Copolymerization of Tetrahydrofuran with 3,3-Bis chloromethyl Oxetane

The polymerization of 3,3-bis(chloromethyl)oxetane (BCMO) initiated with living polytetrahydrofuran (polyTHF) was studied by Saegusa 117). In this system, due to the high equilibrium concentration of THF, some monomer remains in equilibrium with the polymer after the first stage is completed (i.e. at the polyTHF THF equilibrium). After addition of the second monomer, the remaining THF may participate in copolymerization with added BCMO (cf. Sect. 15.2.2.1., copolymerization above T0), leading to random copolymer. Only after the complete consumption of THF the second monomer may form the required homoblock. Thus, the two homoblocks are separated by a third random BCMO/THF copolymer block  

Solubility data, and IR and DSC analysis, indicated triblock copolymer formation. 

When the second stage leading to statistical copolymer was suppressed by lowering the temperature (and thus decreasing [THF]e), a copolymer whose structure was close to AB (diblock) was obtained. 

Yamashita et al. claimed the preparation of the following block copolymers, with living polyDXL as the first block 118  

Copolymerizations were carried out at ambient temperatures in CH2C12 solvent using (C2Hs)3OffiBF initiator. 

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