Pigment nanoparticles with a size range of 10~100 nm were produced from large agglomerates via a stirred media mill operating in the wet-batch mode and using polymeric media. The effects of several operating variables...Pigment nanoparticles with a size range of 10~100 nm were produced from large agglomerates via a stirred media mill operating in the wet-batch mode and using polymeric media. The effects of several operating variables such as the surfactant concentration, polystyrene media loading, and media size on the pigment size distribution of the product were studied. The process dynamics was also investigated. Dynamic light scattering and electron microscopy were used as the characterization techniques. The polymeric grinding media are found to be effective for the production of pigment nanoparticles. The experimental results suggest the existence of an optimum media size and surfactant concentration. A population balance model of the process reveals a transition from first-order breakage kinetics for rela-tively coarse particles to non-first-order kinetics, with a delay period, for the smaller particles. The model implies that large agglomerates split in a first-order fashion whereas the breakage of individual nanoparticles may depend on induced fatigue of the particles.展开更多
Superdisintegrants are cross-linked polymers that can be used as dispersants for fast release of drug nanoparticles from nanocomposite microparticles during in vitro and in vivo dissolution. Currently avail- able supe...Superdisintegrants are cross-linked polymers that can be used as dispersants for fast release of drug nanoparticles from nanocomposite microparticles during in vitro and in vivo dissolution. Currently avail- able superdisintegrant particles have average sizes of approximately 5-130 μm, which are too big for drug nanocomposite applications. Hence, production of stable superdisintegrant suspensions with less than 5 μm particles is desirable. Here, we explore the preparation of colloidal suspensions of anionic and nonionic superdisintegrants using a wet stirred media mill and assess their physical stability. Sodium starch glycolate （SSG） and crospovidone （CP） were selected as representative anionic and nonionic superdisintegrants, and hydroxypropyl cellulose （HPC） and sodium dodecyl sulfate （SDS） were used as a steric stabilizer and a wetting agent/stabilizer, respectively. Particle sizing, scanning electron microscopy, and zeta potential measurements were used to characterize the suspensions. Colloidal superdisintegrant suspensions were prepared reproducibly. The extensive particle breakage was attributed to the swelling-induced softening in water. SSG suspensions were stable even in the absence of stabilizers, whereas CP suspensions required HPC-SDS for minimizing particle aggregation. These findings were explained by the higher absolute （negative） zeta potential of the suspensions of the anionic superdisintegrant （SSG） as compared with those of the nonionic superdisintegrant （CP）.展开更多
文摘Pigment nanoparticles with a size range of 10~100 nm were produced from large agglomerates via a stirred media mill operating in the wet-batch mode and using polymeric media. The effects of several operating variables such as the surfactant concentration, polystyrene media loading, and media size on the pigment size distribution of the product were studied. The process dynamics was also investigated. Dynamic light scattering and electron microscopy were used as the characterization techniques. The polymeric grinding media are found to be effective for the production of pigment nanoparticles. The experimental results suggest the existence of an optimum media size and surfactant concentration. A population balance model of the process reveals a transition from first-order breakage kinetics for rela-tively coarse particles to non-first-order kinetics, with a delay period, for the smaller particles. The model implies that large agglomerates split in a first-order fashion whereas the breakage of individual nanoparticles may depend on induced fatigue of the particles.
基金financial support from the U.S.National Science Foundation Engineering Research Center for Structured Organic Particulate Systems(NSF ERC for SOPS) through the Grant EEC-0540855
文摘Superdisintegrants are cross-linked polymers that can be used as dispersants for fast release of drug nanoparticles from nanocomposite microparticles during in vitro and in vivo dissolution. Currently avail- able superdisintegrant particles have average sizes of approximately 5-130 μm, which are too big for drug nanocomposite applications. Hence, production of stable superdisintegrant suspensions with less than 5 μm particles is desirable. Here, we explore the preparation of colloidal suspensions of anionic and nonionic superdisintegrants using a wet stirred media mill and assess their physical stability. Sodium starch glycolate （SSG） and crospovidone （CP） were selected as representative anionic and nonionic superdisintegrants, and hydroxypropyl cellulose （HPC） and sodium dodecyl sulfate （SDS） were used as a steric stabilizer and a wetting agent/stabilizer, respectively. Particle sizing, scanning electron microscopy, and zeta potential measurements were used to characterize the suspensions. Colloidal superdisintegrant suspensions were prepared reproducibly. The extensive particle breakage was attributed to the swelling-induced softening in water. SSG suspensions were stable even in the absence of stabilizers, whereas CP suspensions required HPC-SDS for minimizing particle aggregation. These findings were explained by the higher absolute （negative） zeta potential of the suspensions of the anionic superdisintegrant （SSG） as compared with those of the nonionic superdisintegrant （CP）.
