POLYMER STRUCTURE FEATURES CONTRIBUTING TO MUCOADHESION .2.

The influences of polymer charge group and charge related properties on mucoadhesion were studied by synthesizing a series of 0.2% cross-linked copolymers (acrylic acid-methyl methacrylate). The process of mucoadhesion may be divided into two stages, the first of which is establishment of intimate contact between the mucoadhesive polymer and mucin. In the second stage, electrostatic, hydrophobic and hydrogen bonds are formed and the interpenetration process increases the contact area between the mucoadhesive and mucin and thus enhances bond formation. Mucoadhesive tensile strength was found to depend on contact time and temperature of the environment, and was found to be proportional to the mean diffusional path of the polymer into the mucin layer. It is likely that the expanded nature of both the mucin and the polymer network influences the process of interpenetration/interdiffusion. The average infrastructural mesh size of the copolymer was found to be proportional to the amount of the acrylic acid in the copolymer network. A relationship between tensile stress and average mesh size is proposed. It appears that mucoadhesive with the desired mucoadhesive strength can be designed by controlling the percentage of charged groups and the corresponding openness of the network. © 1990.