Syndiospecific styrene polymerization with CpTiCl₃/MAO: Effects of the order of reactant addition on polymerization and polymer properties

Abstract

Syndiospecific styrene (St) polymerization, catalyzed by the CpTiCl 3 /methylaluminoxane (MAO) system, was investigated using two different activation procedures. The polymerization parameters included polymerization time, temperature (ϳ25-100°C), ratio of [Al]/[Ti] (ϳ100 -1000), and catalyst precursor concentration (ϳ0.5-10.0 ϫ 10 Ϫ4 mol Ti/L). It was found that adding reactants in the order of (CpTiCl 3 ϩ MAO) ϩ St (Injection of Styrene mode) gave much higher monomer conversion rates, higher weight-average molecular weights, and narrower molecular weight distributions than for the (St ϩ MAO) ϩ CpTiCl 3 (Injection of Catalyst mode). The former also yielded significantly higher syndiotacticity fractions. Differential scanning calorimetry measurements showed multiple peaks exhibiting polymorphism in crystalline syndiotactic polystyrene samples.

Syndiotactic Polystyrene Nanofibrils in Silica Nanotube Reactors: Understanding of Synthesis with Ultrahigh Molecular Weight

“…The synthesized nanofibrils were analyzed by 13 C NMR spectroscopy (Figure a). The characteristic peak at 145.5 ppm confirms that the polymer fibrils obtained are syndiotactic polystyrene, and the entire spectrum matches very well with those of sPS in previous reports. , The syndiotacticity of the polymer fibrils measured by the 13 C NMR is 100% (i.e., single peak at 44.3 ppm in the 43.0−47.0 ppm range). Molecular weight and molecular weight distribution (MWD) are important polymer parameters that have a significant impact on the polymer's physical, mechanical, and rheological properties.…”

Kinetics of Styrene Polymerization to Syndiotactic Polystyrene over Metallocene Catalyst on Flat Surface, Silica Nanotube Reactors and Porous Silica Particles

“…The syndiotacticity of sPS measured by extraction with boiling methyl ethyl ketone (MEK) or 13 C NMR spectroscopy was 95−100% for the tested catalysts. The sPS analysis data of syndiotacticity and molecular weight distribution with Cp*Ti(OCH 3 ) 3 /MAO catalyst system have been reported previously in detail elsewhere. ,, …”

“…The sPS analysis data of syndiotacticity and molecular weight distribution with Cp*Ti(OCH 3 ) 3 /MAO catalyst system have been reported previously in detail elsewhere. 7,27,28 ' RESULTS AND DISCUSSION Polymer Morphology. sPS is known to grow in nanofibrillar morphology with silica-supported metallocene catalysts.…”

Derivatisation of boryl substituted titanium half-sandwich complexes – Molecular structures of [Ti{(η5-C5H4)B(NiPr2)N(H)tBu}Cl2(NMe2)] and [{TiCl2(μ-{OB(NHMe2)-η5-C5H4})}2-μ-O]

“…Styrene polymerisation experiments were performed in 100 mL Schlenk bottles following a modified literature procedure [27]. Specific amounts of toluene, a stock Table 4 Summary of the crystal data and details of data collection and refinement for compounds 10 and 12…”