Engineering Science and Materials Commons^™

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …

Structure And Energetics Of Nanoparticles And Ionomer Films In Fuel Cell Catalyst Layers, Qianping He

Doctoral Dissertations

Improving the durability and utilization efficiency of the platinum-on-carbon (Pt/C) catalyst is of vital importance to the commercialization of the polymer electrolyte membrane fuel cell (PEMFC). This body of work provides molecular level insights to aid the fulfillment of this goal. Chapter 1 describes the use of molecular dynamics (MD) simulation in an effort to understand the Pt/C degradation issue from the nano-adhesion point of view. The roles of catalyst nanoparticle size, shape, Pt/C surface oxidation and the extent of ionomer film hydration are investigated to study their effects on nano-particle adhesion. It is found that the adhesion force strengthens …