The THF-CF3SO3H System

In the THF-CF3SO3H system the initiating acid is not completely consumed at the monomer-polymer equilibrium. As illustrated by the data shown in Table 6.1 the molecular weights of the products formed exceed many times the values calculated by  

Reaction system (molar ratio) Time, h Conversion, % M. calcd. M. measured 

To describe such a system the equilibrium acid concentration has to be included in Eq. (6.3) thus  

However it was not proven, that the observed results are not of kinetic origin, i.e. due to slow propagation. In such a scheme, growth would proceed on active species formed only by a small fraction of acid, and at the moment monomer-polymer equilibrium was reached some amount of unconsumed add would still remain. 

When fluosulfonic acid (FS03H) was used as the initiator of THF polymerization, the higher molecular weight polymer with DP ([THFJo — [rHF]e/[FS03H]o was formed initially. In the further course of the reaction, the molecular weight decreased and approached calculated values. HF is formed during the polymerization and as determined by 19F-NMR its ultimate concentration equals that of FSOaH 13). The results of a typical polymerization are summarized in Table 6.2. 

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