β Scribed by Ke Min; Wojciech Jakubowski; Krzysztof Matyjaszewski
No coin nor oath required. For personal study only.
Summary: The recently developed initiation system, activators generated by electron transfer (AGET), is used in atom transfer radical polymerization (ATRP) in the presence of a limited amount of air. Ascorbic acid and tin(II) 2βethylhexanoate are used as reducing agents in miniemulsion and bulk, respectively. An excess of reducing agent consumes the oxygen present in the system and, therefore, provides a deoxygenated environment for ATRP. ATRP of butyl acrylate is successfully carried out in miniemulsion and in the presence of air. During polymerization the radical concentration remains constant. The polymerization reaches over 60% monomer conversion after 6 h, which results in polymers with a predetermined molecular weight $\overline M _{\rm n}$β=β14β000 gβΒ·βmol^β1^ and a low polydispersity ($\overline M _{\rm w} /\overline M _{\rm n}$β=β1.23). AGET ATRP of styrene is also successful in bulk in the presence of air, as evidenced by linear semiβlogarithmic kinetics, which leads to polystyrene with an $\overline M _{\rm n}$ of 13β400 gβΒ·βmol^β1^ and a low polydispersity index ($\overline M _{\rm w} /\overline M _{\rm n}$β=β1.14).
Appearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).
magnified imageAppearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).
π SIMILAR VOLUMES
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