Kinetic investigations of polymerization of methyl methacrylate with zirconocenes

Abstract

The polymerization of methyl methacrylate (MMA) in toluene with Cp2ZrMe2 (1) – Ph3C+B(C6F5)4− (4) as initiating system was kinetically investigated. This system can be regarded as a combination of the systems described by Collins and Soga. Only if the ratio of 1/4 was larger than 1, monomer conversions of more than 99% and polymers with number‐average molecular weights higher than 200 000 and polydispersities 1.5–1.6 were obtained. From a kinetic analysis of time‐conversion curves using the software package Predici, it can be deduced that the mechanism is consistent with that proposed by Collins et al. However, the mechanism has to be extended by incorporating a first‐order termination reaction of the active species. Rate coefficients of all elementary reactions were determined from time‐conversion curves. The kinetic investigations were accompanied by ab initio calculations, which support the assumed kinetic model.

Molecular weight distribution modeling in low-density polyethylene polymerization; impact of scission mechanisms in the case of CSTR

“…However, implementation of this scission mechanism leads to the complete disappearing of the bimodality, as is visible et al (1997). PREDICI J uses a Galerkin h-p FEM, and it has been shown as an e cient numerical tool in various applications in polymerization reaction engineering (Bandermann et al, 2000;Iedema et al, 2000Iedema et al, , 2003Hutchinson, 2001). Our discussion of scission will be involved with several issues.…”

Polymerization of Methyl Methacrylate with Chloro Zirconocene Enolates

“…b) Theoretical values were calculated using the reaction system in Scheme 3 and the rate coefficients in Table 3. a) For reaction conditions, see Table 1 and 2. b) Determined by 13 C NMR spectroscopy. c) Calculated according to Bernoulli Statistics with R r ¼ 0.78.…”

“…We have performed a series of kinetic studies with the systems, Cp 2 ZrMe 2 /Ph 3 CB(C 6 F 5 ) 4 [13] as well as Cp 2 ZrMe[OC(OMe) CMe 2 ]/Cp 2 ZrMe þ , [14] that clearly indicate that a bimetallic mechanism is decisive for chain growth in MMA polymerization when methyl zirconocenes with unsubstituted cyclopentadienyl ligands are used to initiate the reaction. This is in agreement with the results of our theoretical calculations.…”

“…L/mol L/(min Á mol) L/(min Á mol) L/mol 1 and 4 2.7 Â 10 À3 9.6 Â 10 3 8.0 Â 10 1 4.1 Â 10 À3 2 and 4 2.5 Â 10 À3 1.3 Â 10 4 2.2 Â 10 1 5.1 Â 10 À3 5 and 6 [13] 6.9 Â 10 À3 8.4 Â 10 4 3.0 Â 10 3 2.9 Â 10 À3 a) Reaction conditions: solvent toluene, reaction temperature 0 8C.…”

“…[13] The exchange of the methyl group by a chlorine ligand has the effect that all steps, with the exception of the monomolecular termination reaction, are clearly slowed down. This is true in particular for the separation step of the bimetallic complex.…”