Mechanism and size control

Antonietti et al. [ 1 ] and Wu [2] have reported on the size control of the polymerized microemulsion in the system styrene, di-isopropenylbenzene (cross-linker), cetyltrimethylammo-niumchloride (CTMACI) or a similar surfactant, and water. According to a simple model developed by Wu [2] the resulting latex size is a function of the fleet ratio s = mjmyi with ms and /wm, the masses of surfactant and monomer respectively, given by 

Macromolecular Systems Microscopic Interactions and Macroscopic Properties Deutsche Forschungsgemeinschaft (DFG) 

Copyright 2000 WILEY-VCH Verlag GmbH, Weinheim. ISBN 978-3-527-27726-1 

Whereas Eq. 1 is almost perfectly confirmed by the experimental data of Antonietti et al. and Wu, the present data do not follow Eq. 1 and show much more scatter than literature results (Fig. 14.1). Variation of the ionic strength of the continuous phase, of the reaction temperature, of the total monomer content, and of the concentration of crosslinking agent has essentially no effect on the resulting microemulsion. 

As shown in Fig. 14.2 differences, however, were observed for different initiators, e. g. AIBN, redox system (K2S2O8/K2S2O5), and dibenzylketone. Although much effort was taken to improve the reproducibility and size control we could never reproduce the literature data for AIBN initiation particularly at small S. We presently cannot offer a satisfactory explanation for this discrepancy. 

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Fei, X., Zhao, H., Zhang, B., Cao, L., Yu, M., Zhou, J., Yu, L., 2015. Microencapsulation mechanism and size control of fragrance microcapsules with melamine resin shell. Colloids and Surfaces A Physicochemical and Engineering Aspects 469, 300—306. 

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