Cyclopolymerization of tert-butyl α-(hydroxymethyl) acrylate (TBHMA) ether dimer via atom transfer radical polymerization (ATRP)

Atom transfer radical polymerization (ATRP) was used in the cyclopolymerizaton of a symmetrical dimethacrylate, the ether dimer of tert-butyl alpha-(hydroxymethyl)acrylate (TBHMA). The cyclopolymerization was succesfully carried out with high cyclization efficiency in xylene using CuBr/PMDETA at 70 degrees C. Cyclopolymers with six membered tetrahydropyran repeat units were obtained in high conversions with controlled molecular weights and low polydispersities. It was found that at higher temperatures (100 degrees C), the polymerization became less controlled and polydispersities increased slightly whereas at lower temperatures (50 degrees C) the intermolecular reactions lead to pendent vinyl groups and cross-linking. The livingness of the propagating cyclopolymers was shown through successful block copolymerization with tert-butyl acrylate where the former was used as macroinitiator. The physical properties of the cyclopolymers were investigated and it was found that ring microstructures and polymer polydispersities affected the glass transition temperatures of the polymers obtained.