Discipline: Chemistry and Chemical Sciences
Subcategory: Materials Science
Princess M. Walker - Ball State University
Co-Author(s): Dr. Courtney Jenkins, Ball State University
60 million tons of elemental sulfur are produced each year from crude oil in the petroleum refining process. Inverse vulcanization was created to utilize the abundance of elemental sulfur by reacting it with another monomer to form functional polymers. Modification of these polysulfides is a possible means to broaden the versatility of sulfur based polymers. Utilizing the inverse-vulcanization method, a 30:70 ratio of sulfur: divinylbenzene (DVB) were combined on a 5 g scale at 185°C for 1 hour to create poly(S-DVB). Next, maleimide was grafted onto poly(S-DVB). This reaction occurs at 100°C at varied time trials ranging from 15 min to 48 hours. The reaction occurs because the S-S bonds within poly(S-DVB) cleave forming free radicals which bind to maleimide, incorporating it into the prepolymer. To aid miscibility between maleimide and poly(S-DVB), a small amount of dimethylformamide was added to the reaction. In an effort to make this reaction solvent free, a terpolymer was created by combining S8, DVB, and styrene in a 30:35:35 ratio. The addition of styrene allows the prepolymer to have a fluid consistency. Using poly(S-DVB-styrene) improved miscibility between maleimide and the prepolymer without the need for solvent. Polymers were characterized before and after completing the reaction by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). The NMR spectra revealed that as the reaction time increases, more maleimide is incorporated. Examining changes in the molecular weight revealed a substantial drop after 24 hours indicating that the backbone of the poly(S-DVB) is intact as the maleimide is incorporated initially, but the structure begins to degrade after 24 hours. Overall, we were able to create graft polymers by reacting maleimide using dynamic S bonds within polysulfides. The ability to modify these polymers demonstrates their versility in for future applications.
Funder Acknowledgement(s): Thanks to the NSF sponsored Indiana Louis Stokes Alliance Minority Program and the America Chemical Society Petroleum Research Fund.
Faculty Advisor: Dr. Courtney Jenkins, firstname.lastname@example.org
Role: Performed all experimental methods for this project.