QUASI-"LIVING" GRIGNARD METATHESIS POLYMERIZATION FOR THE SYNTHESIS OF REGIOREGULAR POLY(3- ALKYLTHIOPHENES)

charged with 2,5-dibromo-3-hexylthiophene (1.6 g, 5 mmol), pdimethoxybenzene (internal standard) (0.3 g) and anhydrous THF (165 mL). A 2M solution of t-butyl magnesium chloride (2.5 mL, 5 mmol) in diethyl ether (Et2O) was added via a deoxygenated syringe, and the reaction mixture was gently refluxed for 2 hrs. After the consumption of 2,5-dibromo-3hexylthiophene the reaction mixture was cooled at 20-22 o C. The concentration of unreacted 2-bromo-5-chloromagnesium-3-hexylthiophene was determined by GC-MS (more than 90% of monomer was consumed in 2 hrs). Ni(dppp)Cl2 (0.05 g, 0.1 mmol) was added as a suspension in 1 mL of anhydrous THF. The polymerization continued for 3 hrs before addition of 2bromo-5-chloromagnesium-3-dodecylthiophene . Analyses. GC-MS analysis was performed on a Hewlett-Packard Agilent 6890-5973 GC-MS workstation. The GC column was a Hewlett-Packard fused silica capillary column cross-linked with 5% phenylmethyl siloxane. Helium was the carrier gas (1 mL/min). GPC measurements were performed on a Waters 2690 separations module apparatus and a Waters 2487 dual λ absorbance detector with chloroform as the eluent (flow rate 1 mL/min, 35 oC, λ=254 nm) with a series of three Styragel columns (10 4 , 500, 100 A; Polymer Standard Services). Toluene was used as internal standard and calibration based on polystyrene standards was applied for determination of molecular