(616h) Kinetic Analysis of Degradable Resins in Digital Light Processing

Photocurable resins, typically consisting of a combination of multi-functional monomers and oligomers, a photoinitiator, and an optical absorber, are formulated for a wide array of applications in 3D printing. The complex reactions that occur during the formation of often highly cross-linked networks in 3D printing has seen minimal investigation, as the available experimental methods to analyze the final 3D printed specimen are limited when they will not readily go into solvent. By utilizing a methacrylated anhydride oligomer in a resin system that was engineered for 3D printing, a unique opportunity exists to provide insight into the initiation, propagation, and termination steps in free-radical polymerization by analyzing the linear-degradation products of the 3D printed photopolymer resin upon exposure to water. Ongoing efforts include the utilization of a specific synthesis protocol for the production of surface-eroding methacrylated polyanhydride oligomers that readily degrade in the presence of water. Addition of particular constituents in the reaction mechanism at different stages influences the physiochemical behavior of the oligomer in unique environments by incorporating different degrees of hydrophobicity into the the oligomer backbone while maintaining functionalized end groups that will later react to form cross-linked networks during the 3D-printing process.

Fabrication of a frugal microfluidic apparatus has been developed to access the kinetics of surface-eroding polymer degradation using a series of tunable, simple, and low cost processing steps. Theoretical models are being developed to aid in quantifying the surface-erosion data that is gathered by image analysis of the degradation device. In-depth analysis of the degradation rates and mechanisms with a novel and adaptable flow apparatus are being coupled with previously explored methods of analyzing linear-degradation products of multi-functional monomers to give insight into the complex chemical mechanisms that occur while printing resin formulations in specific environments as well as the effect of specific elements within the underlying molecular architecture. Preliminary data provides reproducible, material-saving, and time-efficient methods to measure the effects of the molecular architecture, printing parameters, and post-curing procedures on the mechanical properties of 3D printed acrylic-based degradable resins.