Application of 2D correlation spectroscopy with MCR in the preparation of glycerol polyesters

The condensation of glycerol and adipic acid was studied by 2D correlation spectroscopy in combination with MCR to identify spectral changes associated with this polymerization reaction and to describe the development of structure in the polymer. This biobased polymer is being evaluated for use as a controlled release matrix where the extent of reaction is a key performance parameter. A spectroscopic technique was sought to estimate the extent of reaction and guide product development. FT-IR spectra were collected as the reaction was performed on a temperature programmable ATR assembly fitted to a Bruker Tensor 27 spectrophotometer. The resulting time series was analyzed by 2D correlation spectroscopy. Correlation maps were used to identify bands related to the formation of the polymer and multivariate curve resolution (MCR) was applied to develop a model in terms of pure components. This combined technique offers a rapid method for sample analysis and facilitates the preparation of materials to a specified extent of reaction.