(140a) Superior Emulsion Formation in Microchannel Architecture

The characteristics and performance of emulsified products are the result of a combination of the chemical formulation and the processing technology employed. Traditionally, emulsions are formed under high shear conditions using static mixers, ultrasound devices, homogenizers, or rotor/stator mixers. The shear field, temperature history, and composition profiles during the process are key factors in the final form of the emulsion. Emulsion compositions and processing conditions are typically over-designed to ensure product requirements are met. This formulation and processing approach leads to the use, and often overuse, of expensive surfactants, overshearing sensitive materials, high energy consumption, and can ultimately lead to less than optimum product performance.

The microchannel emulsification process adds discontinuous phase droplets to the continuous phase, one droplet at a time, in multiple parallel channels. The resulting droplet size distribution is controlled by a variety of processing conditions, including substrate pore size, stream pressures and temperature. The microchannel approach permits precise control of mixing energy, mixing time, and heating/cooling energy, all of which stay constant during process scale-up. This tight process control offers many advantages. First, the droplets are formed one at a time by pushing the discontinuous phase through a specially designed substrate. This allows for high shear at the wall, but low bulk shear to avoid damaging the sometimes fragile emulsion components. Second, tight droplet size distribution possible in microchannel architecture enhances mixture stability. Third, in-line heating and cooling permits gentle reagent heating as well as rapid product quenching, which helps produce very stable emulsions.

Examples will demonstrate the innovative approach to emulsification allowed by the microchannel architecture. Furthermore, the paper will discuss its potential use to explore processing conditions to enable previously inaccessible product formulations with shear-sensitive materials and controlled drop size distribution. Microchannel emulsification could be beneficial for a wide range of industrial and consumer applications, including pharmaceuticals, food products, adhesives, and personal care products.