Kinetic Studies on Star Polymerization of Styrene, MA and MMA Using New Three and Four Arm Chain Transfer Agents (CTAs): The Role of R-Group Structure Present in the CTA on RAFT Polymerization

Autor:	Raghavachari Dhamodharan, Mukundamurthy Kannan
Rok vydání:	2011
Předmět:	Chain-transfer agents four arm star polymers Methyl acrylates Methyl methacrylates Reversible addition fragmentation chain transfer three arm star polymers Esters Free radical polymerization Free radicals Living polymerization Mass spectrometry Polymers Polymethyl methacrylates Polystyrenes Stars Styrene Acrylic monomers Materials science Polymers and Plastics Chain transfer General Chemistry chemistry.chemical_compound Living free-radical polymerization chemistry Polymerization Polymer chemistry Materials Chemistry Ceramics and Composites Reversible addition−fragmentation chain-transfer polymerization Polystyrene Methyl methacrylate
Zdroj:	Journal of Macromolecular Science, Part A. 48:722-736
ISSN:	1520-5738 1060-1325
Popis:	Polystyrene, poly(methylacrylate) and poly(methyl methacrylate) four and three-arm stars were synthesized by Reversible Addition Fragmentation chain-Transfer (RAFT) polymerization by using two new dithioester-derived chain transfer agents [CTA or R-S-(C = S)Z]), CTA-1 and CTA-2. CTA-1 is a four arm CTA while CTA-2 is a three-arm CTA. These were easily synthesized from commercially available reagents and were characterized by spectroscopic techniques such as 1H-NMR, 13C-NMR, IR and mass spectrometry. It is demonstrated that the two new CTAs enable the growth of arms away from the core (i.e., core first approach). An attempt has been made to study the effect of the structure of the R-group, which is present as the core in the CTA, on the polymerization, by analyzing the detailed kinetics. This study suggests that CTA-2, with a benzylic R group, enables the controlled star polymerization of styrene while CTA-1, with a R group similar in structure to the propagating radical derived from the polymerization of methyl acrylate (MA), enables the controlled polymerization of MA although to a lesser extent. This study also reveals that the temperature of free radical initiated RAFT (star) polymerization should be chosen in such a way that it is a compromise between reasonable rate of homolysis of the initiator and the CTA (R-group). � Taylor & Francis Group, LLC.
Databáze:	OpenAIRE
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