Polymers supercritical anti-solvent

In Tables 9.9-3 to 9.9-5 a summary of the recrystallization process of pharmaceuticals and bio-polymers, and co-precipitation by supercritical anti-solvent is presented. In Figures 9.9-1 and 9.9-2 examples of very long needle crystal and nano-particles are reported. 

Wang, Y., et al. (2004), Polymer coating/encapsulation of nanoparticles using a supercritical anti-solvent process, /. Supercrit. Fluids, 28, 85-99. 

The protein-polymer microcapsules can be obtained by supercritical anti-solvent techniques [8]. Homogeneous protein-polymer mixtures were contacted with supercritical carbon dioxide in order to produce microspheres with diameter ranging from 1 to 5 pm and containing around 80% of protein. Production of PLA microparticles containing insulin, lysozyme, and chemotrypsin is claimed. SAS crystallization of a pharmaceutical (naproxen) and a biodegradable poly(L-lactic acid) was reported [8]. The results from SAS studies showed very small spherical particles... 

Both the nucleation of supercritical anti-solvent bubbles in a polymer+organic solvent-rich phase in the supercritical anti-solvent process (SAS) (or, equivalently, precipitation with a compressed antisolvent PCA) (e.g., [76]) and the nucleation of bubbles of a dissolved supercritical fluid from a saturated and nozzle-expanded solution containing a solute to be precipitated, in the formation of particles from gas-saturated solutions (PGSS) [77] are bubble nucleation problems, to which the above ideas apply. In the latter case, the nucleation of bubbles occurs simultaneously with that of solid particles within the bulk supersaturated solution. 

Supercritical fluids can be used to extract substances from natural products, as solvents or as anti-solvents to micronize drugs and biodegradable polymers, encapsulate drugs in polymeric matrices, resolve racemic mixtures of pharmacologically active compounds, fractionate mixtures of polymer and proteins, and sterilize bacterial organisms. 

In the latest literature, the production by supercritical techniques of pharmaceuticals-loaded bio-polymer micro-particles is widely considered [34], All of these applications take advantage of the solvent or anti-solvent power of CO2. Various techniques have been proposed so far, such as the rapid expansion from supercritical solution (RESS) [35], the gas... 

One of the requirements for the development of new polymer processes based on SCCO2 is knowledge about the phase behavior of the mixture involved, which enables one to tune the process variables properly to achieve maximum process efficiency. Important parameters in the phase behavior of the system are the solvent quality, the molecular weight, chain branching, and chemical architecture of the polymer, as well as the effect of end groups, and addition of a co-solvent or an anti-solvent. The literature available on the phase behavior of polymers in supercritical fluids has been reviewed extensively by Kirby and McHugh [38]. 

Kluge, J., Fusaro, F., Muhrer, G., Thakur, R., Mazzotti, M. (2009). Rational design of drag-polymer co-formulatianti-solvent precipitation. The Journal of Supercritical Fluids. 48. 176-182. 

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