A round robin study for the characterization of latex particle morphology—multiple analytical techniques to probe specific structural features

Determining the detailed morphology of composite latex particles in a confident manner is often very challenging and sometimes seemingly impossible. This paper reports on the details of an interlaboratory study, a so-called ‘round robin’ study, designed to determine the complete details of the particle structure of a particular styrene–acrylic copolymer latex system. Independent organizations received portions of the same composite latex and each performed several analytical measurements of the characteristics of the latex particles. Techniques included SEM, TEM, AFM, NMR, DSC, MFFT, GPC, CHDF and QELS. Each analytical test was performed by at least two independent laboratories using the protocols adopted by the individual organizations. Subsequently representatives from each of the six laboratories participated in a workshop to contribute their data, assess the results from all of the information developed, and to draw collective conclusions regarding the detailed structure of the particles. Complete morphology details must include the overall particle shape, the composition of its outermost region, and the internal structure. Multiple, complimentary sets of analytical data were necessary to confidently determine the particle structure, even for the well phase separated latex particles studied here.