August 27, 2018
(PIB) is a workhorse polymer that is found in a multitude of products,
ranging from chewing gum, to tires, to engine oil and gasoline
additives. Although commercially produced in large quantities since the
1940s, PIB chemistry was a mystery - scientists weren't sure how the
reaction mechanism that creates the polymer happens at the molecular
level, which limited further potential.
However, a collaboration between the University of Pittsburgh's Swanson
School of Engineering and Wickliffe, Ohio-based Lubrizol Corporation has
unlocked the secrets of PIB's reaction mechanism. The group's findings
were published this month in the journal ACS Catalysis (DOI:
Reaction mechanism showing a
proton transfer from the superacid catalyst to isobutylene. This is the
first step in the PIB polymerization process.
Principal investigator is Karl Johnson, the William Kepler Whiteford
Professor in the Swanson School's Department of Chemical & Petroleum
Engineering. Funding for the research was provided by Lubrizol, which in
2014 established a $1.2 million strategic partnership with the
Department and Swanson School to jumpstart research innovation that also
offers opportunities for undergraduates to participate.
is an incredibly versatile polymer. It can have many different
properties depending on how it is made. There are many different
'recipes' for making PIB, each employing different catalysts and
reaction conditions, but it turns out that no one really knows what is
happening at the molecular level. Finding out what is going on is
important because it is harder to control a process that you don't
Solving this catalytic puzzle is of interest to Lubrizol, which
specializes in ingredients and additives for polymer-based products.
Utilizing the University's Center for Research Computing to analyze the
molecular processes, the Pitt/Lubrizol group found that the assumed
reaction mechanism was not correct and that initiation of the reaction
requires a "superacid" catalyst.
"These findings provide fundamental insight into the PIB reaction
mechanism that could potentially be used to design different catalysts
and to control the reaction - and hence, the potential range of products
- in ways that are currently not possible." Dr. Johnson said. "This
project shows the value of creating academic/industrial partnerships to
pursue research that might not be possible if pursued independently."