polymerization should be equal to the number of catalysts in solution, and that the average degree of polymerization of the sample at the end of polymerization should be equal to the ratio of monomers to catalysts in solution. Termination A characteristic of CTP is living chain-growth character, meaning that the catalyst will have a reactive chain end for the entirety of the polymerization. Therefore, to terminate the polymerization, a quenching agent must be added, such as a strong acid to protonate the polymer, or a nucleophile to add an end cap the polymer. If the π-complex is too weakly bound, termination of polymer chains can occur before a quenching agent is added, causing lower molecular weight polymers to form. Current research into CTP focuses on finding catalysts that form strong catalyst-polymer π-complexes such that the polymerization remains living. Analysis Success of CTP is often evaluated using gel permeation chromatography, matrix-assisted laser desorption/ionization, nuclear magnetic resonance spectroscopy. GPC characterization enables determination of average molecular weight. MALDI and NMR allow for identification of end groups of the polymer chain. Polymer Reactivity versus π-complex The chain growth nature of CTP can also be described without invoking a catalyst-polymer π-complex. If we assume that no π-complex forms and instead every time a monomer was added to a polymer, the polymer becomes more reactive, we would also see chain growth since the largest polymers in the reaction would be the most reactive and would react with monomers preferentially. The presence of this mechanism and one mediated by a π-complex can be elucidated by studying the end groups of the polymers using mass spectrometry. Polymers That Can Be Synthesized via CTP A non-exhaustive list of the polymers that can be synthesized using CTP: Polythiophene Polyphenylene Polyselenophene Polytellurophene Polythiazole Polybenzothiadiazole Polypyrrole Polyfluorene References Polymerization reactions