| dc.description.abstract | Polyurethanes (PUs) comprise an important class of polymers that are used for a multitude of industrial applications. However, the toxicity of certain metal-containing catalysts and diisocyanate reagents, as well as the non-renewability of many common multi-functional hydroxyl monomers, have led to the investigation of more environmentally-friendly and sustainable alternatives. Additionally, the use of non-biodegradable and non-recyclable polymers has led to astonishing accumulation of waste in the world’s oceans, prompting an increasing outcry from the public. The work presented in this dissertation focuses on replacing non-renewable starting materials such as metal-containing catalysts and multi-functional hydroxyl monomers with natural products or organically-derived reagents.
A synthetic methodology was developed that allows for the incorporation of carbohydrate-based natural products into functional PUs under mild conditions, employing relatively benign reagents, and resulting in nearly quantitative macrocycle formation as extensively verified using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-TOF MS). This work involved screening of conditions for PU synthesis using hexamethylene-1,6-di(p-nitrophenyl)carbamate, a diazabicyclo[5.4.0]undec-7-ene (DBU) organobase, and the bio-sourced diol, methyl 4,6-O-benzylidene-α-(D)-glucopyranoside. Unlike many previous PU syntheses involving dicarbamates, this system achieved polymerization under relatively mild conditions, e.g., attaining a molar mass of up to ca. 9 kDa in 8 h at 40 °C at ambient pressure. This chemistry has potential applicability to a wide range of di(p-nitrophenyl)carbamates and diols that should create broad interest in the PU community for sustainability and hazard mitigation.
Additionally, this dissertation examines the unusual selectivity for cyclization that the glucopyranoside dihydroxyl monomer imparts on the system using Raman spectroscopy and molecular modelling. A structural difference was indicated by Raman spectroscopy but its identity remains inconclusive by molecular modelling. Third, multiple synthetic schemes were attempted towards an antibiofouling polyurethane using a capsaicinoid molecule as a sensory deterrent for marine and microbial antibiofouling. The conjugation via the carbonate linkage appears most promising but all synthetic routes were complicated by several factors and thus remain incomplete. Lastly, a solvatochromic carbonate was realized, and molecular modeling indicates that it undergoes electron transfer in polar, heteroatom-containing solvents giving rise to a solvent-induced “redoxochromic” effect that has potential applicability in radical-mediated reactions and polymerizations. | en |
