Steric Stabilization of Nonaqueous Silicon Slips: I, Control of Particle Agglomeration and Packing

Abstract

The behavior of silicon powder dispersed in two nonaqueous processing media (benzene and trichloroethylene) with various adsorbed polymeric stabilizers (poly(styrene), poly‐(methyl methacrylate), and their copolymer) has been studied. Measured adsorption isotherms indicate that poly‐(methyl methacrylate) is adsorbed onto silicon in significantly greater amounts than poly(styrene) from both benzene and trichloroethylene. The adsorption phenomena are explained on the basis of the polymer‐medium interactions, the chemical structure of the polymers, and the surface chemistry of the silicon powder. In the case of the copolymer, the poly(methyl methacrylate) segments act as anchors to the silicon surface. The poly(styrene) segments project out into the medium and impart the necessary stabilizing action against particle agglomeration. Adsorption of poly(methyl methacrylate) and copolymer effectively controls particle agglomeration and enables the preparation of nonaqueous slips of silicon having stability similar to that which can be achieved in water. Control of particle agglomeration with this steric stabilization strategy results in compacts with improved particle packing as observed through sediment volume analysis.