"Biphasic high-pressure CO2 systems for the synthesis and modification of polymeric materials"

Abstract:

Nowadays, the general vector of polymer science development is pointed at respecting the environment, at refusing to use potentially allergenic substances in the biomedical field, at meeting the requirements of extra purity in catalysis applications, and at imparting new functional properties to composites. In this regard, studies in biocompatible solvents that do not require subsequent neutralization, such as water saturated with CO₂ under high pressure (solution of carbonic acid), as well as in pure supercritical (SC) CO₂, that can impart new properties with advantages to substances modified in such media, look promising.

The technology of supercritical fluids, and more generally high-pressure solvents, has been successfully used in such areas of chemical engineering as organic synthesis, extraction, etc. Among the advantages of supercritical fluids and solutions under high pressure are their high penetrating and dissolving ability, controlled by applied pressure and temperature, environmental safety, as well as an atypical combination of antimicrobial activity (under pressure and during decompression) and biocompatibility (after decompression and at normal pressure). However, the technology of high-pressure solutions (for example, carbonic acid solutions formed under high pressure CO₂ saturating the aqueous phase) remains very little studied in relation to the dissolution and modification of polymeric materials, the creation of composites based on them, in particular, for biomedical applications or applications that require increased purity.

This presentation will focus on what polymers’ modifications can be done in biphasic media, containing CO₂ under high pressure, and what benefits it possess for materials engineering. We will discuss the possibility to dissolve polycations in such media and to create composite hydrogels with metal nanoparticles, thin films covering different materials, highly porous sponges, etc. on the basis of such solutions. Further, cleaning of different materials such as bones, bacterial cellulose or chitosan sponges from low and high molecular weight substances will be addressed. Time will also be given to overview the micronization of the drugs that can proceed in the high-pressure media and the supercritical solvent impregnation of drugs in the polymer matrix for fabrication a drug delivery system.