The effects of plasticizers and titanium dioxide on the properties of poly(vinyl alcohol) coatings.

Poly(vinyl alcohol) has not previously been examined in much detail as a controlled release polymer for use in pharmaceutical formulations. However, this food grade polymer has barrier and tensile properties which make it attractive for such applications. The effects of several diluents and fillers on Poly(vinyl alcohol) (PVAL) coatings have been determined using both mechanical property and water vapor permeability measurements. It has been found that the alcohol ethoxylate Neodol 23-6.5 (CH3(CH2)11-O-(CH2-CH2-O)6-H) acts as a plasticizer for PVAL only up to 15-20 wt% in contrast to 600 molecular weight Polyethylene Glycol (PEG 600), which continuously plasticizes PVAL. The effects of Neodol on PVAL mechanical properties and water vapor permeability at higher concentrations can be explained in terms of Neodol phase separation and has been confirmed with DSC. The inert filler and whitener titanium dioxide (TiO2) monotonically degrades film mechanical properties and increases water vapor permeability of the coating. Attempts to correlate coating dust generated during particle attrition tests with mechanical property measurements were unsuccessful. A correlation between accelerated granule stability and water vapor permeability of the PVAL coating was established.

Solubilization of subtilisin in CO2 using fluoroether-functional amphiphiles.

Carbon dioxide is a naturally abundant, environmentally benign solvent whose use, like water, in a process is not regulated by either EPA or FDA. Unfortunately, polar compounds such as amino acids and proteins are essentially insoluble in carbon dioxide. Further, alkyl-functional surfactants, which have been shown to allow extraction of proteins into conventional organic solvents, exhibit very poor or negligible solubility in CO2 at pressures below 50 MPa. Consequently, highly CO2-soluble fluoroether-functional surfactants have been generated and used to solubilize subtilisin Carlsberg from aqueous buffer and cell culture medium into CO2, with recovery accomplished by depressurization. Both the amount of protein solubilized in the emulsion and the extent of activity retention by the protein following recovery are functions of the initial protein concentration in the buffer. This, plus the observation that the presence of protein affects the stability of the emulsion, suggests that some of the protein is sacrificed to act as a stabilizer in these systems. In addition to solubilization via an inverse emulsion, it has also been shown that one can strip protein-surfactant aggregates from a middle phase emulsion using pure CO2, suggesting an ion-pairing type mechanism.