymers are needed to help reduce global dependence on petrochemicals. Many renewable polymers are also biodegradable, biocompatible, and beneficial for a variety of applications, such as compostable cups and cutlery, elastomeric shoe soles and car tires, sturdy machine parts and electronics casings, and compatibilizing agents. Lignin and fatty acids are two of the most abundant renewable waste streams that can contribute to the collection of renewable (biobased) polymers already available. Lignin is a byproduct from pulp and paper mill manufacturing and typically is burned for energy. Fatty acids can come from waste cooking oils and sometimes are fed to livestock or converted to biofuels. Alternatively, these renewable resources can provide lignin model compounds (LMCs) shown structurally in the figure and n-alkyl (“fatty”) alcohols of varying aliphatic chain-length and degree of saturation. We can incorporate such LMCs and fatty alcohols into materials through functionalization and subsequently polymerization. The functional handles and structural diversity in these biobased monomers provide means for adjusting properties to our needs. Thus, we are interested in de novo design of practical lignin- and fatty acid-based polymers, such as polycarbonate resins and block copolymer thermoplastic elastomers, to create next-generation plastics.

bio-polymers

Another significant waste stream that holds promise as a source of renewable polymers is plastics waste. While mechanical methods of recycling plastics are commonly used, these methods require extensive sorting of waste streams, are limited to certain plastic chemistries, and result in recycled plastics which retain only a fraction of their value. Using an extremely diverse approach, including catalytic methods, polymer chemistry, and process engineering, a large degree of plastics waste can be converted into valuable products, including highly functional materials and commodity chemicals for industrial and consumer uses. Plastics waste can also be converted into monomer feedstocks for the renewable production of new plastics which retain high value. This project addresses longstanding questions in chemical recycling and upcycling in order to develop fundamental tools and approaches to make better use of plastics waste as a feedstock. The findings will ultimately lead to more sustainable plastics as well as overall reduction of waste.

bio-polymers


Nanostructured Polymer for Ion-Conduction

Lithium-ion batteries are a rapidly-growing industry with widespread applications and superior performance in comparison to other energy storage devices.  Block polymer electrolytes show promise in addressing some of the safety and performance limitations of the current liquid electrolytes in lithium-ion batteries.  We are interested in designing block polymer electrolytes that can transport lithium ions efficiently to reduce charging times, have sufficient mechanical strength to reduce lithium dendrite growth that can cause short-circuiting between electrodes, and are processible via inexpensive means.

Tapered block polymers are block polymers with interfacial regions that taper from one polymer block to another polymer block (in a well-defined fashion over a well-defined region of the copolymer).  These materials are of high interest because the tuning of monomer sequence gives rise to higher ionic conductivities, favorable nanostructures with well-connected ion-conducting pathways, and improved processibilities in comparison to non-tapered analogues while maintaining the desired chemistry and mechanical properties.

SAXS tapered

Block polymer/homopolymer blends also present an opportunity to improve ionic conductivity and processibility.  The appropriate combination of polymer molecular weights enables the formation of homopolymer-rich channels that act as “superhighways” for lithium ions.

DMA tapered

The precise quantification of structural characteristics of the block polymer electrolytes allows us to identify key parameters that govern the material properties.  Experimental techniques such as reflectometry provide nanometer-level resolution to ascertain distributions of monomer segments and ions, while computational modeling suggests mechanistic insights into block polymer assembly.  This understanding allows us to advance our material designs efficiently.

DMA tapered


Polymer/MOF Composites

The incorporation of porous nanoparticles into polymers to form mixed matrix and fiber-based composites is a burgeoning area relevant in applications such as separations, catalysis, drug delivery, and protection.  In particular, metal-organic frameworks (MOFs) are highly tunable materials with extraordinarily high surface areas.  Adding MOFs to polymers, which also are highly tunable, offers advantages over other systems.

Polymer-based composites fabricated with MOFs have inherent advantages over traditional composites because of the partially organic nature of MOFs; however, shortcomings still exist, such as agglomeration of MOF crystals, defects at the MOF-polymer interface, and a lack of systematic configurations (e.g., arrays) of MOFs within polymers.  We are interested in utilizing lignin-derived polymers as steric stabilizers for metal organic frameworks (MOFs) and process them into nanofiber composites via electrospinning to attain comparable or better composite properties as that of the petroleum-derived polymeric counterparts.

Engineering of the MOF-polymer interface can be achieved through altering the MOF crystal as well as changing processing conditions used to fabrication composites.  In the former, some of the organic linkers on some MOFs can be modified using acyl chloride chemistry to impart functional groups with similar chemical makeup to the polymer, which results in reduced defects as well as better dispersion of MOF crystals in both film and fiber forms.

 

SAXS tapered

Techniques used to mix preformed MOFs with polymers leads to active materials for several applications; however, these composites often suffer from particle agglomeration that occurs during processing of the composite.  An alternative strategy is to seed polymers with MOF precursor salts and then grow crystals after polymer processing has occurred.  Changing the metal type, salt anion, and concentration affects solution viscosity and conductivity, which translates to changes in processing.  Metals dispersed within the fabricated composites act as nucleation centers for in situ growth of MOFs.

DMA tapered


Polymer Thin Films

thermally_responsive_AFM

Many applications and devices require controlled distribution of material functionality in multiple dimensions. At the nanometer length scale, attempts to meet this challenge have included template-mediated materials chemistry. Interest in block copolymers has evolved because of their potential use in numerous nanotechnologies including nanotemplating, filtration membranes, and organic optoelectronics (LEDs and photovoltaics). Self-assembly of block copolymers in thin films is a complex phenomenon. A large parameter space, including film thickness, annealing conditions (thermal or solvent), molecular mass, and surface energy, governs the film morphology. Surface energetics and interface interactions also direct morphology orientation.

The behavior of thermally-responsive block copolymers compounds this complexity. When a thermally-responsive block copolymer undergoes a thermal transition resulting in a mass loss, the parameter space expands to include volume fraction shift, thickness decrease, surface energetic shifts of the relative blocks, and a change in substrate and free surface energetics. The resulting phenomenon is impacted by the complexity of multiple and often co-dependent variables. Control in chemically amplified transformations such as in thermal deprotection reactions can prove extremely useful especially when the self-assembly of the block copolymer is affected. Current investigations include controlling the final self-assembled morphology and orientation of thermally-responsive block copolymers using different surface chemistries and fabrication techniques as well as high-throughput methods for rapid characterization and identification of critical parameters.

An important aspect of exploiting high-throughput methods has been the development of novel gradient fabrication devices to efficiently probe the effects of substrate surface energy/chemistry and annealing conditions on block copolymer thin film morphology. These gradient approaches are becoming increasingly important for mapping the phase behavior of new materials for specific applications. In the following example, we used controlled vapor deposition to generate a gradient in substrate surface energy/chemistry and we show how the orientation of a cylinder-forming PS-b-PMMA thin film evolves with changes in substrate surface chemistry from a pure benzyl silane monolayer on silicon (left) to a pure methacryl silane monolayer on silicon (right), with gradient compositions and morphologies shown in between.

thin film

We have also designed a solvent resistant microfluidic mixing device that produces discrete gradients in solvent vapor composition and/or concentration to quickly and easily examine the use of solvent mixtures (versus a single solvent) for controlling thin film self-assembly. The image below shows a schematic of our solvent vapor annealing setup with the microfluidic device and its use as a screening tool to locate phase transformations in a poly(styrene-b-isoprene-b-styrene) triblock copolymer as a function of solvent composition and swollen film thickness.

microfluidic mixing device


Polymeric Assemblies for Nucleic Acid Delivery

Polymeric nanomaterial assemblies have several attractive features including tunability, control over the size and structure of the assemblies, and enhanced stability. Furthermore, the chemical versatility of polymers enables the incorporation of various stimuli-responsive moieties. Our group is interested in exploiting these valuable properties to develop polymer assemblies, which could be utilized in a broad range of applications.
?????????????????????????????????????????We are currently focusing on biomedical aspects such as nucleic acid and small molecule drug delivery. Controlled release of these therapeutics is widely recognized as one of the most significant challenges hindering clinical success. To this end, our lab has designed and synthesized novel photo-responsive block copolymers to bind and encapsulate nucleic acids and mediate efficient release upon application of the photo-stimulus. We have implemented a variety of strategies to expand the versatility of our platform, including formation of mixed polymer carriers to tune the amount of siRNA released, incorporation of anionic excipients for theranostics, and development of a hybrid lipid-polymer formulation to efficiently transfect human primary cells. Furthermore, elucidation of the mechanisms that underlie the gene silencing process has facilitated the design of a simple mathematical model to predict the kinetics of siRNA-mediated gene silencing.

conf_cells2-r11svn

Thomas

Thomas H. Epps, III

Allan & Myra Ferguson Distinguished Professor of Chemical & Biomolecular Engineering
Professor of Materials Science & Engineering
Director; Center for Research in Soft matter & Polymers (CRiSP)
Director; Center for Hybrid, Active, and Responsive Materials (CHARM) - NSF MRSEC
Deputy Director; Center for Plastics Innovation (CPI) - DOE EFRC
University of Delaware

Phone: 302.831.0215
Fax: 302.831.1048
Email: thepps@udel.edu
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Recent Honors & Awards

-Percy L. Julian Award (NOBCChE), 2020
-University of Minnesota, Chemical Eng. and Materials Science Centennial & Jubilee Alumni Lecture, 2020
-Fellow of the Royal Society of Chemistry, 2018
-APS Fellow, 2017
-Thiele Lectureship, University of Notre Dame, 2016
-Graduate Students of Diversity Lectureship, University of Massachusetts, Amherst, 2016
-APS John H. Dillon Medal, 2016
-AIChE Owens Corning Early Career Award, 2015
-Kavli Fellow, National Academy of Sciences, 2014
-Sigma Xi Young Investigator Award, 2014
-Thomas & Kipp Gutshall Professorship, 2012
-Martin Luther King, Jr. Visiting Professor Award, 2012
-UD Gerard J. Mangone Best Young Scholar Award (Alison Young Professor), 2011
-DuPont Young Professor Award, 2010