AN INVESTIGATION INTO THE STRUCTURE AND PROPERTIES OF CARBOPOL-934 GELS USING DIELECTRIC-SPECTROSCOPY AND OSCILLATORY RHEOMETRY

Carbopols are polyacrylic acid polymers which may be used as bioadhesive vehicles for drug delivery. In order to have a greater understanding of the factors affecting drug release from these gels, it is necessary to develop methods of studying their physical properties. In this investigation, Carbopol 934 gels have been studied using dielectric spectroscopy and oscillatory rheometry. The effect of a number of variables on the dielectric and rheological behaviour have been studied; these include the presence of a gelling agent (triethanolamine), changing the concentration of polymer, the addition of propylene glycol and the addition of a model drug (chlorhexidine gluconate). The results are interpreted in terms of the structure of the gel network and suggest that the use of these two techniques in conjunction provides an effective means of assessing the properties of gel systems. In particular, the presence of both propylene glycol and chlorhexidine gluconate were shown to have a marked effect on the gel structure, although the results indicated that the mechanisms involved were different.