Chemical & Biomolecular Engineering
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Below is a list of selected recent publications by our faculty. This is to provide a general overview of the rich and diverse topics that our faculty and students work on. A detailed list of publications can be accessed via individual faculty pages (and in their group webpages, google scholar profiles, etc.)

Number of surface sites and turnover frequencies for oxide catalysts (January 2022)

Israel E. Wachs

 

The Solution is the Solution: Data-Driven Elucidation of Solution-to-Device Feature Transfer for π-Conjugated Polymer Semiconductors (16 January 2022)

Connor P. Callaway, Aaron L. Liu, Rahul Venkatesh, Yulong Zheng, Myeongyeon Lee, Carson Meredith, Martha Grover, Chad Risko, Elsa Reichmanis

Data analytics techniques coupled with materials informatics provides opportunities to accelerate the discovery and development of organic semiconductors for electronic devices. This Perspective outlines steps required to incorporate a comprehensive informatics methodology into experimental development of polymer-based organic semiconductor technologies, where data-driven approaches offer predictive capabilities previously unattainable via traditional experimental means.

Induced activation of the commercial Cu/ZnO/Al203 catalyst for the steam reforming of methanol (20 January 2022)

Didi Li, Fang Xu, Xuan Tang, Sheng Dai, Tiancheng Pu, Xianglin Liu, Pengfei Tian, Fuzhen Xuan, Zhi Xu, Israel E. Wachs, Minghui Zhu 

An induced activation strategy was developed to manipulate the catalyst surface reconstruction process for the supported Cu/ZnO/Al2O3 catalyst for methanol steam reforming by controlling the composition of reducing agents during catalyst activation. This treatment resulted in increasing the long-term catalyst stability by threefold and catalytic activity enhanced by twofold.                                                                                  

Single-pot Fabrication of Cellulose-Reinforced Solid Polymer Lithium-Ion Conductors (23 February 2022)

Helen Wong, Nian Liu, Elsa Reichmanis

Polymer electrolytes present a promising alternative to conventional liquid electrolytes for flexible power needed for portable electronic systems due to higher mechanical integrity and lower risk of leaking solvent. Here, we demonstrate a ‘single-pot’ synthetic approach using a non-toxic cellulose additive that affords a flexible, free-standing solid polymer electrolyte. The results providea path towards sustainable, polymer electrolytes with performance metrics suitable for applications having lower energy demand.Polymer electrolytes present a promising alternative to conventional liquid electrolytes for flexible power needed for portable electronic systems due to higher mechanical integrity and lower risk of leaking solvent. Here, we demonstrate a ‘single-pot’ synthetic approach using a non-toxic cellulose additive that affords a flexible, free-standing solid polymer electrolyte. The results provide a path towards sustainable, polymer electrolytes with performance metrics suitable for applications having lower energy demand. 

Molecular Design of Supported MoOx Catalysts with Surface TaOx Promotion for Olefin Metathesis (23 February 2022)

Bin Zhang, Shuting Xiang, Anatoly I. Frenkel, Israel E. Wachs

Surface modification of Al2O3 by tantalum oxide shifted the anchoring sites of MoOx on Al2O3. These changes in anchoring sites of MoOx resulted in an increasing number of active sites with higher specific activity (TOF).

 

Towards a chemistry-informed paradigm for designing molecules (March 2022)

Christopher Rzepa, Srinivas Rangarajan

This invited opinion article describes the importance of including chemistry information and constraints in molecule design and discusses approaches and specific applications for chemistry-cognizant molecule discovery.
Comparing the energy requirements for amine absorption processes for CO2 capture (March 2022)

Samuel J. Layding, Hugo S. Caram

The minimum and operating stripper reboiler duties for amine regeneration are estimated using a simple thermodynamic method that only uses the stripper pressure, the rich and lean loading of the sorbent and the temperature approach in the cold side of the crossflow heat exchanger. 
Gelation phase diagrams of colloidal rod systems measured over a large composition space (27 April 2022)
Shiqin He, Marco Caggioni, Seth Lindberg, Kelly M. Schultz
 
Rheological modifiers tune product rheology with a small amount of material. This work builds gelation phase diagrams of two colloidal rod rheological modifiers using bulk rheology and microrheology measurements. These phase diagrams will provide a guide to determine the composition needed for desired rheological properties and eliminate trial-and-error experiments during product formulation.
Characterizing Nonuniform Hydrogel Elastic Moduli Using Autofluorescence (16 May 2022)
John A. McGlynn, Kelly M. Schultz
 
Hydrogel biomaterials show promise as implantable cell delivery vehicles that enhance tissue regeneration and the natural healing process. The design of these materials requires that they mimic the natural environment to retain native cell function.
Competing Time Scales in Surface-Driven Solution Depolymerization (14 October 2022)

Polymers that can undergo controlled or triggered depolymerization have garnered significant interest due to their use as recyclable or degradative materials. A variety of “self-immolative” chemistries have been developed, where this depolymerization process proceeds either spontaneously or upon application of a stimulus. 

Liquid-Liquid Transition in Water from First Principles (15 December 2022)
Thomas E. Gartner, III, Pablo M. Piaggi, Roberto Car, Athanassios Z. Panagiotopoulos, Pablo G. Debenedetti

A long-standing question in water research is the possibility that supercooled liquid water can undergo a liquid-liquid phase transition (LLT) into high- and low-density liquids. We used several complementary molecular simulation techniques to evaluate the possibility of an LLT in an ab initio neural network model of water trained on density functional theory calculations with the SCAN exchange correlation functional.

Dynamic Emissivity of Self-Assembled Magnetoresponsive Janus Particle Chain Suspensions (30 December 2023)
Jinghui Gao, Samuel R. Wilson-Whitford, Sang Eon Han, Sang M. Han, James F. Gilchrist
 
Suspensions of magnetoresponsive Janus colloids form chains and undergo alignment under the influence of a magnetic field. When the magnetic field is aligned with a light path, light transmission through the sample increases as compared to randomly or orthogonally oriented chains. 
The transition from Elasto-Hydrodynamic to Mixed Regimes in Lubricated Friction of Soft Solid Surfaces (13 February 2023)
Hao Dong, Nichole Moyle, Haibin Wu, Constantine Yuri Khripin, Chung-Yuen Hui, Anand Jagota
 
Lubricated contacts in soft materials are common in various engineering and natural settings, such as tires, haptic applications, contact lenses, and the fabrication of soft electronic devices. Two major regimes are elasto-hydrodynamic lubrication (EHL), in which solid surfaces are fully separated by a fluid film, and mixed lubrication (ML), in which there is partial solid-to-solid contact. 
A new approach for determining roughness by means of contact angles on solids (8 March 2023)

RJ Good, MK Chaudhury, C Yeung

Contact angle hysteresis on rough surfaces is caused by the contortion of the liquid surface that must occur as the liquid front passes from one metastable configuration to another. We have combined the Wenzel equation for the effect of roughness on the contact angle, 0, with the well-known equation relating contact angles to the surface free energy of the solid and of the liquid, and with Good’s hypothesis of a free energy barrier to liquid front motion.
Controlling neocortical epileptic seizures using forced temporal spike-time stimulation: an in silico computational study (28 June 2023)
Joseph Schmalz, Rachel V. Quinarez, Mayuresh V. Kothare, Gautam Kumar
 
 Epileptic seizure is typically characterized by highly synchronized episodes of neural activity. Existing stimulation therapies focus purely on suppressing the pathologically synchronized neuronal firing patterns during the ictal (seizure) period. While these strategies are effective in suppressing seizures when they occur, they fail to prevent the re-emergence of seizures once the stimulation is turned off. 
A novel “feed-backward” control structure for on-demand control of distillation column sequences (7 August 2023)
Jessica L. Barry, Jacob A. Thompson, Jonas Baltrusaitis, William L. Luyben
 
The typical conventional plantwide control structure sets the flow rate of the fresh feed entering the process. Sometimes marketing or safety requirements dictate that the flowrate of the product leaving the process must be flow controlled. This structure is called “on-demand.”
Nutrient-Doped Hydroxyapatite: Structure, Synthesis and Properties (16 August 2023)
Mohamed Ammar, Sherif Ashraf, Jonas Baltrusaitis

Complex inorganic powders based on calcium phosphates have found a plethora of practical applications. Of particular interest are the CaO-P2O5 system-based multi-component material powders and granules as the source of major- and micronutrients for the plants.