Čes. slov. farm. 2009, 58(5):212-215

Adhesivity of branched plasticized oligoesters

E. Šnejdrová^*, M. Dittrich

Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Technology

This paper compares the rheological and adhesive properties of branched oligoester carriers plasticized with the use of various types and concentrations of plasticizers. The oligoesters tested and reported here are star-like branched terpolymers of dipentaeythritol, D,L-lactic acid and glycolic acids, where dipentaerythritol (D) was employed as the branching agent in three concentrations (3%, 5% or 8%) in synthesis by step-by-step polycondenzation. Carriers labelled as 3D, 5D and 8D were plasticized with either triethyl citrate (TEC), or methyl salicylate (MS), or ethyl salicylate (ES) in various concentrations. Dynamic viscosity of plasticized oligoesters was measured at 37 °C. Plasticized systems behaved as Newtonian fluids, their viscosity depended mainly on plasticization, and then on the molecular weight and branching ratio of the carriers. Detachment force as the measure of the adhesiveness of the plasticized carriers was determined. Adhesive forces of the tested carriers ranged most frequently between 25 N and 35 N with the corresponding values of dynamic viscosity from 3 Pa.s to 40 Pa.s. The optimal range of dynamic viscosity of the plasticized carriers providing sufficient bioadhesion was found out.

Keywords: branched oligoesters; plasticizer concentration; viscosity; bioadhesion

Grants and funding:

This study was supported by the grant MSM 0021620822.

Received: October 29, 2009; Accepted: November 4, 2009; Published: May 1, 2009  Show citation