Study of polysaccharidic basic for emulsions:interactions between polymer-surfactant and rheological properties

摘要

Properties and behaviour of polysaccharidic solutions, meant to be employed as the continuous phase of cosmetic emulsions, have been studied by means of rheometric and tensiometric techniques. The first step has been the measurement of tensiometric properties of diluted solutions of a nonio-nic siliconic surfactant (dimethycone copolyol) and of a cationic surfactant (cethyl trimethylammonium bromide, C_(14)TAB) and of their mixtures: filling of data has been provided, according to mathematical models currently used in literature. The second step has been the study of the rheologi-cai properties (oscillatory and steady state measurements) of scleroglucan (a polysaccharide) solutions, at different concentration levels. The third step has been the analysis of rheometrical data obtained from solutions of the polysaccharide, whose content has been fixed at 0.4% w/w, mixed with the surfactants (taken singularly): their interactions have been explained on the assumption of the formation of polymer-surfactant complexes. Moreover, the interactions between both surfactants and the polysaccharide at two fixed surfactant concentrations (5 and 10% w/w) have been considered: it has been found out that both surfactants should be used in order to obtain a polysaccharidic matrix with good mechanical properties. According to these results, several emulsions have been prepared and characterized, the dispersed phase being a siliconic oil: while the total surfactant content has been kept constant (5% w/w), variable quantities of dispersed phase and polysaccharide have been considered.