E, are commonly about 1.three V vs. Ag/Ag [54], though alkyl-substituted EDOTs
E, are typically about 1.three V vs. Ag/Ag [54], when alkyl-substituted EDOTs, like EDOT-C12, and three,4-dialkoxy-substituted thiophenes, for example three,4-BHOT, are ordinarily about 0.9 V [55] and 1.1 V vs. Ag/Ag [56], respectively. Mainly because the oxidation potential of 3-hexylthiophene is greater than the GSK2646264 supplier ether-substituted monomers, it may be necessary to retain a larger answer prospective through polymerization to obtain high Xw for P3HT, whereas polymerization of monomers with decrease oxidation potential, for instance EDOT-C12 and three,4-BHOT, may nonetheless be successful even when the oxidation prospective on the option is lowered. Subsequent, we think about the oxidation prospective of your reaction option, and its potential impact around the mechanism of polymerization (summarized in Table 4). When reverse order of addition is employed, the oxidation possible from the remedy is higher because the solvent keeps the concentration of dissolved FeCl2 low, as well as the relative oxidant/monomer ratio is high. These circumstances should really raise the step-growth PHA-543613 site character in the polymerization mechanism since all species in solution (monomers, oligomers, and polymers) could be oxidized and take part in polymerization reactions. Within a step-growth mechanism, high yields and low molecular weights are typical, which coincides with what is observed for PEDOT-C12 and PBHOT. On the other hand, when the regular addition approach is applied, the oxidation prospective of the resolution is low for the reason that the binary solvent mixture makes it possible for for a a lot greater concentration of dissolved FeCl2 , and the relative oxidant/monomer ratio is kept low. These circumstances should really enhance the chain-growth character in the polymerization mechanism, where the oxidation of longer polymer chains is favored over monomers and oligomers, which possess a higher oxidation potential. Therefore, polymer growth occurs by the consecutive addition of monomers to active (oxidized) polymer chains, resulting in low yields but high molecular weights, which can be observed for PEDOT-C12 and PBHOT. The kinetics with the FeCl3 -initiated polymerization of thiophene in chloroform and acetonitrile happen to be studied by Olinga and Fran is [41], who reported the polymerization mechanism had some degree of solvent-dependence. Even though the trends described in Table four describe what is observed for the ether-substituted polymers, they usually do not reflect what is observed for P3HT. Xw and yields decrease for P3HT when normal addition is used rather than reverse addition, likely on account of effect on the distinct polymerization solvents [36]. The stark contrast in polymerization behavior among the ether-substituted polymers and P3HT suggests electronic variables (the oxidation possible with the monomer and solution) have the biggest influence around the Xw obtained. Consequently, these factors really should be viewed as initial when looking for to optimize the polymerization situations to different monomers. In the comparable behavior observed for both PEDOT-C12 and PB-Materials 2021, 14,12 ofHOT, it could be concluded that steric hindrance slows the polymerization reaction but does not considerably change the polymerization behavior. Reverse addition does not result in a higher degree of polymerization for the electron-rich ether-substituted thiophenes [31,32]. Consequently, standard addition must be regarded as the approach of choice for chemical oxidative polymerization of ether-substituted polymers if a higher degree of polymerization is desired.Table four. Summary of variations among orders of addition and also the tr.