To perform on-line monitoring of the absolute weight-averaged mass, Mw, of the polymers produced in a polymerization reaction, refractometer (RI), ultraviolet absorbance (UV), and time-dependent static light scattering (TDSLS) detectors were placed in series, and a diluted stream of reactant solution was made to flow through them. The technique allows rapid determination of time-dependent reaction "signatures" and end-product masses. Hence the effects of changing reaction conditions such as reactant concentrations, temperature, and initiators can be quickly assessed. Such a technique is expected to be of wide utility in characterizing polymerization reactions, both on the laboratory scale, where new polymers are synthesized and conditions optimized, as well as on the industrial scale, where on-line quality control can be performed. For stepwise reactions, the RI and TDSLS detectors are sufficient for determination of M w, whereas for free radical reactions, the polymer concentration must be measured in order to obtain the traditionally defined Mw (i.e. without monomer taken into consideration). The latter was achieved for poly(vinyl pyrrolidinone) polymerization by measuring the monomer concentration with the UV detector. As a further measure of characterization, a single capillary viscometer was also placed in series with the other instruments. This allowed the reduced viscosity to be monitored simultaneously.

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Using a programmable mixing pump, light scattering flow chamber, refractive index detector, and single capillary viscometer, the batch (unfractionated) characterization of polymers in solution has been automated. Three different schemes to produce polymer concentration gradients were used, and values for weight average mass M w , root mean square radius of gyration ͗S 2 ͘ 1/ 2 , second virial coefficient A 2 , and intrinsic viscosity [] were determined for a broad distribution sample of poly(vinyl pyrrolidone) (PVP) and a narrow fraction of poly(ethylene oxide) (PEO). High concentration experiments on the PVP also allowed determination of the third virial coefficient A 3 . The method has several advantages over traditional manual methods in terms of accuracy, sample preparation, and amount of labor required.