Probing the surface of polymer colloids by conductometric surfactant titration.
This work revisits the use of surfactant titrations for the characterization of latex particle surfaces. Experiments were performed to study the effect of comonomer composition and the effect of acid comonomers, and the technique is applied to the characterization of particle morphology in composite latices for several different systems. It is confirmed that the packing density of surfactant on a polymer surface is a linear function of copolymer composition. Inclusion of acid comonomers has the expected effect of decreasing the amount of surfactant adsorbed on the polymer surfaces. The usefulness of the technique in the determination of particle morphology is demonstrated, in particular toward the detection of thin layers of either seed or second-stage polymer on the particle surface which are not easily detected by other techniques such as transmission electron microscopy (TEM). Finally, it is shown that the use of acid comonomers in composite particles greatly reduces the usefulness of the surfactant titration technique for morphology characterization. A possible explanation for this effect is proposed.
Stubbs
Jeffrey M
JM
Nanostructured Polymers Research Center, University of New Hampshire, Durham, New Hampshire 03824, USA. jstubbs@cisunix.unh.edu
Roose
Patrice
P
De Doncker
Patrick
P
Sundberg
Donald C
DC