Date of Award

Fall 10-12-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Dr. Robson F Storey

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Dr. Jeffrey S. Wiggins

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Dr. Derek L. Patton

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Dr. William L. Jarrett

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Dr. Xiaodan Gu

Committee Member 5 School

Polymer Science and Engineering

Abstract

Polyisobutylene (PIB) is a fully saturated, aliphatic polymer of high commercial importance due to its superior gas barrier properties and high chemical/oxidative stability. One commercial end-use for PIB is in insulated glass windows (IGU), where it acts as a gas/moisture barrier and sealant. Under certain adverse conditions, catastrophic failure of the PIB sealant may result in aesthetic and functional failure of the IGU, which necessitates replacement of the unit. Thus, there exists a need to improve current generations of thermoplastic PIB sealants to be able to withstand the harsh environments found in current real-world applications.

In the first project, we synthesized a library of PIB macromers bearing (meth)acrylate moieties via the acid catalyzed cleavage/alkylation of poly(isobutylene-co-isoprene) (butyl rubber) or via living polymerization and subsequent reactive end-quenching with phenoxyalkyl acrylates. The macromers were then crosslinked in the presence of a photoinitiator using UV light, and the curing kinetics were measured. The viscoelastic and tensile properties of the resulting networks were then tested and compared.

In the second project, nitrile containing small molecules were added in the presence of cationized PIB chain ends to study their quenching efficiency. This technique, known as the Ritter reaction, represents a hitherto unreported route towards acrylamide functionalized telechelic PIBs. Under a variety of conditions, we demonstrated that PIB substrates were prone to carbocationic rearrangement rather than amide formation, but we successfully synthesized a new family of oligo-isbutenyl acrylamides via this route.

In the third project, we demonstrated that quenchers derived from resorcinol, a commodity chemical derived from certain wood species, displayed superior quenching efficiency compared to known alkoxybenzenes. These quenchers were synthesized to possess a variety of functional groups, and the highly active phenyl ring allowed for quantitative quenching at significantly reduced time frames while simultaneously requiring lower Lewis acid demand compared to previously studied alkoxybenzenes.

In the fourth project, we investigated the efficacy of 2,6-di-tert-butylphenol, a common antioxidant, as a quenching agent in the aforementioned cleavage/functionalization reaction. The resulting PIBs contained a mixture of mono- and di-tert-butylphenol moieties covalently bound to the PIB backbone and chain ends, which displayed superior resistance towards thermal and thermo-oxidative degradation compared to commercially available PIBs and PIBs synthesized via living polymerization.

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