New hydroxyproline based methacrylic polybetaines: Synthesis, pH sensitivity and catalytic activity

The synthesis of two new types of methacrylic polybetaines bearing trans-4-hydroxy-l-proline connected via its hydroxyl group is described, one with an aliphatic spacer of 6 carbon atoms and the other without any spacer. The pH sensitivity in aqueous media and the catalytic activity of the products in asymmetric aldol additions have been studied. The two polyzwitterions show an isoelectric point (IEP) close to 3. Swelling of networks prepared with the two monomers exhibit reversible pH sensitivity; the largest the pH distance from the IEP, the higher the net charge (positive or negative) and the higher the swelling. At basic pH and an ionic strength of 0.15, maximum swelling degrees of around 11 and 24 (g water/g polymer) have been found for the systems with and without spacer respectively. The polymers have been shown to be efficient catalysts for aldol reactions under homogeneous conditions in DMF but not in water.     

Latex as a sunscreen carrier in a silicone vehicle

This work comprises a study of the adsorption-desorption of three chemical sunscreens on the polymer surface of the latex Aquacoat, which has a high specific surface. The aim was to delay the release of these filters from the silicone excipient containing them and therefore increasing the substantivity, i.e. prolonging the sunscreening effect.     

Development, formulation, and effectiveness testing of a silicone-based barrier-type hand cream

We report the development, design, and results of effectiveness and acceptability testing of a hydrating, nutritive, barrier-type hand cream designed for severely damaged skin (including skin damaged by dermatological problems). We tested different silicone derivatives and a water-in-oil (W/O) silicone emulsifier to produce organoleptic qualities that would increase consumer acceptance of this type of W/O emulsion. Pharmacotechnical and effectiveness tests were done to check the stability and preservation of the formulas, their usefulness in improving dry skin, and acceptance by users. The results of pharmacotechnical testing were optimal. Although no active principle aimed specifically at dermatological problems was present in the final formulas, users reported notable subjective improvements in cracking and scaling.