The second investigated reaction path was insertion of TMA after the ester oxygen. This product was found for both polymers, however the difference in location of the C=O group between PLA and PMMA strongly influences the final geometry of the product, as shown in TMA is inserted into PLA, the backbone of the polymer is severed as the DMA chelates to the two oxygen atoms on the carboxyl terminal, while a methyl group is transferred to the carbon-head of the fragment chain. The chain is however able to reattach due to the DMA group crosslinking the two fragments. The insertion reaction is more exothermic than methyl transfer with a reaction energy -2.56 eV relative to the adduct, while breaking the crosslink between the two fragments is endothermic with an energy cost of 0.62 eV. The most notable change in the IR spectrum for TMA insertion into PLA is a redshift of 89.66 cm -1 for the C=O stretch mode of the crosslinked oxygen and the addition of two new peaks at 1725.42 cm -1 and 1542.98 cm -1 corresponding to asymmetrical and symmetrical stretch modes of the chelating carboxyl terminal.