Interfacial structure of polymers near a surface: a molecular dynamics study

Ravi Dutta     

PhD candidate, School of Chemical Engineering, UQ


Abstract: Mixed Matrix Membranes (MMMs) are considered as attractive materials that demonstrate outstanding separation characteristics, and have been conventionally prepared by incorporating inorganic fillers such as zeolites, metal organic framework (MOFs), carbon nanotubes (CNTs) and porous graphene in a polymer matrix. The success of MMMs depends greatly on the screening and selection of suitable polymer matrix, inorganic filler and interaction between them. The past decade has witnessed substantial progress in both the fundamental and application aspects of MMMs in gas separation, however, interface problems such as the formation of non-selective voids, rigidified polymer and pore blockage are still challenging. Hence, understanding and minimising interfacial barriers between the polymer and the inorganic filler are critical to the design and optimisation of such processes; however, trial and error experimentation is required to address these non-ideal interface issues. On the other hand, atomistic simulations have become an important complement to experiments in the screening and selection of suitable materials in MMMs, and have the potential to reduce this trial and error process. In this work, we report strategies to minimise the interfacial defects that exists at the interface between organic and inorganic phase, considering a model MMM consisting of polyimide (PI) polymer and ZIF-8 filler, using a combination of equilibrium Molecular Dynamics (EMD) simulations and Density functional theory (DFT) calculations. The results demonstrate that non-selective voids of nanometre size exist near the filler surface that reduce perm-selectivity. The inclusion of ionic liquids at the interface between the polymer and filler is found to be a better alternative to avoid these defects, and to improve the membranes performance.


Bio: Ravi Dutta is a research scholar at the UQ School of chemical engineering, working under the supervision of Prof. Suresh K. Bhatia. His thesis entitled “Interfacial structure of polymers near a surface: a molecular dynamics study” aims to develop an understanding of polymer structure near a solid surface in order to facilitate better design of mixed matrix membranes for gas separation.



Carbon-based cathode materials for aluminium-ion batteries

Shaikat Debnath    

PhD student, Bernhardt Group, AIBN, UQ


Abstract: In aluminum-ion batteries (AIB), a graphite cathode shows very promising electrochemical performance. However, its low capacity and high volume expansion is a major hindrance. This is due to the limited intercalation of the AlCl4- ion into the graphite layers. As a possible solution to this, hydrogen substituted graphdiyne (HsGDY), a 2D carbon allotrope with large octahedral shaped pores, and nitrogen doped graphite C11N1 are tested as potential cathode materials here by density functional theory (DFT) calculations. It was expected that the large pores of HsGDY can increase the cathode’s capacity of hosting more AlCl4 intercalants and facilitate a smaller volume change as well as increase the rate of diffusion between layers. From our results it is found that HsGDY poses a single layer theoretical electrical capacity of 456mAh/g, which is much higher than the single layer theoretical electrical capacity of graphite (124mAh/g). On the other hand, C11N1 is also found to possess high theoretical electrical capacity of 185mAh/g, which is higher than graphite and other reported carbon nitrates (C3N1). However regarding expansion, both of the materials showed similar behavior as graphite. Further calculations will be conducted to understand the thermal stability and diffusion properties of the materials as potential cathode materials of AIBs.


Bio: Mr. Shaikat Debnath is a PhD student at Australian Institute for Bioengineering and Nanotechnology, and has a UQ-Research Training Scholarship to support his research. He is working in Debra Bernhardt’s group, where his research area is carbon-based cathode materials for aluminium-ion batteries. Before that he did his Master of Engineering Science from University of Malaya, Malaysia in 2015 and Bachelor in Electrical and Electronic Engineering from Chittagong University of Engineering and Technology, Bangladesh in 2009.


AIBN Seminar Room