Trifluoromethanesulfonic anhydride initiator

Symmetric triblock copolymers of the ABA type, where B was PTHF and A poly(2-methyl-2-oxazoline), PMeOx, were prepared by cationic polymerization with trifluoromethanesulfonic anhydride as a difunctional initiator [58]. Subsequent hydrolysis of the PMeOx blocks with HC1 in a methanol/ water mixture resulted in the formation of the corresponding polyethylen-imine blocks (Scheme 20). Samples with relatively low molecular weight distributions were obtained. 

Acetals are one of a few groups of monomers for which the best general polymerization conditions can be given. Thus, if the aim is the preparation of high-molecular-weight polyacetals we would advise to use <0.1 mol % trifluoromethanesulfonic anhydride well below 0 °C in bulk. If the polymerization proceeds violently under these conditions and the time for mixing is insufficient to obtain uniform solution, both temperature and initiator concentration should be decreased. 

Esters of very strong protonic acids (trifluoromethanesulfonic, fluoro-sulfonic, perchloric), however, are sufficiently strong alkylating agents to initiate the polymerization of even weakly nucleophilic monomers (cyclic acetals, ethers) [2-6], Also their anhydrides (e.g., triflic anhydride) are efficient initiators. This last compound is especially interesting, because in the polymerization of cyclic ethers it leads to macromolecules with two identical growing chain ends (difunctional initiator) [30] ... 

Obtain polymer by isobisisobutyronitrile as an initiator to polymerize it in benzene at 65°C for 48 h. After refining, evaporate the solvent slowly from the mixed solution that dissolved the alkaline salt along with the lithium trifluoromethanesulfonic acid in the anhydride methanol solvent. Solid-state auxiliary battery using a gel electrolyte... 

Most commonly initiation proceeds as direct addition of initiator to monomer molecule (route 1). Cationic polymerization of cyclic ethers may be initiated by both Bronsted and Lewis acids. Most commonly used initiators include strong protic acids such as trifluoromethanesulfonic (triflic) acid (also its anhydride or esters), fiuorosulfonic acid, perchloric acid, or heteropolyacids, oxonium salts such as triethyloxonium (e.g., EtsC A ), carbenium (e.g., Ph3C A ), or carboxonium (e.g., CeHsCO A ) salts where A should be stable, weakly nucleophilic counterion (e.g., BF4, PFg, and SbFg) or Lewis acids (most commonly used is BF3 -Et20). Several other initiation systems have been used (e.g., rare earth triflates) but the advantages over typically used simple and easily available initiators have not always been shown. 

Block polymers using blocks other than PROZO chain were prepared. As a typical example, polytetrahydrofuran (PTHF) was introduced to AB-type and BAB-type block copolymer as shown in Scheme 18. For the synthesis of the diblock copolymer, ethyl trifluoromethanesulfonate (EtOTf) was used as initiator, while for the triblock copolymer, anhydride of TfOH was employed, where a living CROP of THF end, an oxonium species, is involved. PTHF is a hydrophobic chain both copolymers showed very good surfactant properties, when MeOZO or EtOZO was used, as observed by the surface tension value reaching to y = 30.1-28.2. 

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