Polymerization of acrylates and bulky methacrylates with the use of zirconocene precursors: Block copolymers with methyl methacrylate

Abstract

The polymerization behavior of cyclohexyl methacrylate and trimethylsilyloxyethyl methacrylate with the catalytic system Cp2ZrMe2/B(C6F5)3/ZnEt2 was examined. Block copolymers of these bulky methacrylates with methyl methacrylate (MMA), having high molecular weights and relatively narrow molecular weight distributions, were prepared. n‐Butyl acrylate and tert‐butyl acrylate were polymerized with various catalytic systems based on zirconocene complexes. These polymerizations seemed to proceed to a nonquantitative yield, producing polymers with high molecular weights and relatively low polydispersities. This behavior indicated the presence of termination reactions in the initiation step, which appeared to be faster than the propagation step. Block copolymers of these acrylates with MMA were synthesized with the catalytic system rac‐Et(Ind)2ZrMe2/[B(C6F5)4]−[Me2NHPh]+/ZnEt2, starting from the polymerization of MMA. The block copolymers produced were well defined in most cases, as indicated by size exclusion chromatography, NMR, and differential scanning calorimetry measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3337–3348, 2005

Coordination−Addition Polymerization and Kinetic Resolution of Methacrylamides by Chiral Metallocene Catalysts

“…There is increasing interest in the utilization of technologically important, single-site cationic group 4 metallocene catalysts, 1 which have been extensively investigated and successfully employed for the (co)polymerization of nonpolar vinyl monomers (R-olefins in particular), 2 for polymerizations of polar, functionalized vinyl monomers including methacrylates, acrylates, 40,[46][47][48][49] acrylamides, [50][51][52][53] and methyl vinyl ketone. 54 The polymerization of (meth)acrylates has also been studied computationally.…”

Synthesis of Neutral and Cationic Monocyclopentadienyl Tantalum Alkoxo Complexes and Polymerization of Methyl Methacrylate

“…Methyl methacrylate (MMA) polymerization with lanthanocenes and group 4 metallocene complexes has been widely explored in the last few years, ,− and recently, Chen and co-workers have extended this application to group 5 metallocene derivatives, , taking into account that they should show a more tolerant attitude toward this type of polar olefin than the more electron-deficient analogues of the lanthanides and group 4 metal derivatives. The catalysts based on [TaCp 2 Me 3 ]/2Al(C 6 F 5 ) 3 21 and [TaCp 2 (CH 2 )Me]/2Al(C 6 F 5 ) 3 22 systems gave syndiotactic PMMA of high molecular weight ( M n > 10 5 ), with narrower polydispersity for the alkylidene derivative [TaCp 2 (CH 2 )Me], both proceeding through a bimolecular anionic enolaluminate mechanism.…”

Chain Termination and Transfer Reactions in the Acrylate Polymerization by a Monometallic Chiral Zirconocenium Catalyst System

“…This process is not living, and analysis of the low-molecular-weight P( n -BA) by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI−TOF MS) led to two proposed modes of chain termination processes, the predominate of which involves the backbiting cyclization of the growing polymer chain. Most recently, a third report on the polymerization of acrylates ( t -BA and n -BA) by Hadjichristidis et al appeared, which employed Soga's three-component systems, including Cp 2 ZrMe 2 /B(C 6 F 5 ) 3 /ZnEt 2 , rac -(EBI)ZrMe 2 /B(C 6 F 5 ) 3 /ZnEt 2 , and rac -(EBI)ZrMe 2 /[HNMe 2 Ph][B(C 6 F 5 ) 4 ]/ZnEt 2 ; the polymer yields obtained from these polymerizations of n -BA and t -BA for 24 h did not exceed 30 and 32%, respectively, in any case, regardless of the catalyst system or polymerization conditions employed. The results from the above three reports clearly indicate the presence of considerable chain termination processes in the polymerization of α-proton-containing acrylates by group 4 metallocene complexes; this observation is in sharp contrast to the isoelectronic, neutral organolanthanide complexes such as (C 5 Me 5 ) 2 SmMe(THF) which mediate the living polymerization of alkyl acrylates .…”