Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene
- ORNL
- University of Tennessee, Knoxville (UTK)
Chain-end functionalization of living poly(styryl)lithium using 1-(3-bromopropyl)-2,2,5,5-tetramethyl-1-aza-2,5-disilacyclo-pentane (BTDP) to generate primary amine end-functionalized polystyrene was investigated using high vacuum anionic polymerization techniques. 13C NMR spectroscopy and Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) were used to evaluate polymer end-groups and demonstrated that quantitative amine functionalized polymer was attained under appropriate reaction conditions. In general, the polymerization of styrene was conducted in benzene and the end-capping reaction was performed by adding tetrahydrofuran (THF) to the reaction prior to the addition of BTDP in THF at room temperature. Results indicated that approximately 20% THF by volume is required to obtain 100% end-capping free from side reactions. When too little or no THF was present, side reactions such as lithium halogen exchange followed by Wurtz coupling resulted in unfunctionalized head-to-head dimer as well as other byproducts. Modeling and simulation of the solvent effects using hybrid methods (the so-called QM/MM method) suggest that THF effectively dissociated the anionic chain-end aggregation, thereby resulting in the desired primary amine functionalized polymer. Molecular dynamics (MD) simulations were conducted to develop an understanding of the physics of counterions involved in the end-functionalization process.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1040732
- Journal Information:
- Polymer Chemistry, Vol. 2, Issue 11; ISSN 1759-9954
- Country of Publication:
- United States
- Language:
- English
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