GOALI: Connecting the Dots: Using Radical-formation Control to Achieve Desired EB-initiated Polymer Properties

A joint academic-industrial partnership between the University of Iowa and ebeam Technologies (eT) is proposed to study fundamental science of electron beam curing of polymers. The work could eliminate the need for free-radical initiators in polymerization, help understand the mechanism of the initiation step by ebeam, and could lead to more uniform curing profiles.

Electron-beam (EB) curing offers a faster, lower-power, and solvent-free means of polymerizing inks, films, coatings, and adhesives when compared to thermal drying and curing processes. The goal of this research project is to advance EB-curing technologies by developing structure-processing property relationships that incorporate the fundamental knowledge of how chemical structure influences radical formation and reactivity.

This understanding will also enable the extension of EB-curing technologies to a wider range of applications, including high-performance materials for the automotive and aerospace industries and low-migration materials for the food and medical product industries.

The following research topics will be pursued: (1) correlation of the radiation yield with monomer structure, (2) comparison of property development in EB- and UV-cured systems having equal radical concentration, (3) control of crosslink density through monomer structure and composition, and (4) minimization of migration through monomer structure and composition. Kinetic rates and radical concentrations will be measured using spectroscopic techniques to obtain monomer initiation efficiencies.

Molecular weight distributions (for linear polymers), crosslink density (for polymer networks), and mechanical properties will be measured using gel permeation chromatography and dynamic mechanical analysis to demonstrate the impact of initiation mechanism, monomer structures, and process parameters on polymer physical properties. Gas chromatography/mass spectrometry will be used to identify and quantify leachable materials and their diffusion coefficients for ultra-low-migration systems.

Development of advanced relationships between EB kinetics and the resulting polymer properties may provide a level of understanding of EB-cured systems significantly beyond what is now available. In addition to training graduate students in an industrially-relevant area of study, outreach activities to K-12 and undergraduate students in STEM are planned based on polymer demonstrations incorporating project results.

Special emphasis will be placed on recruiting underrepresented female and minority students to participate in this research project.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.