Biodegradable polymers are used in medical devices such as fixation plates, sutures, or micro particles for the controlled release of drugs. Typical polymers are poly lactic acid (PLA), poly glycolic acid (PGA), and poly caprolactone (PCL). During degradation, the ester bonds within polymer chains are cleaved due to the hydrolysis reaction in the presence of water. It has been suggested that both chain end scission and random chain scission occur and mathematical models have been able to fit experimental data with assumptions of random scission, end scission, or a combination of both. In random scission, every bond in a polymer chain is assumed to be equally susceptible to hydrolysis.
Gel permeation chromatography (GPC) is often used to determine molecular weight. In GPC the time taken for polymer chains to pass through a column of porous beads is affected by their molecular weight. The fraction of the polymer within chains of a given molecular weight range can be calculated to find the distribution of molecular weights.
Last date updated on July, 2014