2026-09-19T04:28:51Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1534042024-01-25T03:31:06Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Smith, Zachary P.
Mizrahi Rodriguez, Katherine
Massachusetts Institute of Technology. Department of Materials Science and Engineering
2024-01-24T19:28:52Z
2024-01-24T19:28:52Z
2022-05
2024-01-16T18:28:17.922Z
https://hdl.handle.net/1721.1/153404
Over the past forty years, membrane-based gas separations have emerged as a promising alternative to energy-intensive separation processes such as amine absorption and cryogenic distillation. However, a trade-off between permeability and selectivity as well as issues of decreased performance at high pressures have hindered widespread membrane deployment. In response, there is a growing body of research aimed to developing materials formulations that address these polymer-specific disadvantages. Polymers of intrinsic microporosity (PIMs) were designed as ultrahigh-free-volume materials with inefficient chain packing and high surface areas, resulting in pure-gas performance beyond that of traditional glassy polymers. Hybrid systems such as mixed-matrix membranes (MMMs) also emerged as a means of increasing overall separation performance and reducing plasticization. Despite the surge in available material platforms for membrane-based separations, the performance and fundamental underpinnings of binary and ternary mixed-gas transport in these microporous polymers and MMMs remains underexplored.
This thesis combines synthetic chemistry, materials science, and chemical engineering to develop a platform of functionalized PIM derivatives and to investigate their pure- and mixed-gas transport properties in industrially relevant conditions. Approaches to increase diffusion-based performance in PIMs are developed, including methods to functionalize PIMs with carboxylic acid and amine functionalities, template free volume elements through protection/de-protection chemistries, and fabricate MOF–polymer composites. The effects of polymer functionalization, free volume manipulation, and membrane hybridization on transport are investigated via pure-gas testing and sorption–diffusion analysis, to elucidate structure–property relationships between polymer packing structure and gas diffusion. Polymers with identical backbone structures and varying backbone functionality are subsequently used as a platform to investigate the effects of CO₂ sorption affinity on the binary and ternary mixed-gas transport. Among the PIMs considered, amine-functionalized PIM-1 shows a notable increase in mixed-gas selectivity compared to the pure-gas case. The generalizability of this approach is investigated through aminefunctionalization of a different family of polymers, poly(aryl ether)s (PAEs). Results indicate that amine-functionalization can serve as a promising route to increase mixed-gas transport performance while also reducing CO₂-based plasticization. The influence of CO₂ sorption affinity on transport is finally investigated through ternary mixed-gas tests in toxic gas mixtures containing H₂S. Taken together, this thesis derives connections between macromolecular chemistry and complex gas transport performance in PIMs. By developing these structure-property-performance relationships, this work provides context for the potential of PIMs in industrial applications and rational design handles for future development of high-performing membrane solutions.
Ph.D.
Massachusetts Institute of Technology
In Copyright - Educational Use Permitted
Copyright MIT
http://rightsstatements.org/page/InC-EDU/1.0/
Mixed-gas Transport in Microporous Polymer Derivatives for Energy-Efficient Gas Separations
Thesis
application/pdf
Doctoral
Doctor of Philosophy
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="92b3afec-b407-4202-b190-c1d7cd8ef5f1">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Title>Mixed-gas Transport in Microporous Polymer Derivatives for Energy-Efficient Gas Separations</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2022-05</PublicationDate>
<Authors>
<Author>
<DisplayName>Mizrahi Rodriguez, Katherine</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://rightsstatements.org/page/InC-EDU/1.0/</License>
<Abstract>Over the past forty years, membrane-based gas separations have emerged as a promising alternative to energy-intensive separation processes such as amine absorption and cryogenic distillation. However, a trade-off between permeability and selectivity as well as issues of decreased performance at high pressures have hindered widespread membrane deployment. In response, there is a growing body of research aimed to developing materials formulations that address these polymer-specific disadvantages. Polymers of intrinsic microporosity (PIMs) were designed as ultrahigh-free-volume materials with inefficient chain packing and high surface areas, resulting in pure-gas performance beyond that of traditional glassy polymers. Hybrid systems such as mixed-matrix membranes (MMMs) also emerged as a means of increasing overall separation performance and reducing plasticization. Despite the surge in available material platforms for membrane-based separations, the performance and fundamental underpinnings of binary and ternary mixed-gas transport in these microporous polymers and MMMs remains underexplored.
This thesis combines synthetic chemistry, materials science, and chemical engineering to develop a platform of functionalized PIM derivatives and to investigate their pure- and mixed-gas transport properties in industrially relevant conditions. Approaches to increase diffusion-based performance in PIMs are developed, including methods to functionalize PIMs with carboxylic acid and amine functionalities, template free volume elements through protection/de-protection chemistries, and fabricate MOF–polymer composites. The effects of polymer functionalization, free volume manipulation, and membrane hybridization on transport are investigated via pure-gas testing and sorption–diffusion analysis, to elucidate structure–property relationships between polymer packing structure and gas diffusion. Polymers with identical backbone structures and varying backbone functionality are subsequently used as a platform to investigate the effects of CO₂ sorption affinity on the binary and ternary mixed-gas transport. Among the PIMs considered, amine-functionalized PIM-1 shows a notable increase in mixed-gas selectivity compared to the pure-gas case. The generalizability of this approach is investigated through aminefunctionalization of a different family of polymers, poly(aryl ether)s (PAEs). Results indicate that amine-functionalization can serve as a promising route to increase mixed-gas transport performance while also reducing CO₂-based plasticization. The influence of CO₂ sorption affinity on transport is finally investigated through ternary mixed-gas tests in toxic gas mixtures containing H₂S. Taken together, this thesis derives connections between macromolecular chemistry and complex gas transport performance in PIMs. By developing these structure-property-performance relationships, this work provides context for the potential of PIMs in industrial applications and rational design handles for future development of high-performing membrane solutions.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>