It is interesting to note that we observe a correlation between the average MW of the co-polymer, the lactide to glycolide ratio and T g,β and T g,α in PLGA. Here, we first consider the role of the dynamics of chain ends in the limit of the long, high MW PLGA chains: chain ends of any given polymer are only constrained at one end and thus exhibit a greater mobility compared to internal chain segments, which are constrained at both ends of each monomer. At any given temperature, an increase in the number of chain ends is therefore directly related to an increase in free volume. The Fox-Flory equation is a widely used empirical expression that predicts the behaviour of T g as a function of average MW: 41,42