| Abstract: | The morphological features of composite latex particles predominantly develop during the polymerization process and depend upon a significant number of variables. In this study, we have concentrated on the relative polarities of the two polymers in the particles and the rate at which we added the monomers during semibatch reactions containing the seed polymer latex. Our particular interest was to develop data that could reveal the extent of polymer phase separation as a function of the amount of monomer fed, and to characterize the morphology resulting from it. While TEM is the most common analytical technique employed, we show in this paper that modulated temperature DSC can generate data that allows us to follow the phase separation process as the monomer feed progresses. By considering the possibilities of having “phases” within the particles of pure polymer, homogeneously mixed (but nonequilibrium) polymers, gradient and interfacial polymer, we have been able to quite successfully simulate the DSC data. This results in quantitative estimates of the relative amounts of these “phases” and their polymer compositions. Combining these results with TEM photos showing the spatial characteristics of the morphology, we can achieve a much greater understanding of the physical structure of the composite latex particles. In many cases we find that phase separation is far from complete at the end of the reaction process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2790–2806, 2005 |
