Hierarchical Porosity in Carbons Derived from Hypercrosslinked Emulsion-Templated Polymers

Seminars
14.06.2018
14:30
David Wang Auditorium, 3rd floor Dalia Maydan Bldg.

Mrs. Sima Israel, PhD. Candidate

Technion – Israel Institute of Technology, Department of Materials
Science and Engineering
Haifa 3200003, Israel
simais@campus.technion.ac.il

Microporous polymers are commonly used for gas storage, separation processes, and catalysis. The
carbonization of microporous polymers can be used to generate porous carbons for a range of “green”
energy applications including supercapacitors, batteries, fuel cells, and hydrogen storage. In many such
applications, the presence of a porous hierarchy, from macroporous to microporous, is integral to
functionality. PolyHIPEs (PHs) are macroporous polymers synthesized within high internal phase
emulsions (HIPEs), emulsions in which the dispersed phase occupies over 74% of the volume. PHs are of
interest for such applications as chemical synthesis, chromatography, ion exchange, separation, sensing,
tissue engineering, and controlled drug delivery.
In this research, polymers with unique and advantageous hierarchical porous architectures were
synthesized by hypercrosslinking PHs (PH-X). The macroporous PH monoliths, synthesized within
HIPEs containing styrene, vinylbenzyl chloride (VBC), and divinylbenzene, were hypercrosslinked in a
post-synthesis Friedel-Crafts reaction. Hypercrosslinking introduced microporosity, yielding specific
surface areas (SAs) as high as 1652 m2/g. The synthesis of interpenetrating polymer networks (IPN) PHs
introduced mesoporosity, enhancing the hierarchical porosity. These microporous PHs were evaluated for
their performance in sorption applications that included exposure to a variety of organic solvents,
exposure to a variety of organic vapors, and exposure to aqueous solutions containing organic
contaminants. Their performance was superior to the PHs that did not undergo hypercrosslinking and to a
commercial activated carbon.
Carbons monoliths with similar hierarchical porosities were synthesized from the hypercrosslinked PHs.
Hypercrosslinking a VBC-based PH with a SA of 8.9 m2/g introduced microporosity, increasing the SA to
808 m2/g, while retaining the macroporous architecture. The carbonization of PH-X (PH-X-P) yielded a
porous carbon monolith with a nodular wall structure, reducing the SA to 553 m2/g. Adding a porogen to
the PH successfully enhanced the carbon microporosity, achieving an SA as high as 800 m2/g.

Michael S. Silverstein.