Ab initio studies of novel polymer cross-linkers
department or school: Science, Irving K. Barber Faculty of (Okanagan)
department or school: Chemistry, Department of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Pei, Zhipeng
issued: 2021-04-22T19:49:55Z
issued: 2021
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: A polymer cross-linker is a chemical agent that can create covalent bonds between the molecular chains that comprise a polymeric material. Recently, a novel, versatile, bis-diazirine based polymer cross-linker was reported,1 but its cross-linking efficacy is relatively low and can be improved. Moreover, the details of the mechanism of cross-linking has not been reported. In this thesis, we use state-of-art computational chemistry methods to explore how carbenes derived from bis-diazirines engage in cross-linking and identify the factors that affect the cross-linking efficacy. The computational results show that bis-diazirines do not form bis-carbenes in a concerted fashion upon thermal activation. Instead, the carbene centers are generated sequentially. The use of substituents on the carbene center (i.e. p-X-C6H4-C̈-R) and para to the carbene center can significantly influence the electronic state of carbenes, as well as the barrier heights associated with carbene formation and carbene insertion. Therefore, substitution provides a general strategy to control the reactivity of the cross-linker. We also explore how tether units and different ring structures may impact cross-linker performance, and possible carbene side- and self-reactions. To the best of our knowledge, this is the first computational study on this type of polymer cross-linker, and the results provide guidance and insights for improving cross-linking performance systematically. The data obtained were used to propose a next-generation diazirine-based polymer cross-linker.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/77910
note: Ab Initio Studies of Novel Polymer Cross-Linkers by Zhipeng Pei B.Sc., The Australian National Univerisity, 2017 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Chemistry) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) April 2021 © Zhipeng Pei, 2021 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis/dissertation entitled: Ab Initio Studies of Novel Polymer Cross-Linkers submitted by Zhipeng Pei in partial fulfillment of the requirements of the degree of Master of Science Gino DiLabio, Department of Chemistry, Irving K. Barber Faculty of Science Supervisor Frederic Menard, Department of Chemistry, Irving K. Barber Faculty of Science Supervisory Committee Member Kevin Smith, Department of Chemistry, Irving K. Barber Faculty of Science Supervisory Committee Member Kevin Golovin, School of Engineering, Faculty of Applied Science University Examiner iii Abstract A polymer cross-linker is a chemical agent that can create covalent bonds between the molecular chains that comprise a polymeric material. Recently, a novel, versatile, bis-diazirine based polymer cross-linker was reported,1 but its cross-linking efficacy is relatively low and can be improved. Moreover, the details of the mechanism of cross-linking has not been reported. In this thesis, we use state-of-art computational chemistry methods to explore how carbenes derived from bis-diazirines engage in cross-linking and identify the factors that affect the cross-linking efficacy. The computational results show that bis-diazirines do not form bis-carbenes in a concerted fashion upon thermal activation. Instead, the carbene centers are generated sequentially. The use of substituents on the carbene center (i.e. p-X-C6H4-C̈-R) and para to the carbene center can significantly influence the electronic state of carbenes, as well as the barrier heights associate…
has type: Thesis/Dissertation
date issued: 2021-05
is shown at: 10.14288/1.0396918
language: eng
degree discipline: Chemistry
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/77910