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1. Decoupling of Mechanical and Transport Properties in Organogels via Solvent Variation

   https://doi.org/https://doi.org/10.3390/gels7020061  

   Mineart, Kenneth P. ; Hong, Cameron ; Rankin, Lucas A. ( May 2021 , Gels)

   Di Chenna, Pablo H. (Ed.)

   Organogels have recently been considered as materials for transdermal drug delivery media, wherein their transport and mechanical properties are among the most important considerations. Transport through organogels has only recently been investigated and findings highlight an inextricable link between gels’ transport and mechanical properties based upon the formulated polymer concentration. Here, organogels composed of styrenic triblock copolymer and different aliphatic mineral oils, each with a unique dynamic viscosity, are characterized in terms of their quasi-static uniaxial mechanical behavior and the internal diffusion of two unique solute penetrants. Mechanical testing results indicate that variation of mineral oil viscosity does not affect gel mechanical behavior. This likely stems from negligible changes in the interactions between mineral oils and the block copolymer, which leads to consistent crosslinked network structure and chain entanglement (at a fixed polymer concentration). Conversely, results from diffusion experiments highlight that two penetrants—oleic acid (OA) and aggregated aerosol-OT (AOT)—diffuse through gels at a rate inversely proportional to mineral oil viscosity. The inverse dependence is theoretically supported by the hydrodynamic model of solute diffusion through gels. Collectively, our results show that organogel solvent variation can be used as a design parameter to tailor solute transport through gels while maintaining fixed mechanical properties. 

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2. Gaming self-consistent field theory: Generative block polymer phase discovery

   https://doi.org/10.1073/pnas.2308698120  

   Chen, Pengyu ; Dorfman, Kevin D. ( November 2023 , Proceedings of the National Academy of Sciences)

   Block polymers are an attractive platform for uncovering the factors that give rise to self-assembly in soft matter owing to their relatively simple thermodynamic description, as captured in self-consistent field theory (SCFT). SCFT historically has found great success explaining experimental data, allowing one to construct phase diagrams from a set of candidate phases, and there is now strong interest in deploying SCFT as a screening tool to guide experimental design. However, using SCFT for phase discovery leads to a conundrum: How does one discover a new morphology if the set of candidate phases needs to be specified in advance? This long-standing challenge was surmounted by training a deep convolutional generative adversarial network (GAN) with trajectories from converged SCFT solutions, and then deploying the GAN to generate input fields for subsequent SCFT calculations. The power of this approach is demonstrated for network phase formation in neat diblock copolymer melts via SCFT. A training set of only five networks produced 349 candidate phases spanning known and previously unexplored morphologies, including a chiral network. This computational pipeline, constructed here entirely from open-source codes, should find widespread application in block polymer phase discovery and other forms of soft matter.

    

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3. Polyamide nanofiltration membrane with highly uniform sub-nanometre pores for sub-1 Å precision separation

   https://doi.org/10.1038/s41467-020-15771-2  

   Liang, Yuanzhe ; Zhu, Yuzhang ; Liu, Cheng ; Lee, Kueir-Rarn ; Hung, Wei-Song ; Wang, Zhenyi ; Li, Youyong ; Elimelech, Menachem ; Jin, Jian ; Lin, Shihong ( April 2020 , Nature Communications)

   Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes.

    

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4. Numerical calculation of interstitial dumbbell-mediated transport coefficients in dilute crystalline systems with non-truncated correlations

   https://doi.org/10.1080/14786435.2022.2120646  

   Chattopadhyay, Soham ; Trinkle, Dallas R ( December 2022 , Philosophical Magazine)

   Interstitial dumbbell-mediated diffusion can affect segregation and precipitation properties of solutes in alloys under irradiated conditions. Accurate computation of transport coefficients for dumbbell-mediated diffusion thus becomes essential for modelling solute segregation under irradiation. In this work, we extend the Green’s function approach, a general numerical approach, to compute accurate transport coefficients for interstitial dumbbell-mediated mechanisms in the dilute limit for arbitrary crystalline systems with non-truncated correlations in atomic diffusion. We also present results of tracer correlation factors, solute drag ratios and partial diffusion coefficient ratios in iron and nickel-based alloys computed with our approach, compare our results with existing results in the literature, and discuss some aspects of correlated solute-dumbbell motion. 

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5. Theoretical and Experimental Considerations for Investigating Multicomponent Diffusion in Hydrated, Dense Polymer Membranes

   https://doi.org/10.3390/membranes12100942  

   Mazumder, Antara ; Dobyns, Breanna M. ; Howard, Michael P. ; Beckingham, Bryan S. ( October 2022 , Membranes)

   In many applications of hydrated, dense polymer membranes—including fuel cells, desalination, molecular separations, electrolyzers, and solar fuels devices—the membrane is challenged with aqueous streams that contain multiple solutes. The presence of multiple solutes presents a complex process because each solute can have different interactions with the polymer membrane and with other solutes, which collectively determine the transport behavior and separation performance that is observed. It is critical to understand the theoretical framework behind and experimental considerations for understanding how the presence of multiple solutes impacts diffusion, and thereby, the design of membranes. Here, we review models for multicomponent diffusion in the context of the solution-diffusion framework and the associated experiments for characterizing multicomponent transport using diffusion cells. Notably, multicomponent effects are typically not considered when discussing or investigating transport in dense, hydrated polymer membranes, however recent research has shown that these effects can be large and important for understanding the transport behavior. 

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