Semibatch copolymer latexes

FIGURE 6.14 Proposed scheme for control of copolymer composition and average molecular weights in semibatch methyl methacrylate/butyl acrylate emulsion copolymerizations. Reprinted (adapted) with permission from Vieira RAM, Sayer C, Lima EL, Pinto JC. Closed-loop composition and molecular weight control of a copolymer latex using near-infrared spectroscopy. Ind Eng Chem Res 2002 41 2915-2930. 2002 American Chemical Society. 

In the semibatch experiments, the particle size distributions of the final latexes were affected by the residual surfactant in the seed latex, which tended to facilitate homogeneous nucleation during the entire feed period. The monomer feedrate determined the polymerization rate and had little effect on copolymer composition. The polymer compositions for the runs with different monomer feeding modes tended to be identical at very low feedrate. 

The difunctional derivative DIAMA has also been used in emulsion polymerization (Figure 17) 30,231 enabling a significant reduction in particle size and narrower distribution compared to latexes prepared using monoflinctional BlocBuilder MA . Polystyrene-I -poly(n-butyl acrylate)-Zi-polystyrene triblock copolymers were made using the difunctional alkoxyamine, and allowed nanostmctured particles to be formed upon internal phase separation. A refined semibatch process shortened overall process time compared to earlier efforts. ... 

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