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Full-Text Articles in Engineering
Rheological Characterization Of Liquid-To-Solid Transitions In Bulk Polyelectrolyte Complexes, Yalin Liu, Brian Momani, H. Henning Winter, Sarah L. Perry
Rheological Characterization Of Liquid-To-Solid Transitions In Bulk Polyelectrolyte Complexes, Yalin Liu, Brian Momani, H. Henning Winter, Sarah L. Perry
Chemical Engineering Faculty Publication Series
Polyelectrolyte complexation has long been known to result in both liquid and solid complexes. However, the exact nature of the liquid-to-solid transition remains an open question. We have used rheology to explain this phenomenon for the model system of poly(4-styrenesulfonic acid, sodium salt) (PSS) and poly(diallyldimethyl ammonium chloride) (PDADMAC) in the presence of potassium bromide (KBr). The use of a time-salt superposition allows for a detailed analysis of changes in the linear viscoelastic response for both liquid complex coacervates and solid polyelectrolyte complexes as a function of salt concentration, and facilitates unambiguous determination of the mechanism for this phase transition. …
The Effect Of Comb Architecture On Complex Coacervation, Brandon M. Johnston, Cameron W. Johnston, Rachel A. Letteri, Tyler K. Lytle, Charles E. Sing, Todd Emrick, Sarah L. Perry
The Effect Of Comb Architecture On Complex Coacervation, Brandon M. Johnston, Cameron W. Johnston, Rachel A. Letteri, Tyler K. Lytle, Charles E. Sing, Todd Emrick, Sarah L. Perry
Chemical Engineering Faculty Publication Series
Complex coacervation is a widely utilized technique for effecting phase separation, though predictive understanding of molecular-level details remains underdeveloped. Here, we couple coarse-grained Monte Carlo simulations with experimental efforts using a polypeptide-based model system to investigate how a comb-like architecture affects complex coacervation and coacervate stability. Specifically, the phase separation behavior of linear polycation-linear polyanion pairs was compared to that of comb polycation-linear polyanion and comb polycation-comb polyanion pairs. The comb architecture was found to mitigate cooperative interactions between oppositely charged polymers, as no discernible phase separation was observed for comb-comb pairs and complex coacervation of linear-linear pairs yielded stable …
A Student-Created, Open Access, Living Textbook, Sualyneth Galarza, Sarah L. Perry, Shelly Peyton
A Student-Created, Open Access, Living Textbook, Sualyneth Galarza, Sarah L. Perry, Shelly Peyton
Chemical Engineering Faculty Publication Series
Textbooks are expensive, updated infrequently, and rarely used effectively by students. We discuss here a way for students to create the textbook for the course, helping them feel ownership over the course material. This Wiki-based, student-created textbook is online free for use, widely accessible by all, and editable during the course of and as topics evolve. This type of textbook format is particularly well suited to upper-level electives on topics that are rapidly emerging. We have nucleated a student created textbook here, fully online and open access, for two upper elective courses in chemical engineering. Wikis offer an easy-to-learn platform …
Microfluidics: From Crystallization To Serial Time-Resolved Crystallography, Shuo Sui, Sarah L. Perry
Microfluidics: From Crystallization To Serial Time-Resolved Crystallography, Shuo Sui, Sarah L. Perry
Chemical Engineering Faculty Publication Series
Capturing protein structural dynamics in real-time has tremendous potential in elucidating biological functions and providing information for structure-based drug design. While time-resolved structure determination has long been considered inaccessible for a vast majority of protein targets, serial methods for crystallography have remarkable potential in facilitating such analyses. Here, we review the impact of microfluidic technologies on protein crystal growth and X-ray diffraction analysis. In particular, we focus on applications of microfluidics for use in serial crystallography experiments for the time-resolved determination of protein structural dynamics.
Sequence And Entropy-Based Control Of Complex Coacervates, Li-Wei Chang, Tyler K. Lytle, Mithun Radhakrishna, Joel J. Madinya, Jon Vélez, Charles E. Sing, Sarah L. Perry
Sequence And Entropy-Based Control Of Complex Coacervates, Li-Wei Chang, Tyler K. Lytle, Mithun Radhakrishna, Joel J. Madinya, Jon Vélez, Charles E. Sing, Sarah L. Perry
Chemical Engineering Faculty Publication Series
Biomacromolecules rely on the precise placement of monomers to encode information for structure, function, and physiology. Efforts to emulate this complexity via the synthetic control of chemical sequence in polymers are finding success; however, there is little understanding of how to translate monomer sequence to physical material properties. Here we establish design rules for implementing this sequence-control in materials known as complex coacervates. These materials are formed by the associative phase separation of oppositely charged polyelectrolytes into polyelectrolyte dense (coacervate) and polyelectrolyte dilute (supernatant) phases. We demonstrate that patterns of charges can profoundly affect the charge–charge associations that drive this …
Strain-Stiffening Gels Based On Latent Crosslinking, Yen H. Tran, Matthew J. Rasmuson, Todd Emrick, John Klier, Shelly Peyton
Strain-Stiffening Gels Based On Latent Crosslinking, Yen H. Tran, Matthew J. Rasmuson, Todd Emrick, John Klier, Shelly Peyton
Chemical Engineering Faculty Publication Series
Gels are an increasingly important class of soft materials with applications ranging from regenerative medicine to commodity materials. A major drawback of gels is their relative mechanical weakness, which worsens further under strain. We report a new class of responsive gels with latent crosslinking moieties that exhibit strain-stiffening behavior. This property results from the lability of disulfides, initially isolated in a protected state, then activated to crosslink on-demand. The active thiol groups are induced to form inter-chain crosslinks when subjected to mechanical compression, resulting in a gel that strengthens under strain. Molecular shielding design elements regulate the strain-sensitivity and spontaneous …