Date of Award
Spring 2024
Document Type
Open Access Dissertation
Department
Chemistry and Biochemistry
First Advisor
Chuanbing Tang
Second Advisor
Ting Ge
Abstract
Plastics have become an integral part of everyday life, from household care to aerospace applications, polymers are involved in every industry. Most of these polymeric materials are derived from petroleum feedstocks which have deleterious effects on our environment. The production of petrochemicals has led to an increase in greenhouse gases and microplastic pollution which have accelerated climate change. My research focuses on utilizing existing biomasses to improve the plastic economy’s circularity. This work develops new materials from bio-based polymers such as lignin and soybean oil. Raw lignin suffers from inherently weak mechanical properties, poor solubility, processability, and molecular structure ambiguity. To solve these problems several routes are explored.
In Chapter 2 lignin is chemically modified to create a reprocessable thermoset network that can undergo chemical degradation. The modification of lignin and the synthesis of a new type of crosslinker are detailed and analyzed. The resulting thermosets are explored mechanically showing an improvement in strength and tunable flexibility. The crosslinkers are then chemically degraded under basic and acidic conditions to show the labile silyl ether bonds. Finally, the degraded products are remodified and reformed indicating the reprocessability of these materials. In Chapter 3, the applications of these materials are explored in adhesive formulations. Different blends of hardeners are combined with modified lignin under various weight percentages. The lap-shear strength of these formulations is then tested across a diverse number of substrates. The adhesion is then examined under prolonged loads and real-world applications are provided. The adhesion was then explored in wet conditions and then the adhesion mechanism was investigated using synthetic experiments and computational molecular dynamic simulations. The resulting adhesives displayed excellent adhesion and contained a large amount of biomass.
The second part of this thesis focuses on cyclic polymers. In chapter 5, the synthesis and characterization of semi-crystalline ring polymers is detailed. The mechanical strength of different crosslinked cyclic polymers is measured and then compared to their linear analogues. The difference in mechanical strength based off the architecture is rationalized using x-ray and dynamic mechanical analysis. The difference in tensile strength is shown to arise from a difference in crystallization Finally, in the last chapter, the summary and conclusions of my dissertation are given. Furthermore, an outlook and future work in sustainable chemistry is provided as well as a possible research direction on cyclic polymers.
Rights
© 2024, Yishayah Bension
Recommended Citation
Bension, Y.(2024). The Study of Biomass Based Polymers and Cyclic Polymers. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/7679