Insight into the Competitive Adsorption Behavior of Polymer Chains in Silica Nanopores by Small-Angle Neutron Scattering

Xuchun Wang, Xingyi Lyu, Xun Wu, Lilin He, Jessica V. Lamb, Alexander S. Filatov, Massimiliano Delferro, Wenyu Huang, Byeongdu Lee

Research output: Contribution to journalArticlepeer-review

Abstract

Processive hydrogenolysis catalysts, in which a metal nanoparticle (e.g., Pt) embedded at the bottom of a cylindrical silica nanopore can repeatedly cleave polymer chains and produce value-added hydrocarbon products, offer a potential solution for billions of tons of waste plastics. As the chain stays longer near the Pt catalysts, it would have a higher chance of getting cut, and therefore the molecular weight distribution of the product could be affected by the adsorption behavior of virgin chains (long polymers) versus cleaved chains (short polymers) into the nanopores. This work reports a model study to understand the competitive adsorption behavior of the two different molecular weight polymers that are mixed, mimicking the reaction medium in the intermediate stage of the catalytic reaction. This study employs small-angle neutron scattering (SANS), which takes advantage of contrast differences between hydrogenous and deuterated polystyrenes to experimentally observe the relative composition of the two polymers in the silica nanopores. Our results reveal preferential adsorption of longer chains in the silica nanopores, which is consistent with the theoretical prediction in the literature for the case of the enthalpic attraction between polymers and pore walls.

Original languageEnglish
JournalMacromolecules
DOIs
StateAccepted/In press - 2024

Funding

We appreciate Max Meirow for stimulus discussions and thoughtful comments on the manuscript. This work was supported as part of the Institute for Cooperative Upcycling of Plastics (iCOUP), an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences. Argonne National Laboratory is operated by UChicago Argonne LLC under Contract DE-AC-02-06CH11357 for the United States Department of Energy, and Ames Laboratory under Contract DE-AC-02-07CH11358 is operated by Iowa State University for the United States Department of Energy. Work performed at the Center for Nanoscale Materials and Advanced Photon Source, both U.S. Department of Energy Office of Science User Facilities, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The LiX beamline is part of the Center for BioMolecular Structure (CBMS), which is primarily supported by the National Institutes of Health, National Institute of General Medical Sciences (NIGMS) through a P30 Grant (P30GM133893), and by the DOE Office of Biological and Environmental Research (KP1605010). LiX also received additional support from NIH Grant S10 OD012331. As part of NSLS-II, a national user facility at Brookhaven National Laboratory, work performed at the CBMS is supported in part by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences Program under contract number DE-SC0012704. This research also used resources at the High Flux Isotope Reactor (HFIR), a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam times were allocated to HFIR on proposal numbers IPTS-31435 and IPTS-31935.

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