Polychloroalkane initiators in copper-catalyzed atom transfer radical polymerization of (meth)acrylates

A series of polychloroalkanes CClnR4-n (n = 2, 3, or 4) was tested as initi ators for atom transfer radical polymerization (ATRP) of methyl methacrylat e (MMA) and methyl acrylate (MA) using CuCl/2,2'-bipyridine as the catalyst . 2,2-Dichloropropane and 2,2-dichloroethanol initiate the ATRP of MMA very slowly. 1,1,1-Trichloroalkanes, RCCl3, are good initiators. For all the R groups tested, the number-average molecular weight (M) over bar(n) increase s with conversion and polydispersities are low (1.1 < (M) over bar(w)/(M) o ver bar(n) < 1.3). The initiator efficiency factor increases with electroph ilicity of the initiating radical (0.7 < f < 1). CCl4 is a multifunctional initiator and the final (M) over bar n values are lower than targeted. This is explained by the generation of new polymer chains occurring once the th ird active site is creased per chain. ATRP of MA initiated by CCl3CH2CF2Cl or CCl3C8H17 results in polymers with (M) over bar(n) values predetermined by the Delta[M]/[Initiator](0) ratio (f close to 1) and narrow molecular we ight distributions ((M) over bar(w)/(M) over bar(n) < 1.3 at high conversio n). The polymerization is much slower than that of MMA, but can be consider ably accelerated by use of Cu(0) metal while maintaining an excellent contr ol over molecular weights and polydispersities.