(687d) Leveraging Nanoparticle Template Assembly and Interfacial Phenomenon for Multi-Scale Control over Polyimide-Derived Carbon Molecular Sieve Films

Synthetic challenges common to carbon molecular sieve (CMS) and other inorganic membrane materials include the need to minimize defect-free membrane thickness while simultaneously tailoring membrane texture and function in order to break through permeability-selectivity trade-offs. In this talk, we will present a facile hard-templating approach [1], which we have recently extended to produce ultra-thin microporous polyimide-derived CMS films that are self-supported on three-dimensionally ordered mesoporous (3DOm) carbon layers. This approach exploits convectively deposited, size-tunable silica nanoparticle colloidal crystal films as a sacrificial template and poly (pyromellitic dianhydride-co-4,4’-oxydianiline) (PAA) as the carbon source used for replicating the template voids. Replication is carried out by tuning viscosity of the PAA molecular replica precursor solution to facilitate infiltration into the template voids by simple immersion, followed by controlled spin-off of excess precursor. Precursor spin-off rates and the multi-layer thickness of the sacrificial template itself provide handles for independently controlling the thickness of the CMS over-layer and the supporting 3DOm underlayer, respectively. Beyond scaffolding film mesostructure and asymmetry, we will demonstrate how the three-dimensionally distributed template-replica interface can be exploited as an additional handle for tuning microstructure of the carbon matrix [2]. Specifically, we will discuss complementary high-resolution TEM, Raman, XPS, physisorption, and permeation data demonstrating how interfacial chemistries can be employed to tailor carbon allotrope distribution (e.g., sp² carbon allotrope content) and thus microporosity and its distribution in CMS films. In doing so, we will aim to develop critical synthesis-structure-function relations that should help establish the versatility of the simple nanoparticle crystalline film platform for facile templating of hierarchically micro-mesostructured thin films and membranes.

References

[1] Z. Tian, M. A. Snyder, Langmuir, 30 (2014) 9828-9837.

[2] M. A. Snyder, MRS Bulletin, 41(9) (2016) 683-688.