Hexenyl functionalized poly(dimethylsiloxane) and methacryloyloxy functionalized poly(methyl methacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) macromonomers were synthesized using living polymerization techniques. The PDMS macromonomers were prepared by the anionic ring-opening polymerization of hexamethylcyclotrisiloxane followed by termination with a functionalized chlorosilane derivative. The methacryloyloxy functionalized PMMA macromonomers were prepared using group transfer polymerization with a protected hydroxyl functional initiator. The molar masses of the macromonomers ranged from 1000 g/mol up to 20000 g/mol with narrow molar mass distributions, less than 1.1, and high percent functionalities. The hexenyl functionalized PDMS macromonomers, having a range of molar masses, were statistically terpolymerized with l-butene and sulfur dioxide to yield poly(l-butene sulfone)-g-PDMS copolymers of various chemical compositions up to 20 wt% PDMS. The bulk and surface phase morphologies were investigated using DSC, TEM, XPS, and water contact angle measurements. The graft copolymer was shown to be an excellent resist for electron beam lithography with a 44u4C/cm4 sensitivity and a 33:1 etch ratio relative to a cross linked novolac resin. The 7000 g/mol methacryloyloxy functionalized PMMA macromonomers were copolymerized anionically with MMA to yield PMMA-g-PMMA polymers having absolute molar mass distributions less than 1.1 containing from 5 wt% to 40 wt% of the macromonomer at constant overall molar mass of 250000 g/mol. The graft polymers were utilized as model homopolymers exhibiting long chain branching. The methacryloyloxy functionalized PDMS macromonomers were free radically and anionically copolymerized with MMA to yield PMMA-g-PDMS copolymers. The graft copolymers were fractionated and their chemical composition distributions were determined as a function of copolymerization mechanism. In addition, preliminary studies were started using aluminum-27 NMR to study several different aluminum porphyrins based on (5,10,15,20-tetraphenyl) porphine (TPPH₂) . The aluminum porphyrins were formed by reacting trimethylaluminum with TPPH₂ to yield TPPAIMe. The resulting aluminum porphyrin was modified by adding a stoichiometric amount of various carboxylic acids to form aluminum porphyrin carboxylates that had varying steric and electronic effects on the macrocycle. / Ph. D.

The synthesis of poly (butyl vinyl ether) and poly (butyl vinyl ether 2-chloroethyl vinyl ether) random copolymers was accomplished through the use of the aluminum hydrogen sulfate catalyst (AHS). In this system, AHS acts as a heterogeneous catalyst in the cationic polymerization of vinyl alkyl ethers. Highly isotactic polymers (greater than 70%) have been prepared and characterized by IH and 13C NMR. DSC characterization of poly(butyl vinyl ether) also reveals that these polymers are semicrystalline. Gel permeation chromatography characterization and intrinsic viscosity data of poly(butyl vinyl ether), and poly{butyl vinyl ether-2-chloroethyl vinyl ether) homopolymers and copolymers indicate fairly narrow polydispersities, and very high molecular weights. A study of this copolymerization by lH NMR revealed that the 2-chloroethyl ether monomer was being incorporated along the chain with the greater percentage of the 2-chloroethyl vinyl ether monomer near the chain ends. Reactions on the pendent chlorine group are currently under investigation in our laboratories. It is anticipated that a range of pendent functional groups can be obtained. / Master of Science

The thesis outlines the development of novel cationic zinc complexes for application in lactide polymerization catalysis. These complexes were characterized spectroscopically and crystallographically, and where appropriate their efficacy as catalysts for the polymerization of lactide was evaluated. The strongly donating, neutral chelating ligands employed in this study were prepared by installation of either one or two phosphinimine donors on a dibenzofuran backbone. An efficient synthetic methodology was then developed for the synthesis of cationic complexes of the formula [LZnE+][BAr4-], wherein E = C2H5, CH3, Ph, C6F5, OAc, OC6F5, or methyl-(D,L)-lactate, and AR = Ph, C6F5, or m-(CF3)2-C6H3. Only the cationic zinc-lactate species were found to be highly active polymerization catalysts. Tuning of the steric and electronic properties of the ligand resulted in the discovery of zinc-lactate systems that promote rapid and well-controlled polymerization of lactide under mild conditions, marking the first well-defined cationic metal catalysts to do so. / xxiv, 254 leaves : ill. ; 29 cm + 1 CD-ROM

Indiana University-Purdue University Indianapolis (IUPUI) / As liver disease becomes more prevalent, the development of an in vitro culture system to study disease progression and its repair mechanisms is essential. Typically, 2D cultures are used to investigate liver cell (e.g., hepatocyte) function in vitro; however, hepatocytes lose function rapidly when they were isolated from the liver. This has promoted researchers to develop 3D scaffolds to recreate the natural microenvironment of hepatic cells. For example, gelatin-based hydrogels have been increasingly used to promote cell fate processes in 3D. Most gelatin-based systems require the use of physical gelation or non-specific chemical crosslinking. Both of these methods yield gelatin hydrogels with highly interdependent material properties (e.g., bioactivity and matrix stiffness). The purpose of this thesis research was to prepare modularly crosslinked gelatin-based hydrogels for studying the influence of independent matrix properties on hepatic cell fate in 3D. The first objective was to establish tunable gelatin-based thiol-norbornene hydrogels and to demonstrate that the mechanical and biological properties of gelatin hydrogels can be independently adjusted. Furthermore, norbornene and heparin dual-functionalized gelatin (i.e., GelNB-Hep) was prepared and used to sequester and slowly release hepatocyte growth factor (HGF). The second objective was to investigate the viability and functions of hepatocytes encapsulated in gelatin-based hydrogels. Hepatocellular carcinoma cells, Huh7, were used as a model cell type to demonstrate the cytocompatibility of the system. The properties of GelNB hydrogels were modularly tuned to systematically evaluate the effects of matrix properties on cell viability and functions, including CYP3A4 activity and urea secretion. The last objective was to examine the effect of heparin immobilization on hepatocyte viability and functions. The conjugation of heparin onto GelNB led to suppressed Huh7 cell metabolic activity and improved hepatocellular functions. This hybrid hydrogel system should provide a promising 3D cell culture platform for studying cell fate processes.