PEO-PPO-PEO Surfactant Mixtures as Templates for Silicas With Very Large Cylindrical Mesopores at Ambient Temperature and With Helical Mesopores at Sub-Ambient Temperature

<p>The original research described herein concerns the synthesis of mesoporous silicas through a surfactant-templating method. The approach taken involved the use of a mixed surfactant system of two poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) surfactants, with one of the copolymers containing a much larger percentage of hydrophobic (PPO) blocks than the employed co-surfactant. Systematic adjustments of experimental parameters initially enabled the preparation of 2-D hexagonally ordered mesoporous silicas (SBA-15) of uncommonly large pore diameter at ambient temperature. Comparable silica was synthesized with and without temperature control. Additional adjustments to experimental parameters, including reduction of the relative amount of framework precursor used in the synthesis, led to the synthesis of counterpart single-micelle templated silica nanotubes of record pore size at ambient temperature. The pores sizes of the silica nanotubes were able to be tuned by adjustment of the volume of swelling agent added during synthesis, and synthesis was possible without temperature control and at several fixed temperatures around ambient temperature. A remarkable development in the described study of the mixed surfactant system was the discovery of a facile method for production of hollow helical silica structures with large inner pore spaces at considerable scale. These structures have only been attainable in the past at high expense, and presumably in limited quantities.</p>

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Chemistry

Grantor

The Graduate School and University Center of The City University of New York

Year dc:date.available

2020

Author dc:creator

• Beaton, Laurance

Advisors dc:contributor.advisor

• Michal Kruk
• Nan-Loh Yang

Committee member dc:contributor.committeemember

• Mark Kobrak

• Chemistry
• Materials Chemistry
• Polymer Chemistry
• mesoporous
• nanomaterials
• SBA-15
• silicas
• nanotubes

Repository record dc:identifier

https://academicworks.cuny.edu/gc_etds/4075

OAI identifier oai:identifier

oai:academicworks.cuny.edu:gc_etds-5152