###### Abstract  
Electrophotographic printing and copying processes primarily use toner, which is a mixture of colorant, polymer, and additives. Toner can be made using traditional mechanical milling techniques or more contemporary chemical polymerization techniques. Suspension polymerization provides spherical particles with less stabilizer adsorption, homogeneous monomers, higher purity, and easier control of the reaction temperature. In contrast to these advantages, however, the particle size resulting from suspension polymerization is too large for toner. To overcome this disadvantage, devices such as high-speed stirters and homogenizers can be used to reduce the size of the droplets. This research investigated the use of carbon nanotubes (CNTs) instead of carbon black as the pigment in toner development. We succeeded in achieving a good dispersion of four different types of CNT, specifically modified with NH\({}_{2}\) and Boron or unmodified with long or short chains in water rather than chloroform, using sodium n-dodecyl sulfate as a stabilizer. We then performed polymerization of the monomers styrene and butyl acrylate in the presence of the different CNT types and found that the best monomer conversion and largest particles (in the micron range) occurred with CNTs modified with boron. The insertion of a charge control agent into the polymerized particles was achieved. Monomer conversion of over 90% was realized with all concentrations of MEP-51, whereas conversion was under 70% with all concentrations of MEC-88. Furthermore, analysis with dynamic light scattering and scanning electron microscopy (SEM) indicated that all polymerized particles were in the micron size range, suggesting that our newly developed toner particles were less harmful and environmentally friendly products than those typically and commercially available. The SEM micrographs clearly showed good dispersion and attachment of the CNTs on the polymerized particles (no CNT aggregation was found), which has never been published before. suspension polymerization; toner; carbon nanotubes; charge control agent; conversion +
Footnote †: journal: materials  
0000-0001-4880-3888-2222-3/00/0000-0000-0000-0000-0000-0000-00000-00000-00000-0000-00000-00000-00000-00000-00000-000000-00000-00000-000000-000  
smaller and more uniform than those in conventional toner [3]. Compared with the traditional approach, a polymerized toner obtains a sharper print and is more environmentally friendly because less toner is used. Suspension [4], emulsion [5; 6], dispersion [7], interface/free radical, and aggregation polymerization are the patented methods for toner preparation. Among these techniques, the suspension method has the advantage of preparing toner particles with a perfectly spherical shape and which absorb less stabilizer than in the other approaches [4]. However, suspension polymerization typically produces particles greater than 5 \(\upmu\)m, which is significantly larger than ideal. To overcome this disadvantage, devices such as magnetic or mechanical high-speed stirrers and homogenizers are employed to reduce the size of the droplets. However, agitation speed, the nature and quantity of the suspension stabilizer, and the volume ratio of the dispersed (organic) and continuous (aqueous) phases can all affect the size of the monomer droplets. This phase of our work mainly concerns the development of toner technology using polymerization, and so we are particularly focused on suspension polymerization. However, the suspension technique is not new, having been invented more than 80 years ago, with [PERSON] and [PERSON] accomplishing the first suspension polymerization--of acrylic monomers that formed beads--in 1931 [8]. [PERSON] et al. [9] state that suspension polymerization is a reaction via free radicals in a heterogeneous medium. Furthermore, suspension polymerization occurs in a liquid (often water) phase, where neither the monomer nor the polymer is soluble.