Degenerative transfer polymerization method

VAc has been successfully polymerized via controlled/ living radical polymerization techniques including nitroxide-mediated polymerization, organometallic-mediated polymerization, iodine-degenerative transfer polymerization, reversible radical addition-fragmentation chain transfer polymerization, and atom transfer radical polymerization. These methods can be used to prepare well-defined various polymer architectures based on PVAc and poly(vinyl alcohol). The copper halide/t is an active ATRP catalyst for VAc, providing a facile synthesis of PVAc and its block copolymers. Further developments of this catalyst will be the improvements of catalytic efficiency and polymerization control. 

Terminally brominated PE as PE macroinitiator can be produced by other methods. It has been reported that vinyl terminated PE produced by a bis(phenoxy-imine)metal complex and MAO catalyst system (Mn = 1800, Mw/Mn = 1.70) was converted to terminally 2-bromoisobutyrate PE through the addition reaction of 2-bromoisobutyric acid to the vinyl chain end. Polyethylene-Wodc-poly( -bulyl acrylate) (PE-fo-PnBA) from terminally brominated PE by ATRP procedure has also been produced [68]. It was reported that degenerative transfer coordination polymerization with an iron complex can be used to prepare terminally brominated PE as a macroinitiator [69]. A Zn-terminated PE prepared using an iron complex and diethylzinc,... 

The cleavage of C l bond can be achieved by various methods [149-151]. However, from well-chosen monomers, two main ways have been developed in order to control telomerization from alkyl iodides Iodine Transfer Polymerization (FTP) and degenerative transfer. 

The fifty chapters submitted for publication in the ACS Symposium series could not fit into one volume and therefore we decided to split them into two volumes. In order to balance the size of each volume we did not divide the chapters into volumes related to mechanisms and materials but rather to those related to atom transfer radical polymerization (ATRP) and to other controlled/living radical polymerization methods reversible-addition fragmentation transfer (RAFT) and other degenerative transfer techniques, as well as stable free radical pol5mierizations (SFRP) including nitroxide mediated polymerization (NMP) and organometallic mediated radical polymerization (OMRP). 

In a recent study, Yu et al. combined the palladium-diimine-catalyzed metallocene polymerization and ATRP to synthesize polyethylene-h-polystyrene and polyethylene-h-poly(butyl acrylate) [165]. A relatively new coordination olefin polymerization method - degenerative transfer coordination polymerization - was recently combined with ATRP to prepare block and graft copolymers with linear polyethylene segments [166-169]. 

Reversible addition-fragmentation chain transfer (RAET polymerization is the third LRP method which has been developed to a relatively mature state since its first demonstration in 1998 [51] (Scheme 13.9). RAET is a specialized case of the degenerative transfer LRP mechanism in which the controlling agent (X) is a thiocarbonylthio molecule (e.g. dithio esters, dithiocarbamates, trithiocarbonates). 

Figure 11.32 Reaction scheme of controlled free-radical polymerization, based on degenerative chain transfer, of butyl acrylate (R = C4H9COO-) in the presence of secondary alkyl iodide (R = CH3CH(Ph)-, X = 1) as the degenerative transfer agent. The latter alone does not initiate polymerization. (Drawn following the method of Matyjaszewski et al., 1995.)...

Control by degenerative transfer (DT) involves perhaps the smallest change from a eonventional free radical process of all the controlled/living polymerization proeesses developed to date. A recent review of various methods of telomer synthesis [180] diseusses the different types of transfer agents and monomers and the contribution of the teehniques of telomerization to CRP (includes discussion of iodine transfer polymerization, RAFT, and macromolecular design through interchange of xanthates (MADIX)) [181,182]. 

Destarac, M., et al. (2001). Synthesis method for polymers by controlled radical polymerization with xanthates. In PCT bit. Appl. WO 0142312, Rhodia Chimie, Fr., 46 pp. Gaynor, S. G., Wang, J.-S., and Matyjaszewski, K. (1995). Controlled radical polymerization by degenerative transfer elfect of the structure of the transfer agent. Macromolecules, 28(24) 8051-8056. 

Another method of control is based on degenerative chain transfer polymerization (DT), the term originally introduced a few years earlier. It is discussed in detail by Moad et... 

Polymerization, recently reviewed" ) only pertains to the use of cobalt and is not spedfic for the reversible deactivation mechanism vide infra). The term OMRP covets aU metals. The use of this aaonym was initially limited to the reversible deactivation mechanism outlined in Figure 1. However, it has recently been shown that organometallic compoimds may also act as transfer agents for the controlled radical polymerization that follows the degenerative transfer prindple, as outlined later in Section 3.11.4. In this chapter, both these two controlled polymerization methods, which may in certain cases interplay, will be outlined. When addressing each specific mechanism, an additional qualifier will be added to the acronym, OMRP-RT for reversible termination and OMRP-DT for degenerative transfer, whereas the OMRP term will be used in a more general situation. 

Substantial effort has been directed toward the control of vinyl acetate (VAc) radical polymerization using living radical polymerization (LRP) methods, including atom transfer radical polymerization, degenerative transfer through alkyl iodide,dialkyl tellurium, trithiocarbonate, xanthate, and cobalt acetylacetonate The focus of... 

These methods are based on the idea of establishing equilibrium between the active and dormant species in solution phase. In particular, the methods include three major techniques called stable free-radical polymerization (SFRP), atom transfer radical polymerization (ATRP), and the degenerative chain transfer technique (DCTT) [17]. Although such syntheses pose significant technical problems, these difficulties have all been successively overcome in the last few years. Nevertheless, the procedure of preparation of the resulting copolymers remains somewhat complicated. 

CoMRP In aqueous dispersed systems Similar to TeRP, CoMRP follows the dual mechanism of reversible termination and degenerative chain transfer. It was applied in suspension and in miniemulsion for the polymerization of VAc and allowed wdl-defined polymers to he prepared at low temperamre (0-30 C) with quite a fast rate The miniemulsion process yidded latexes writh small partides (diameter of approximately lOOnm) and good stahUity. CoMRP is one of the best methods (heside RAIT using a xanthate as a chain transfer agent) to produce poly(vinyl acetate) with conttolled molar mass, and its successful implementation to an aqueous dispersed system is an important step. 

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