Polymer-assisted control of particle morphology and particle size of zinc oxide precipitated from aqueous solution

Water-soluble poly(ethylene oxide-block-methacrylic acid) (P(EO-b-MAA)) and poly(ethylene oxide-block-styrene sulfonic acid) (P(EO-b-SSH)) diblock copolymers were used to control the particle morphologies, sizes and size distributions of zinc oxide precipitated from aqueous solution. With P(EO-b-MAA) copolymers, hexagonal prismatic particles form. Their sizes and size distributions depend on the degrees of polymerization of the blocks. With P(EO-b-SSH) copolymers, the particle shape reminds one of a "stack of pancakes". These samples have narrow size distributions, regardless of the degrees of polymerization of the P(EO-b-SSH) copolymers. All crystals have a central grain boundary assigned to twinning. There is evidence for P(EO-b-MAA) copolymer adsorption onto the basal planes of the zinc oxide particles, whereas with P(EO-b-SSH) also an adsorption onto the side faces seems possible. The polymers are incorporated to some extent in the crystals and the amount of the polymer incorporated depends on the initial polymer concentration of the reaction solution.