Ring/Chain versus Network: Architecture Induced by Self- versus Pairwise-Association of Telechelic Polymers

• Main Author: Li, Boyu
• Format: Others
• Published: 2016
• Online Access: https://thesis.library.caltech.edu/9805/1/Boyu%20Li%27s%20thesis.pdf; Li, Boyu (2016) Ring/Chain versus Network: Architecture Induced by Self- versus Pairwise-Association of Telechelic Polymers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9NS0RTW. https://resolver.caltech.edu/CaltechTHESIS:05272016-171126982 <https://resolver.caltech.edu/CaltechTHESIS:05272016-171126982>

<p>Non-covalent associations, including hydrophobic interaction or ionic interaction for self-association, and metal coordination or hydrogen-bonding for complementary-association, have been widely used as key interactions in supramolecules formation with telechelic associative polymers. And a specific application of long associative telechelic polymers has been developed by our group for the mist-control and drag-reduction of liquid fuels. During the research on this project, self- and pairwise-associative telechelic polymers are able to be compared for the first time, and are shown to display distinct associative patterns. In order to design materials with the desired properties, it is imperative to understand the relationships between polymer chemical structure and their topology and dynamics.</p> <p>In this thesis, self-associative telechelic polymer refers to α,ω-di(isophthalic acid) polycyclooctadiene (DA-PCOD), which can associate with itself through its acid ends. When tertiary amine-ended polymer is added into the mixture, isophthalic acid preferably associates pairwisely with tertiary amine due to the higher binding strength of charge-assisted hydrogen bond. And the 1:1 molar ratio mixture of α,ω-di(isophthalic acid) and α,ω-di(di(tertiary amine)) PCOD (DA/DB-PCOD) is named as pairwise-associative telechelic polymers. DA-PCOD is capable of multimeric association via directional hydrogen bonding due to the specific chemical structure of the isophthalic acid end, while DA/DB-PCOD exhibits dynamics that strikingly resembles that for linear covalent polymers. Temperature determines the binding strength of self- and pairwise- end association, and furthermore, the fraction of unbound ends and the distribution and topology of formed supramolecules/aggregates. Polymer length affects the dynamics of DA-PCOD mainly through determining the concentration of the end groups. And the net effect of chain length on the dynamics of DA/DB-PCOD is non-monotonic and varies with the specific temperature and concentration. The knowledge of structure-property relationships obtained from this work will enable future design of end group entities and other properties of these associative telechelic polymers for their specific applications.</p>