The following is a combined QM/MM ab initio molecular dynamics simulation of the chain termination process which we propose to occur through an hydrogen transfer to monomer mechanism. The MM region includes the large iso-propanated phenyl rings which was treated with the AMBER95 force field. The remaining QM region was calculated at the non-local DFT level. The dynamics is thermostated at 300 K. The slow-growth method was used to obtain an estimate for the free energy barrier of the process. A special "mid-plane" reaction coordinate was utilized for the slow growth.