10/6/2026 Jackson Brunner
Professor Phil Geil passed away at the age of 95 in September 2026 following multiple health challenges. He was a foundational figure in polymer science and worked hard as a leader in Illinois materials science and engineering, serving as a champion for future generations of scientists.
Written by Jackson Brunner
Phil Geil, professor emeritus of materials science and engineering at The Grainger College of Engineering and a leader in the polymer science community, passed on Sept. 9, 2026, at age 95 after battling multiple health challenges.
Geil began his career at DuPont in the 1950s and moved to what is now Case Western Reserve University in 1963. He joined the materials faculty at the University of Illinois Urbana-Champaign in 1979, recruited to help build a polymer science program on a campus that had almost none. He studied how polymers form crystalline and solid-state structure, and his 1963 book "Polymer Single Crystals" is still considered a foundational text. He edited the Journal of Macromolecular Science and was a fellow of the American Physical Society. From 2000 to 2008, he served as associate head of the department before retiring as professor emeritus.
"Phil's impact on this department is hard to overstate," said Department Head Paul Braun. "He helped establish polymer science at Illinois, and the cross-college interdisciplinary polymer group he founded helped motivate the merger that created our department. He was a gifted researcher and a dedicated educator, and generations of students and colleagues benefited from his commitment to this community."
G. Ronald and Margaret H. Morris Professor Ken Schweizer, a faculty member who joined the materials department in 1991, overlapped with Geil for about 15 years. Schweizer said Geil's early work at Illinois was foundational.
"Polymers are really important, but there was almost nothing on polymers on campus when he came here,” Schweizer recalled. “The engineering college made a strategic decision that they needed to start hiring polymer people. And Phil was the senior person who was a leader in physical polymer science that they attracted from Case Western Reserve University.”
Geil shaped how the department taught and shared research. He helped develop new polymer courses and created the Polymer Seminar in the early 1990s — a near-weekly forum where graduate students, postdocs and faculty presented their work.
"He was the leader, the organizer and the person who conceived that," Schweizer said. “The seminar's model of cross-talk between research areas eventually spread across the department and now has evolved into broad-based soft and hard materials student-oriented seminars.”
Schweizer said Geil's contributions went well beyond his own research.
"Phil was always thinking about improving the department as a whole in both education and organization. He was very impactful, including his leadership accomplishments as one of the very first associate heads of materials science and engineering, and the replacement of a formal division structure (metals, ceramics, electronic, polymer materials) by the present one that is unified across specialties."
When Geil became associate head of the department, he served as a resource for the materials department's leadership.
"He was a knowledge repository of so much of the history (and pre-history) of the department, with broad and deep knowledge of academia which greatly informed the founding of the materials science department in 1987 and the first head who was from industry," Schweizer said. “He was a very positive influence in trying to make important changes happen in the department in a way that the faculty would buy into.”
In 2005, Illinois materials science and engineering established the Geil Scholarship Fund in recognition of the late professor’s desire to ensure the success of future generations of scientists. It continues to be awarded to this day as deserving students are identified.
The department's thoughts are with Professor Geil’s family during this difficult time.
Illinois Grainger Engineering Affiliations
Paul V. Braun is department head of Materials Science and Engineering. He holds the Grainger Distinguished Chair in Engineering appointment.
Ken Schweizer is a professor of materials science and engineering in the Department of Materials Science and Engineering. He holds the G. Ronald and Margaret H. Morris Professor appointment.