Polyolefins have dominated global polymer production for the past 60 years, revolutionizing fields of medicine, construction, travel, packaging, and many more. However, with steadily increasing polyolefin production each year and traditionally long polyethylene (PE) and polypropylene degradation times, estimated on the order of 500 years or more, a massive challenge arises with accumulating plastic waste. While the end-of-life of polyolefins previously manufactured must be addressed, incorporation of sustainability and circularity into future commodity plastic design at the molecular level offers an opportunity to decrease their negative effects on the environment going forward. Herein, several approaches are described which aim to address the need for polymeric materials while introducing a sustainable approach to their design, either through incorporation of biosynthesized polymers or degradable units. In the first project, polymer blends of two biodegradable polymers were studied, and compared to the same blends containing a graft copolymer compatibilizer comprised of the two homopolymer counterparts. The compatibilized blends were expected to have superior mechanical performance to the uncompatibilized blend and potentially offer industrially relevant benefits. While this was not achieved, valuable insight into the polymer blend interactions were gained. The idea of compatibilizing polymer blends was further explored with blends of PE and a cellulose derivative with the aid of a custom ABA triblock compatibilizing agent. It was discovered that the compatibilizer reinforced the polymer blend by providing mechanical strength at the cost of flexibility. To approach sustainability from a different perspective, several segmented copolymer series based on telechelic PE oligomers were then synthesized and analyzed. The segmented systems exhibited similar structure to high density PE (HDPE), retained similar mechanical and thermal properties to commercial HDPE, but contained degradable units throughout the polymer backbone. Several fundamental principles were explored through the segmented and chain-extended polyolefin architecture, including the influence of reactive linkage (amide vs. ester), random vs. alternating segment structure, and PE segment molecular weight. The effects of tailoring polymer structure on thermal, mechanical, and morphological properties are described herein. The relationships established from these experiments may further guide future polymer design and contribute toward more sustainable polyolefin manufacturing.

The following thesis documents a two-fold approach to investigate challenges pertaining to water purification, first through a meta-analysis of ionic liquid toxicity, then through experimentation aimed at developing water pre-treatment membranes. Ionic liquids (ILs) are salts with low melting points, typically liquid at room temperature. Several extraordinary physical attributes, e.g. low viscosity, high conductivity, low to no vapor pressure, etc., and seemingly unlimited combinations available, have pushed IL research to the forefront of many research fronts. Concerns are raised as ionic liquids are rushed into commercial production without sufficient environmental regulation. Research has shown that the chemicals are in fact toxic, yet have developed a reputation for being “green” chemicals due to select physical attributes and applications. The meta-analysis discussed focuses on industry perception of ionic liquid toxicity through a patent review, and considers toxicity of ILs comparatively against other chemical families with well-established toxicity. The meta-analysis revealed that the total patent literature pertaining to ILs (n=3358) resulted in 112 patents that addressed the toxicity of ILs, and notably few (n=17) patents defined ILs as toxic, representing only 0.51% of the evaluated body of work on intellectual property claims. Additionally, toxicity of ionic liquids is comparable to that of other chemical families.
The objective of the experimentation was to explore the effect of crosslinker chain length on the morphology of nanofiber mats. Specifically, poly(vinyl alcohol (PVA) was electrospun into nanofiber mats and poly(ethylene) glycol bis(carboxylic acid) (PEG diacid) was used as the crosslinking agent. As-spun fibers had average fiber diameter of 70 ± 30 nm with an average pore size of 0.10 ± 0.16 μm^2. The fiber diameter for the mats crosslinked with the shorter PEG diacid (Mn = 250) increased to 110 ± 40 nm with an average pore size of 0.11 ± 0.04 μm^2. The mats crosslinked with the longer PEG diacid (Mn = 600) had fiber diameters of 180 ± 10 nm with an average pore size 0.01 ± 0.02 μm^2.