Heterogeneous time dependent static light scattering

Measurements of light scattering from flowing heterogeneous solutions conta ining coexisting populations of colloids and polymers are presented. By app ropriate recognition of scattering peaks produced by individual colloid par ticles and recovery of the baseline scattering due to the polymer populatio n, the colloid particle number density can be monitored in real time while the polymer population is characterized absolutely according to weight-aver age molecular weight M-w and z-average mean square radius of gyration < S-2 >(z). Either or both populations may also be evolving in time, so that the technique is termed "heterogeneous time dependent static light scattering" (HTDSLS). The essential notions of the technique are presented, and then th e feasibility of the simultaneous measurements is first demonstrated by an equilibrium characterization of poly(vinylpyrrolidone) (PVP) "contaminated" by known concentrations of 2 mu m latex spheres. The time dependent capabi lities are then demonstrated by monitoring the growth of Escherichia coli b acteria in a solution containing PVP. It is expected that HTDSLS will find many applications, such as in biotechnology reactors, biomedical assays, an d polymer reactors where gels or crystallites are produced in addition to p olymer chains.