by re precipitation from nh 4 oh solution conversions were determined by gravimetric analysis fecl 3 dialkyl ether complexes were prepared at room temperature just before the polymerization of ib in a glovebox dcm was added to fecl 3 which had been previously weighed and sealed in a 20 ml screw cap vial with a teflon seal next an equimolar amount of the appropriate ether was added drop wise via a syringe to the sealed vial containing the lewis acid while stirring to form a 1 0 m lewis acid ether complex solution number average molecular weight m n and polydispersities pdi of the polymers were obtained from size exclusion chromatography with universal calibration using a waters 717 plus autosampler a 515 hplc pump a 2410 differential refractometer a 2487 uv vis detector a minidawn multi angle laser light scattering malls detector measurement angles of 44 7 u00b0 90 0 u00b0 and 135 4 u00b0 from wyatt technology inc viscostar viscosity detector from wyatt technology inc and five ultrastyragel gpc columns connected in the following order 500 10 3 10 4 10 5 and 100 u00e5 refractive index ri was the concentration detector tetrahydrofuran was used as the eluent at a flow rate of 1 0 ml min at room temperature the results were processed by astra 5 4 software from wyatt technology inc proton nuclear magnetic resonance 1 h nmr spectra were recorded on a bruker 500 mhz spectrometer using cdcl 3 as solvent cambridge isotope laboratory inc the polyisobutene pib end group content was.