CONTROL OF CALCIUM-CARBONATE PARTICLE-SIZE AND SHAPE BY PRECIPITATIONFROM CTAB ALCOHOL/HEXADECANE MIXTURES/

When used as a precipitation media, emulsified mixtures of cetyltrimet hylammonium bromide/n-butanol (E), hexadecane (O) and water (W), contr ols the size and shape of calcium carbonate particles. Monodisperse 2- micron spherical-calcite particles were obtained in a water-rich regio n of the mixture, while 2-micron rhombohedral-calcite particles with a n aspect ratio near one were obtained in the middle region of the mixt ure. Replacing n-butanol with i-butanol led to consistent formation of monodisperse spherical particles, while using n-propanol in place of iz-butanol limited the number of spherical particles produced in the w ater-rich region.