Synthesis and characterization of peptide/amino acid based materials and solvent-free UV curable coatings
The research presented in this dissertation involves two distinct areas, polymers for biomaterials and coatings for enhanced oxygen and carbon dioxide barrier properties. The biomaterials section involves the synthesis of bis-glutamic-2,5-diketopiperazine diesters for condensation polymerizations (Chapter II), and methacrylate derivatives based on natural materials for coating and gel applications (Chapter III). Amino acid based methacrylate derivatives were synthesized that had very fast photopolymerization rates both alone and with commercial monomers. Temperature dependent crosslinking was observed, and solution cast, photocured, and thermally cured coatings gave excellent adhesion to poly(ethylene terephthalate) (PET) and glass surfaces. Chapter IV includes research involving the surface modification of PET for binding bioactive ligands. Fibrous bundles of PET were treated with diamines or an amino-alcohol to create a tether between the surface and a reactive group. The reactive alcohol or amine groups could be further modified by ring-opening succinic anhydride to give carboxylic acid groups on the end of the tethers. Intact functional binding of an antigen, antibody, or enzyme was achieved. The second section involves the investigation of various (α-hydroxymethyl)acrylates as coatings for barrier improvement. This work includes mechanistic investigations into the photopolymerization behavior of RHMA derivatives (Chapter V). RHMA derivatives were photopolymerized with various multifunctional acrylates and methacrylates. The effect of crosslinker type and degree of functionality on photopolymerization rates and conversions was investigated. The research presented in Chapter VI describes the barrier properties of RHMA coatings. A new high-barrier coating for PET was developed along with the process for preform dipping and cure prior to blow molding into bottles. The UV curable coating gives excellent barrier improvement when brush coated onto PET biaxially oriented thin films. Also, blown bottle side-wails from coated PET preforms show 2-3 times improvement over uncoated side-walls. The final chapter of this dissertation involved the synthesis of a hyperbranched poly(ether-alcohol) under basic conditions. Previously, oxetane monomers were reported to polymerize only under cationic conditions. Chapter VII describes the ring-opening of 3-ethyl-3-hydroxymethyloxetane using an alkoxide initiator. Hyperbranched materials were obtained, and the presence of cyclic endgroups was confirmed by MALDI-TOF analysis.