Diazaborole Linked Porous Polymers: Design, Synthesis, and Application to Gas Storage and Separation

Author

Zafer KahveciFollow

DOI

https://doi.org/10.25772/MMAG-C340

Defense Date

2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Prof. Hani El-Kaderi

Second Advisor

Prof. Scott Gronert

Third Advisor

Prof. Indika U. Arachchige

Fourth Advisor

Prof. James T. McLeskey

Abstract

The synthesis of highly porous organic polymers with predefined porosity has attracted considerable attention due to their potential in a wide range of applications. Porous organic polymers (POPs) offer novel properties such as permanent porosity, adjustable chemical nature, and noteworthy thermal and chemical stability. These remarkable properties of the POPs make them promising candidates for use in gas separation and storage. The emission of carbon dioxide (CO₂) from fossil fuel combustion is a major cause of global warming. Finding an efficient separation and/or storage material is essential for creating a cleaner environment. Therefore, the importance of the POPs in the field is undeniable. Along these pursuits, several porous polymers have been synthesized with different specifications. The first class of porous polymers are called Covalent Organic Frameworks (COFs). They possess highly ordered structures with very high surface areas and contain light elements. COFs based on B-O, C-N, and B-N bonds have been reported so far. In particular, COFs based on B-O bond formation are well investigated due to the kinetically labile nature of this bond which is essential for overcoming the crystallization problem of covalent networks. Along this line, triptycene-derived covalent organic framework (TDCOF-5) has been synthesized through a condensation reaction between 1, 4-benzenediboronic acid and hexahydroxytriptycene which leads to the formation of boronate ester linkage. TDCOF-5 has the highest H₂ uptake under 1 atm at 77K (1.6%) among all known 2D and 3D COFs derived from B–O bond formation and moderate CO₂ uptake (2.1 mmol g^-1) with Qst values of 6.6 kJ mol^-1 and 21.8 kJ mol^-1, respectively.

The second class of porous structures discussed herein is diazaborole linked polymers (DBLPs). They are constructed based on B-N bond formation and possess amorphous structures due to the lack of the reversible bond formation processes. At this scope, 2, 3, 6, 7, 14, 15-hexaaminotriptycene (HATT) hexahydrocloride was synthesized and reacted with different boronic acid derivatives to produce three different porous polymers under condensation reaction conditions. DBLP-3, -4 and -5 have very high surface areas; 730, 904, and 986 m² g^-1, and offer high CO₂ uptake (158.5, 198, and 171.5 mg g^-1) at 1 bar and 273 K, respectively. DBLPs have much higher CO₂ uptake capacity when compared to almost all reported B-N and B-O containing porous polymers in the field. In addition to high CO₂ capacity, DBLPs showed remarkable CO₂/N₂ and CO₂/CH₄ selectivity, when the Henry`s law of initial slope selectivity calculations were applied. In general, DBILPs exhibit high selectivities for CO₂/N₂ (35-51) and CO₂/CH₄ (5-6) at 298 K which are comparable to those of most porous polymers.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

7-24-2015