Clustering in Aqueous Pentaethylenehexamine (PEHA) Solutions

Importance of the formation of giant clusters in solutions is becoming increasingly recognized. However, little attention has been paid to the formation of giant clusters in solutions of small, relatively soluble but non-amphiphilic molecules. In this work, it was presented a general methodology based on molecular dynamics that can be used to investigate such systems. As a case study, the focus was on the formation of apparently stable clusters of pentaethylenehexamine (PEHA) in water. These clusters have been used as templates for the construction of bioinspired silica nanoparticles. To better understand clustering in this system the effect of PEHA protonation state (neutral, +1, and +2) and counterion type (chloride or acetate) on PEHA clustering in dilute aqueous solutions (200 mM and 400 mM) using large-scale classical molecular dynamics was studied.

"We find that large stable clusters are formed by singly-charged PEHA with chloride or acetate as the counterion.Large clusters also appear to be stable for doubly-charged PEHA with acetate, the less soluble counterion. We attribute this behavior to a form of complex coacervation, observed here for relatively small and highly soluble molecules (PEHA + counterion) rather than the large polyions usually found to form such coacervates. This work might help future studies of additives for the design of novel bio-inspired templated nanomaterials." (Dr. Nassrr Afify)

Employed Research Services

"Classical molecular dynamics simulations were carried out on the Eddie cluster, using the large-scale atomic/molecular massively parallel simulator (LAMMPS) code. The LAMMPS code was compiled using Intel compiler available on Eddie. The optional “INTEL acceleration package” available in LAMMPS was included during the compilation process. This has significantly improved the simulation speed. Each molecular dynamics simulation utilised 16-core Eddie computing node for several days." (Dr Nasser Afify)

The Digital Research Services employed were the following:

• Cloud Storage - To store the data acquired during the study
• Eddie - To conduct the analysis performed in this work

Dr Nasser Afify is Research Associate in the Institute for Materials and Processes (IMP). You can find him on ResearchGate or LinkedIn.

• Sweatman, Martin B., et al. "Molecular dynamics investigation of clustering in aqueous glycine solutions." The Journal of Physical Chemistry B 126.25 (2022): 4711-4722.
• McHale, Glen, et al. "The liquid Young’s law on SLIPS: Liquid–liquid interfacial tensions and Zisman plots." Langmuir 38.32 (2022): 10032-10042.
• Tan, Jiazheng, et al. "Cluster formation in symmetric binary SALR mixtures." The Journal of Chemical Physics 154.7 (2021): 074504.
• Afify, N. D., and M. B. Sweatman. "Preferential heating of aqueous amine solutions using infrared radiation at selected vibrational frequencies: A molecular dynamics study." The Journal of Chemical Physics 151.2 (2019): 024503.
• Afify, N. D., and Martin B. Sweatman. "Molecular dynamics simulation of microwave heating of liquid monoethanolamine (MEA): An evaluation of existing force fields." The Journal of Chemical Physics 148.20 (2018): 204513.
• Afify, Nasser D., and Martin B. Sweatman. "Classical molecular dynamics simulation of microwave heating of liquids: the case of water." The Journal of Chemical Physics 148.2 (2018): 024508.

Why don't you explore featured projects demonstrating the use of similar resources and related training opportunities? Have a look at the carousels below.