A novel polymer dispersant with a tri-block structure was designed. The tri-block polymer was composed of polyglycerin (PGL) with two dimethylpolysiloxane chains (DMPS) at both ends of the molecular structure. The high dispersibility of the dispersant was confirmed in both a model silica system and a sunscreen formulation. The apparent silica particle size was employed as an index for the dispensability for the dispersants. The novel dispersant showed 5 times more effective than conventional one. The flow properties of a sunscreen formulation containing titanium dioxide with the novel dispersant was Newtonian, indicating that the dispersibility of the dispersant was excellent. On the other hand, the formulation with conventional dispersant showed shear-thinning flow due to aggregation of the powder. These results mean that such a tri-block copolymer would make it possible to develop consumer demanded sunscreens.
The viscosities of LiCl, KCl, and CsCl have been measured in water and aqueous solutions containing 0.398 mol/dm3 of 18-crown-6 (CR) at 25 °C. The B-coefficients of the alkali metal chlorides in water have been obtained using the theoretical values of the A-coefficients. The viscosity coefficients of 18-crown-6 itself have been determined in water and methanol. In systems containing crown ether, the viscosity increment due to the complex formed in solutions, Δη[CR–M+]Cl−, has been evaluated by subtracting from the observed viscosity the increment attributed to non-coordinated crown ether and alkali metal chlorides in solutions. The two complex ions, [CR-K+] and [CR-Cs+], have nearly the same values of the B-coefficients, and these values are, in turn, approximately equal to that of 18-crown-6 in water. Measurements done on KCl in methanol containing 18-crown-6 have led to the finding that in methanol, 18-cown-6 and the [CR-K+] ion take effectively the same B-value.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.