Molecular weight distribution polydisperse

Size exclusion chromatography coupled to static light scattering (SEC-MALLs) Molecular weight, molecular weight distribution. Polydispersity. Radius of gyration and distribution solution conformation and flexibility. Method of choice for moleciflar weight work. [4]... 

The first single-site metal catalyst which was shown to homogeneously catalyze the coupling of epoxides and C02 was (tpp)AlCl (tpp = tetraphenylporphyrin) in the presence of a quaternary organic salt or triphenylphosphine [20]. Although this catalytic system was extremely slow at ambient temperature, copolymers from ethylene oxide, PO, and CHO and C02 were obtained that possessed very narrow molecular weight distributions (polydispersity = 1.06-1.14). The low reactivity of... 

The polymerization of norbornene, Eq. (19), is stopped by cooling the reaction mixture to room temperature. The active polymer 11 can be stored for long periods of time. Heating 11 to temperatures above 65 °C in the presence of monomer causes renewed chain propagation. The subsequent addition of different cyclic olefins, such as endo- and exo-dicyclopentadiene, benzonorbomadiene and 6-methylbenzonorbornadiene resulted in the formation of well-defined AB- and ABA-type block copolymers, Eq. (21) [38]. Triblock copolymers 13 with narrow molecular weight distributions (polydispersity = 1.14) were prepared. Thus, the living character enables the preparation of new uniform block copolymers of predictable composition, microstructure and molecular weight. 

The molecular weight (Mw) and the molecular weight distribution (polydispersity Mw/M ) of the terpolymers were determined by gel-permeation chromatography with a Waters instrument equipped with UV and RI detectors and using Waters Ultrastyragel columns. The samples were measured at 30 °C in chloroform containing 0.1 vol % triethylamine as the mobile phase with a flow rate of 11/min. 

M = number average molecular weight, determined by GPC M IM = molecular weight distribution (polydispersity). 

Schork FJ, Smulders W. On the molecular weight distribution polydispersity of continuous living-radical polymerization. J Appl Polym Sci 2004 92 539-542. 

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