ABSTRACT
Silicone emulsions produced by ionic polymerization of siloxane monomers in water have now been used for many years in commerce. Emulsions produced by such processes provide any, or a combination, of the following characteristics: improved production efficiency, reduced manufacturing cost, increased stability, and provision of the unique characteristics or properties of silicone to aqueous products. Those emulsions produced by the process of emulsion polymerization generally have a particle size less than about 200 nm. This is the “critical particle size for creaming” for polydimethylsiloxane particles in aqueous emulsion. Such emulsions will not exhibit creaming and would not need remixing after storage and before use. Increased stability against shearing forces during industrial use in various applications has been found. As a result, such emulsions have been used extensively in such applications
3.1 Introduction .................................................................................................. 101 3.2 Historical Development ................................................................................ 102 3.3 Overview of Process Types .......................................................................... 102 3.4 Precipitation Polymerization ........................................................................ 104 3.5 Suspension Polymerization ........................................................................... 105 3.6 Internal Suspension Polymerization ............................................................. 106 3.7 Emulsion Polymerization .............................................................................. 107
3.7.1 Past Published Mechanisms ............................................................. 107 3.7.2 Experimental Results of Past Publications ....................................... 108 3.7.3 A New Mechanism: Coagulative Homogeneous Nucleation ............ 111
3.7.3.1 Proposed Mechanism Based on Experimental Results of Past Publications ............................................................ 111
3.7.3.2 Determined Mechanism Based on Heterogeneous Reaction Kinetics ............................................................... 114
3.8 Mini-Emulsion Polymerization .................................................................... 115 3.9 Concluding Remarks .................................................................................... 116 References .............................................................................................................. 116
as protection of freshly printed ink on paper in the web printing process and in the treatment of fabric in textile mills to enhance the soft feel of textiles. Emulsions produced by this method can have extremely small particle size (nanoemulsion) such as 25 nm. These appear transparent or translucent and can be added to clear, water-based products to add the characteristics of silicone polymers without loss of customer product clarity. These nanoemulsions have been extensively used in the production of clear conditioning shampoo.
