Development of supermolecular structure in polystyrene latexes

The development of supermolecular structure in polystyrene latex particles was investigated by small‐angle neutron scattering (SANS). Seed latexes of deuterated polystyrene were swollen with an equal mole‐% of protonated styrene monomer, equilibrated, and polymerized to complete conversion. The scattering patterns reflect the extent of supermolecular structure development inside the particle. The data were analyzed by separating the Debye single‐chain and spherical scattering form factors. The extent of segregation was found to depend on the relative size of the chains compared with that of the particle, going through a maximum at the ratio M w / D of about 0.1, where D w represents the weight‐average diameter of the latex particle. When the chain dimensions are relatively very small, uniform molecular mixing is obtained. The best model for the segregated system is a graduated core‐shell supermolecular structure.