Molar masses were determined by size exclusion chromatography (SEC). The apparatus was equipped with a 1260 infinity pump (Agilent Technologies), a 1260 infinity autosampler (Agilent Technologies), a 1260 infinity UV photodiode array detector (Agilent Technologies), and a 1260 infinity RI detector (Agilent Technologies). The stationary phase was composed of 2 PSS-SDV Linear M column and a precolumn at 40 °C. The mobile phase was THF at 1 mL.min -1 .