Sequence-Controlled Vinyl Polymers by Transition Metal-Catalyzed Step-Growth and Living Radical Polymerizations

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Sequence-Controlled Vinyl Polymers by Transition Metal-Catalyzed Step-Growth and Living Radical Polymerizations Kotaro Satoh and Masami Kamigaito Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603, Japan ABSTRACT The metal-catalyzed step-growth radical polymerization was achieved to enable two systems for preparing tailored polymeric structures, i.e., sequence-regulated vinyl copolymer and periodically-functionalized polymer. The former is a novel strategy for preparing sequenceregulated vinyl copolymers by step-polymerization of sequence-regulated vinyl oligomers prepared from common vinyl monomers as building blocks. The later deals the simultaneous chain- and step-growth radical polymerization, which resulted in the polymers with periodic functional groups. INTRODUCTION The metal-catalyzed atom transfer radical addition (ATRA or Kharasch reaction) is a highly efficient carbon–carbon bond forming radical reaction [1]. Nowadays, this chemistry is widely applied to radical addition polymerizations of vinyl monomers that developed into the metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP) and to open a new era of precision polymer synthesis [2-4]. Recently, we have found a new class of transition metal-catalyzed step-growth radical polymerization of the designed monomer, which has a reactive carbon–halogen bond and an unconjugated carbon–carbon double bond in a single molecule [5]. This reaction is also based on the metal-mediated radical addition similarly to the metal-catalyzed controlled/living radical polymerization, which is triggered by the activation and de-activation of the carbon-halogen bond derived from an initiator molecule. Whereas one halogen atom survives at the end terminal of each polymer chain in the living polymerization, the intermolecular step-growth polymerization occurs to form carbon-carbon backbone chain with inactive carbon-halogen pendants. This conceptually new radical polymerization will provide various types of linear polymers, including the equivalents of sequence-regulated vinyl copolymers from designed monomers. In the present paper, the step-growth radical polymerization was evolved into the two systems for preparing tailored polymeric structures, i.e., sequence-regulated vinyl copolymer and periodically-functionalized polymer. The former is a novel strategy for preparing sequenceregulated vinyl copolymers by step-polymerization of sequence-regulated vinyl oligomers prepared from common vinyl monomers as building blocks, such as styrene, acrylate, acrylamide, acrylonitrile, and vinyl chloride [6,7]. In the later part, the simultaneous chain- and step-growth radical polymerization was investigated by copolymerizing step-growth monomers with common vinyl monomers, i.e., the step-polymerization was simultaneously compatibilized

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with the metal-catalyzed atom transfer radical polymerization, which resulted in the polymers with periodic functional moieties [8,9]. EXPERIMENTAL DETAILS Material

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