Semicontinuous emulsion copolymerization to obtain styrene-methyl acrylate copolymers with predetermined chemical composition distributions

Four types of emulsion radical copolymn. processes were applied to produce various styrene-Me acrylate copolymer (I) latexes. The first was batch emulsion copolymn. In the second method (a), monomer-starved semicontinuous emulsion copolymn., a monomer mixt. of const. compn. was fed to the reactor at a const. rate. Sufficiently low addn. rates led to homogeneous copolymers. In the third method (b), optimal addn. rate profiles were used to produce homogeneous emulsion I in relatively short times. The profiles were detd. in a semiempirical way and applied to three different I compns. There was also an attempt to det. an addn. rate profile to produce a heterogeneous emulsion I with predetd. heterogeneity, i.e., a I of which the chem. compn. distribution did not consist of one narrow peak, as with homogeneous I, but had a predetd. broadness profile. Strategies a and b were used to produce homogeneous emulsion I with varying fractions of styrene. Strategy b was also used to demonstrate the influence of the monomer ratio on the reaction speed. The advantage of this method was that the monomer ratio was const. over the whole conversion range in the latex particles. HPLC was used to det. the homogeneity/heterogeneity of the I produced, and proved to be invaluable in detg. the optimal addn. rate profil