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 bioadhesi ve vehicles for drug delivery. In order to have a greater understandin g of the factors affecting drug release from these gels, it is necessa ry to develop methods of studying their physical properties. In this i nvestigation, Carbopol 934 gels have been studied using dielectric spe ctroscopy and oscillatory rheometry. The effect of a number of variabl es on the dielectric and rheological behaviour have been studied; thes e 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 i nterpreted in terms of the structure of the gel network and suggest th at the use of these two techniques in conjunction provides an effectiv e means of assessing the properties of gel systems. In particular, the presence of both propylene glycol and chlorhexidine gluconate were sh own to have a marked effect on the gel structure, although the results indicated that the mechanisms involved were different.