Synthesis of norbornyl benzocyclobutene ladder polymers and the transport of gases therein

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Industrial chemical separations account for 15% of the world's energy consumption, and therefore developing energy-efficient separation technologies represents a critical need for sustainability. Compared to traditional energy-intense separation processes such as chemisorption and distillation, membrane separations can save up to ten times more energy. However, the persisting challenge to develop membranes with both high permeability and selectivity has hampered widespread industrial adoption of membrane separations. Polymers of intrinsic microporosity (PIM) have recently emerged as promising next-generation membrane materials for gas separation due to their abundant and tunable microporosity. However, PIMs have limited structural diversity and often exhibit very high permeability but only moderate selectivity, hindering their tuning of properties and applications for gas separations. In this thesis, the catalytic arene-norbornene annulation (CANAL) was developed to synthesize rigid microporous ladder-shaped polymers with norbornyl benzocyclobutene backbones in high molecular weights. The versatile and efficient CANAL reaction enabled the synthesis of a myriad of CANAL polymers with diverse functionalities and backbone conformations. Robust freestanding films can be formed by solvent casting of these polymers. By systematically varying chemical structures of these polymers, we have been able to tune the gas transport properties in their films and develop understanding on the structure-transport property relationships for these microporous polymers. The gas permeability can be enhanced without compromising their selectivity by varying the substituents on the polymers. The selectivity can be significantly improved by introducing 3-D twists along the polymer ladder backbones through the incorporation of five-membered rings. The resulting polymers exhibit an unprecedented combination of high selectivity and permeability. Detailed studies of their transport mechanisms revealed that the remarkable performance is a result of the highly selective diffusion barriers in the polymers films, while maintaining high permeability through micropores.


Type of resource text
Form electronic resource; remote; computer; online resource
Extent 1 online resource.
Place California
Place [Stanford, California]
Publisher [Stanford University]
Copyright date 2020; ©2020
Publication date 2020; 2020
Issuance monographic
Language English


Author Lai, Holden Wan Hong
Degree supervisor Xia, Yan, 1980-
Thesis advisor Xia, Yan, 1980-
Thesis advisor Frank, C. W
Thesis advisor Waymouth, Robert M
Degree committee member Frank, C. W
Degree committee member Waymouth, Robert M
Associated with Stanford University, Department of Chemistry.


Genre Theses
Genre Text

Bibliographic information

Statement of responsibility Holden Wan Hong Lai.
Note Submitted to the Department of Chemistry.
Thesis Thesis Ph.D. Stanford University 2020.
Location electronic resource

Access conditions

© 2020 by Holden Wan Hong Lai
This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).

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