| dc.description.abstract | This thesis is composed of two studies. The first study investigates the interfacial properties of alkylated graphene oxide nanosheets using Langmuir-Blodgett techniques. The second study examines the direct ink write (DIW) additive manufacturing of linear polycaprolactone diacrylate shape memory polymers with generated porosity for ultimate applications in bone scaffolds. Below are summaries of each study.
In recent years, there has been an increasing interest in developing functionalized graphene oxide nanosheets as stabilizers for pickering emulsion systems. Alkylated graphene oxide nanosheets can be used to stabilize pickering emulsion systems, and are notable for the broad range of com-positions that can be used (oil/water, oil/oil, and ionic liquid/oil). The purpose of this study is to understand the various parameters that influence the surface interactions of these nanosheets, in complement to the emulsion systems. Langmuir Blodgett experiments are conducted to identify the impact of alkyl chain lengths used for functionalizations, the effects of the solvent used for deposition, and the pH and ionic concentration of the liquid subphase. The interfacial phase transformations involved are compared to the maximum surface pressure and the onset of surface potential measurements while trying to determine the effect of various experimental parameters in-volved. The solvent used for sample dispersion as well as the alkyl chain length used for the sample functionalization both impact the interfacial nanosheet interactions. Emulsions being a two-phase system, different modifications to the trough medium were also generated through varying pH and subphase salt concentration to gather insights on how this would impact the behavior of different nanosheets on the interface. These variables were not identified to significantly impact nanosheet interactions.
The efficiency of bone scaffold implants in curing bone defects is dependent on their suitable fit, osteoinductivity, degradation properties, and biocompatibility. In the second part of the study, direct ink write (DIW) additive manufacturing is employed to print linear polycaprolactone diacrylate shape memory polymers with generated porosity for ultimate applications in bone scaffolds. The ink generated for printing is rheologically modified through the addition of sodium chloride (NaCl) particles, which are sacrificial and removed via washing with water thus generating micropores in the structures. The use of printing gives additional flexibility in the construction of macropores through print design. Salt particles with a size of less than 38 microns are utilized to induce shear thinning characteristics in the polymer solution, which is then printed and cured using UV radiation. After the printing and curing phases, the salt particles are subsequently removed to create porosity. The printed structures with porous features and shape memory capability are subjected to further analysis to investigate their compositional, thermal, mechanical, and shape memory properties. This study focuses on the direct ink writing (DIW) process of these polymers and examines the ink composition to understand the effects of different factors on the properties of the printed objects. Several steps are taken to achieve desirable features, and a comprehensive analysis is carried out to investigate how each parameter impacts the properties of the printed objects. | |
