Methyl methacrylate iniferter polymerization

Qin SH, Qiu KY, Swift G et al. (1999) Living radical polymerization of methyl methacrylate with diethyl 2,3-dicyano-2,3-diphenylsuccinate as a thermal iniferter. J Polym Sd Part A Polym Chem 37 4610-4615... 

A polyhedron silsesquioxane ladder polymer containing polymerizable components was prepared in a three-step process to address this concern. The process initially entailed preparing the reversible addition-fragmentation transfer (RAFT) ladder iniferter, polysilsesquioxane dithiocarbamate. This intermediate was then polymerized with methyl methacrylate at ambient temperature by irradiating with ultraviolet (UV) light and poly(si Isesquioxane-g-methyl methacrylate) was obtained. 

The Inifer technique enables us to fulfil some requirements of polymer architecture even in some radical processes. An amplified form may be applied, the Iniferter variant, where the radical initiator simultaneously acts as a transfer and terminating agent. Otsu et al. used sulphides and disulphides (tetraethylthiuram disulphide, PhSSPh, Ph2S, PhCH2SSCH2Ph) [96] and carbamates (benzyl-A,A-diethyldithiocarbamate, p-xylylene-A,7V-diethyl-dithiocarbamate) [97] in the photopolymerization of methyl methacrylate and styrene, and phenylazotriphenylmethane in the polymerization of methyl methacrylate [98]. Living radical polymerizations yield polymers with defined end groups or the required block copolymers. 

The free radical polymerization of styrene initialized by iniferter is influenced by chemical binding of iniferter on the surface of the silica." This reaction is used for grafting the polymer onto the surface of the silica. A similar approach is used when carbon whisker is incorporated during the graft-polymerization of methyl methacrylate. Depending on how the whisker is prepared, surface conversion can be increased up to twelve times compared to a polymerization with no whisker present. The addition of graphite to the poly esterification reaction doubles the molecular weight of the polymer. ... 

RAFT polymerizations with this iniferter of iV-butyl acrylate and styrene yielded polymers with M. / Mn equal to 1.15 and 1.16 respectively. Polymerization of methyl methacrylate, however, yielded a polymer with a broad Mw/M ratio. On the other hand, polymerization in the presence of CuBr/TMPA by ATRP exclusively through the bromine chain ends yielded a polymer with narrow ratio [282],... 

The transfer coefficients of disulfides are extremely low for styrene and methyl methacrylate (see Table 4), but are close to one for the vinyl acetate polymerization. In general the xanthogens and thiurams have higher chain transfer ability, which has been attributed to the iniferter mechanism described above. Monosulfides have lower transfer coefficients in comparison to disulfides. This may refiect steric factors and the relative strength of the C—S bond, which is significantly stronger than the S—S bond. 

Thermal iniferters have been mainly used for the polymerization of methyl methacrylate. It was reported that polymerization of styrene with some thermal iniferters such as l,l,2,2-tetraphenyl-l,2-bis(phenoxy)ethane and tetraarylsc-cinonitriles proceeds via a dead-end polymerization mechanism, i.e., it does not follow living radical polymerization conditions. On the other hand, Jongh et al and Chernikova et al reported that some specially designed hexa-substituted-ethane derivatives can act as iniferters for styrene polymerization. 

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