Daniel V. Krogstad

The choice of ionic liquid used in epoxy crosslinking influences not only the cure temperatures, but also the curing mechanisms and the glass transition temperatures of the resultant epoxy network.

Chitin/glucan complex (CGC) is a material which possesses a high potential for use in biomedical applications due to the favourable combination of antibacterial and immunostimulating activity of its constituents. However, its existing applications are limited by poor solubility in most solvents. This work is focused on processing and modifications of CGC isolated from Aspergillus niger using ionic liquids (IL). Two ILs have been employed: 1-ethyl-3-methylimidazolium acetate (EMIM-Ac), which is liquid at room temperature, and 1-butyl-3-methylimidazolium chloride (BMIM-Cl), which has a melting point of ~ 70°C. The modification of CGCs through facile and effective alkylation or grafting with polycaprolactone (PCL) significantly alter the mechanical properties without any undesired effects on cytotoxicity. In particular, PCL grafting leads to relatively elastic “soft” polysaccharide-based material with promising potential for medical applications. Processing and modification of CGC in IL also facilitated the formation of nanofibrils and related nano/micro porous materials. Additionally, all modifications, including deacetylation, facilitated the formation of wet spun fibers due to increased viscosity. The effect of two isolation methods of CGC, i.e. coagulation or phase separation induced by IL solidification, on the structure is highlighted as well.

Nanostructured epoxy composite resins have broad usage in adhesives, coatings, composites, and 3D printing. With these materials, careful control of the rheological properties is critical to ensuring that the properties meet their required performance targets. However, it can be difficult to accurately measure the rheological properties. In this work, we establish a method to develop a reliable pre-shear (PS) procedure to repeatably measure the apparent yield stress of the resins, which is critical to ensure the accurate understanding of the material behavior. The resins in this study consisted of an epoxy resin with nanoclay as a shear thinning agent, ionic liquid (1-ethyl-3-methylimidazolium dicyanamide) as a latent curing agent, and poly(ethylene oxide- b -propylene oxide- b -ethylene oxide) block copolymer (BCP) as a nanostructured component. We establish a methodology to evaluate the effectiveness of a pre-shear protocol and evaluate several methods to identify a pre-shear procedure that resulted in repeatable transient creep results on a rheometer. We identified that large amplitude oscillatory shear was the most effective method for these materials, and the optimal magnitude of the shear was dependent on the composition of the epoxy resins. Through the consistent application of this approach, we were able to use transient creep testing to identify the phase boundaries in the epoxy/BCP resins when the BCP micelles undergo an order-order transition from spherical to hexagonal micelles through changes in the yield stress of the material. This work adds to the new growing body of literature demonstrating the importance of establishing rigorous pre-shear conditions to improve the accuracy of structured yield stress fluids.

Biofeedstocks derived from living organisms or their byproducts have recently emerged as an environmentally benign complement to petroleum, diversifying energy production in the petroleum industry from sole dependence on crude oil while utilizing mostly existing petroleum infrastructure. However, biofeedstocks also bring challenges as they can cause distinct and potentially more severe corrosion in metal-based petroleum infrastructure than crude oils due to their higher molecular oxygen content and the presence of various organic acids. To effectively manage such corrosion, it is crucial to understand the corrosion mechanism, particularly the onset of local corrosion, as well as its relationship with the metallic microstructure. Here, using pentanoic acid─a typical degradation product and representative corrosion contributor from biofeedstocks─as the corrosive medium, we capture the real-time initiation and progression in corrosion of carbon steel lamella, which is a model petroleum infrastructure, at nanometer resolution. We correlate in situ liquid-phase transmission electron microscopy imaging of the corrosion process with ex situ characterization of grain size, orientation, and elemental distribution. Through this correlative, multimodal characterization, we identify the key microstructural features that significantly influence corrosion behavior: galvanic corrosion initiates corrosion, strain accelerates corrosion, and lattice orientation guides corrosion propagation. Contrary to aqueous corrosion, corrosion in pentanoic acid is not heavily influenced by the grain boundaries, with similar rates observed in coarse- and fine-grain lamellae. Our observations highlight the importance of intrinsic structural features of carbon steel and their impact on corrosion in biofeedstock-based organic acids, providing insights for potential corrosion mitigation.

An atmospheric-pressure, microwave-powered plasma process was used for surface cleaning and fabrication of Zr, Si, and Zr/Si-based bilayer conversion coatings on mild steel for corrosion protection. Si-based films were fabricated from a volatile organometallic precursor in the gas phase, and Zr-based films were produced by converting a solution-based precursor film. The fabricated coatings were characterized in terms of their morphology and composition, and their corrosion properties. Based on the results of electrochemical and corrosion weathering experiments, both Zr- and Si-based conversion coatings resulted in a significant decrease in the corrosion rate of the steel substrate. At the same time, the bilayer Zr/Si sample presented little improvement due to the presence of defects. Polarization measurements revealed that anodic inhibition was the main mechanism for corrosion protection in both Zr- and Si-based conversion coatings. The performance of the conversion coatings was further studied in an epoxy-polyamide paint system using the accelerated cyclic electrochemical technique, as well as salt fog corrosion testing. The results implied that both plasma cleaning of the surface (without any conversion film) and the presence of Zr-based conversion coating increased the low-frequency impedance of the system. However, in the presence of defects in the paint, the anodic inhibition by the Zr-based conversion layers played a key role in increasing the protectiveness and performance of the paint. The results of this study indicate that atmospheric-pressure plasmas can be a promising processing technology to fabricate conversion coatings on mild steel, minimizing chemical waste generated by solvent-based methods.

**Abstract Body** There are strong environmental, economic, and geopolitical drivers to supplement petroleum feedstocks with biological feedstock | ORAL

Small-angle X-ray scattering was utilized to investigate the morphological transition of glycerol monooleate under various compositions, temperatures, and additives such as water and fatty acids.