He is a mid-career chemist employed at Polaroid Corporation in New Bedford, MA. Dr. Eustace's fields of interest and expertise include photographic and imaging science and technology, electrochemistry and solid state science, manufacturing and statistical science. Daniel began his career in 1974 with Exxon Corporation. Daniel earned his Ph. D. in physical chemistry from Brandeis University in 1974 and received a B. A. in chemistry from the State University of New York at Buffalo in 1970.

Daniel volunteers with Habitat for Humanity. He has served in the Massachusetts National Guard from 1970-76. Dan's grandfather, Frank Eustace emigrated from Hamilton, Ontario in 1923 with his wife Mary Theresa (Maud) Eustace. Daniel’s great-great-great grandfather John Eustace reportedly came to Hamilton, Ontario from Dublin, Ireland.