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Title: Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene

Abstract

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.

Authors:
 [1];  [1];  [1];  [1];  [1];  [2]
  1. ORNL
  2. University of Tennessee, Knoxville (UTK)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Center for Nanophase Materials Sciences
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1040732
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Polymer Chemistry
Additional Journal Information:
Journal Volume: 2; Journal Issue: 11; Journal ID: ISSN 1759-9954
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AMINES; BENZENE; DESORPTION; DIELECTRIC MATERIALS; DIMERS; HALOGENS; IONIZATION; LASERS; LITHIUM; MASS SPECTROSCOPY; PHYSICS; POLYMERIZATION; POLYMERS; POLYSTYRENE; SIMULATION; SOLVENTS; SPECTROSCOPY; STYRENE; TETRAHYDROFURAN

Citation Formats

Messman, Jamie M, Goswami, Monojoy, Pickel, Deanna L, Uhrig, David, Sumpter, Bobby G, and Mays, Jimmy. Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene. United States: N. p., 2011. Web. doi:10.1039/c1py00226k.
Messman, Jamie M, Goswami, Monojoy, Pickel, Deanna L, Uhrig, David, Sumpter, Bobby G, & Mays, Jimmy. Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene. United States. doi:10.1039/c1py00226k.
Messman, Jamie M, Goswami, Monojoy, Pickel, Deanna L, Uhrig, David, Sumpter, Bobby G, and Mays, Jimmy. Sat . "Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene". United States. doi:10.1039/c1py00226k.
@article{osti_1040732,
title = {Combatting Ionic Aggregation using Dielectric Forces Combining Modeling/Simulation and Experimental Results to Explain End-capping of Primary Amine Functionalized Polystyrene},
author = {Messman, Jamie M and Goswami, Monojoy and Pickel, Deanna L and Uhrig, David and Sumpter, Bobby G and Mays, Jimmy},
abstractNote = {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.},
doi = {10.1039/c1py00226k},
journal = {Polymer Chemistry},
issn = {1759-9954},
number = 11,
volume = 2,
place = {United States},
year = {2011},
month = {1}
}