About

Kenneth Shull is a Professor of Materials Science and Engineering at Northwestern University. His research focuses on using fundamental understandings of polymer physics to explore the self-assembly, mechanics, and applications of soft materials. His work often involves characterizing materials on the nanometer scale and probing the 'meso' scales that exist between nanoscopic and bulk levels. The aim of his research is to understand how molecular processes influence observable bulk properties, with the goal of developing a deep fundamental understanding of the physical behavior of polymeric materials. This knowledge is used to enhance current applications of advanced materials and to introduce new applications. Professor Shull has received significant recognition for his contributions, including being named a Fellow of the American Physical Society in 2002, receiving the NSF Young Investigator Award from 1994 to 1999, and earning departmental and advising awards at Northwestern. His research has contributed to the understanding of the physical behavior of polymers and soft materials, impacting both scientific knowledge and practical applications in materials science.

Research topics

• Materials science
• Composite material
• Computer Science
• Nanotechnology
• Engineering
• Artificial Intelligence
• Chemical engineering
• Organic chemistry
• Chemistry
• Process engineering
• Biological system
• Mechanical engineering
• Physics
• Photochemistry
• Nuclear chemistry
• Optoelectronics
• Inorganic chemistry
• Optics

Selected publications

• Composite material homogenization for shear wave elastography of muscle-like fiber-laden viscoelastic waveguides under prestress

  SSRN Electronic Journal · 2026-01-01

  preprintOpen access
  PublisherDOI

• Allomelanin-Inspired Polyurethane Nanocomposites with Multi-Radiation Resistance and Enhanced Mechanical Properties

  ACS Applied Materials & Interfaces · 2025-06-30 · 3 citations

  article

  Approaches for protecting polymeric materials against ionizing radiation are of importance for applications including in space, in aseptic medical devices, and in the nuclear industry. Allomelanin is a specific subclass of nitrogen-free melanin found to play a key role in the protection of fungal species in extreme environments. Herein, we prepared allomelanin-inspired nanomaterials by oxidatively polymerizing dihydroxynapthalene (DHN) isomers 1,7-DHN and 2,3-DHN. We demonstrate that these materials can be easily dispersed into a polyurethane (PU) elastomer, yielding products with tunable mechanical properties and optical transparency. We show that at loadings as low as 0.25 wt %, this approach provides UVB protection to the PU matrix maintaining mechanical properties despite exposure, preservation of composite surface chemistry, and suppression of crack formation. Furthermore, we show that these composites maintain their mechanical properties after exposure to gamma irradiation, demonstrating the multiradiation protective effect of these allomelanin-inspired nanomaterials.

  PublisherDOI

• Efficient Formation of a Carbohydrate-Based Polyelectrolyte Complex Gel with Macroscopic Homogeneity

  ACS Applied Polymer Materials · 2025-12-15 · 1 citations

  articleSenior authorCorresponding

  Biobased polyelectrolyte complexes (BioPECs) have attracted considerable attention due to their unique properties and potential applications in various fields. However, the processability of BioPECs often remains a challenge because of the insolubility of the solution components and of the complex itself. In this study, we develop an alkalinization method for BioPEC complexation, which enables uniform gel complexation from a single-phase precursor solution. The complexation time has been significantly reduced in comparison to a previously developed acidification method. The mechanical properties of BioPECs prepared by both methods were characterized using the quartz crystal microbalance (QCM) and in situ shear rheometry with a porous base plate that was used to study the reversible nature of the complexation process. The difference in local polymer concentration at the substrate surface was determined before and after the complexation. These concentration measurements demonstrate a unique capability of the QCM for determining equilibrium phase behavior in a two-phase polymer solution. Our findings demonstrate the feasibility and advantages of the alkalinization method for fast and scalable BioPEC complexation, which can facilitate the development and application of BioPECs in various fields.

  PublisherDOI

• Thermomechanical Characterization of High <i>T</i>_g Disulfide-Containing Thermoplastic Polyimides

  Macromolecules · 2025-02-07 · 4 citations

  articleSenior authorCorresponding

  Covalent adaptable networks are frequently studied as alternatives to conventional thermosetting polymers because they can be recycled and reprocessed; however, the inclusion of dynamic covalent bonds within high-temperature (or high-performance) engineering thermoplastics remains largely unexplored. In this work, dynamic disulfide-containing thermoplastic polyimides were synthesized and compared to nondynamic thermoplastic polyimides. The thermomechanical properties of these polymers were examined by utilizing several techniques, including thermogravimetric analysis, differential scanning calorimetry, along with the use of the rheometric quartz crystal microbalance, and traditional dynamic mechanical analysis. The resulting experimental data suggest that the thermal stability of the dynamic compositions was slightly reduced in comparison to the nondynamic analogs, but the dynamic compositions exhibit a similar mechanical response under service conditions. The dynamic compositions also demonstrated significantly easier reprocessability via compression molding than their nondynamic counterparts.

  PublisherDOI

• Tailoring Architecture and Properties of Biodegradable Aliphatic-Aromatic Copolyesters via Interfacial Polymerization

  ACS Applied Materials & Interfaces · 2025-11-06 · 1 citations

  article

  Aliphatic-aromatic copolyesters (AAPEs) are widely used in biodegradable packaging due to their balance of thermal stability and enzymatic degradability. However, their synthesis is often hindered by time-consuming protocols, prolonged reactions, and reliance on expensive metal catalysts. Herein, we introduce stirred interfacial polymerization as a rapid, open-air method to synthesize poly(p-phenylene adipate-co-terephthalate) (PPAT) with tunable aliphaticity. We compare the use of chloroform, a conventional organic solvent for interfacial polymerization, with ethyl acetate, a more environmentally friendly alternative. Regardless of the solvent used, we achieved reaction yields that matched or exceeded those of traditional step-growth synthesis methods. Increasing the concentration of phase transfer catalyst enhances the incorporation of the aliphatic monomer, promoting a shift from a random to a more block-like copolymer structure. PPAT powder can be readily heat-pressed into semicrystalline films with degradation onset temperatures between 263 and 310 °C and tailored elastic moduli and hardness values. Furthermore, increased aliphaticity significantly improved enzymatic degradation by PETase, with films containing ∼60% of poly(p-phenylene adipate) units showing over 50% mass loss within 400 h. This work outlines an efficient synthetic pathway for producing enzymatically degradable AAPEs with tailored backbone structures, crystallinity, and thermomechanical properties.

  PublisherDOI

• Mechanical characterization of an incompressible, strain-hardening, transversely isotropic material

  Acta Biomaterialia · 2025-11-03

  articleOpen accessSenior authorCorresponding

  A strain energy approach for the characterization of strain-hardening, transversely isotropic materials was developed and validated through a combination of indentation and uniaxial extension experiments. These experiments were utilized because they can also be applied to directly measure the mechanical properties of many living tissues, including muscle. Model materials with transversely isotropic mechanical properties broadly representative of biological tissues were utilized in the experiments. These organogels were made from acrylic triblock copolymer solutions with an aligned cylindrical domain morphology. The strain energy function used here was proposed recently by Hegde et al., and is based on the three independent linear elastic constants for a transversely isotropic material, along with two additional strain-hardening parameters. These five parameters were determined for the model material by indentation with a blade indenter aligned both parallel and perpendicular to the unique axis of the gel, and by uniaxial extension of the material along the directions parallel and perpendicular to the unique axis. The effect on the indentation curves of an applied tensile pre-stress applied along the unique axis was also investigated. Finite element modeling was used to generate interpolated functions that allow the elastic constants, along with their uncertainty, to be obtained from the experimental data in a straightforward manner. These parameters were then used to predict the wave speeds in pre-stressed material that would be measured by shear wave elastography, a commonly used technique for non-invasively characterizing the mechanical properties of biological tissues.

  PublisherDOI

• Real-Time Visualization of Single Polymer Conformational Change in the Bulk State during Mechanical Deformation

  Physical Review Letters · 2025-04-09 · 5 citations

  article

  Although polymers are most often used within bulk materials, investigating their conformations and dynamics has long been a challenging endeavor in this configuration, particularly under external forces. Addressing this, we utilize single-molecule localization microscopy as a powerful imaging tool to visualize bottlebrush poly(n-butyl acrylate) chains in the bulk state under spherical indentation, quantitatively describing changes in behavior of single polymer chains. We compare these experiments to displacement fields determined analytically and confirmed through finite element analysis. This study pioneers visualizing polymer conformational changes in their native environment in situ, offering transformative insights into polymer behavior and dynamics.

  PublisherDOI

• Challenges for Implementing Polymer Gels in Defense Applications

  River Publishers eBooks · 2025-08-07

  book-chapter

  Polymer gels are soft, lightly crosslinked polymers that are highly swollen with solvent. The gel properties can be tuned by manipulating the polymer and solvent chemistry, solvent loading, polymer and solvent chain architecture, and the incorporation of various fillers and additives. This tunability provides broad utility in military applications including electronic devices, sensors, robotics, multi-functional textiles, responsive coatings, combat medical care, and tissue surrogates for ballistic testing. While potentially useful, a number of challenges can hinder gel utility for the Army. This paper describes recent efforts that offer promise to overcome these obstacles, including improving operational temperature performance and gel toughness.

  PublisherDOI

• Wave propagation in prestressed and transversely isotropic viscoelastic structures: Inverse modeling challenges in elasticity imaging

  The Journal of the Acoustical Society of America · 2025-04-01

  article

  The functional role and structure of skeletal muscle results in anisotropy in both material properties and imposed stresses, as well as waveguide effects. Dynamic elastography reconstruction methods for estimating muscle tissue viscoelastic properties that are rooted in assumptions of isotropy and bulk wave motion may produce inaccurate estimates. The superposition of axially aligned orthotropy (transverse isotropy) in material properties and axially aligned prestress conditions due to passive stretch or muscle activation makes it difficult to independently discern how much of the apparent anisotropy is due to the muscle material or the imposed stress field. Furthermore, this stress field may result in large strain conditions that require the use of higher-order terms in the stress–strain relationship. The significance of these confounding conditions and strategies for decoupling material and stress-based anisotropy are investigated with a series of numerical finite element studies based on simple and morphological image-informed geometries, and experimental elastography studies using scanning laser Doppler vibrometry and magnetic resonance elastography.

  PublisherDOI

• Mechanical Characterization of an Incompressible, Strain-Hardening, Transversely Isotropic Material

  SSRN Electronic Journal · 2025-01-01

  preprintOpen accessSenior author
  PublisherDOI

Recent grants

• PIRE: Computationally-Based Imaging of Structure in Materials (CuBISM)

  NSF · $4.2M · 2017–2024

• Crack Propagation in Self-Healing Polymer Gels with High Toughness

  NSF · $312k · 2009–2013

• Deposition, Equilibrium Structure and Mechanical Response of Polyelectrolyte Complexes

  NSF · $413k · 2017–2020

• Interfacial Mechanics and Contact Properties of Model Membranes

  NSF · $354k · 2005–2009

• Collaborative Research: Modern Oil-based Paints: A Mechanistic Approach to Assessing and Modeling their Curing, Aging and Cleaning

  NSF · $405k · 2012–2016

Frequent coauthors

• Mónica Olvera de la Cruz

  Northwestern University

  27 shared

• Alfred J. Crosby

  University of Massachusetts Amherst

  23 shared

• Dongchan Ahn

  Dow Chemical (United States)

  23 shared

• Kazi Sadman

  Materials Science & Engineering

  17 shared

• Hongxia Guo

  16 shared

• Michelle L. Nunalee

  Duke University

  16 shared

• Qifeng Wang

  Beihang University

  16 shared

• Muzhou Wang

  Northwestern University

  14 shared

Labs

• Shull Research GroupPI

Awards & honors

• Fellow, American Physical Society, 2002
• NSF Young Investigator Award, 1994–99
• Department Teacher of the Year, 1995
• McCormick Adviser of the Year, 1998