2-Methylene-1-dioxolane, free radical

Methylene- 1,3-dioxolane (15) is polymerized by peroxide initiator to produce a polyester 16 which is regarded as the product of the hypothetical ring-opening polymerization of the non-polymerizable heterocycle of y-butyrolactone (Eq. (14)).13). The opening of the cyclic species bearing a free radical 17 is the key step. 

Also, cross-linked polyesters can be easily made by reaction of CKAs with vinyl cross-linkers with more than one double bond. In one of the studies, porous monolithic supports for tissue engineering were made by electron-beam-initiated free-radical polymerization of 2-methylene-4-phenyl-l,3-dioxolane with trimethylolpropane triacrylate as a cross linker [24]. 

Pan, C.Y. and Lou, X.D. (2000) Living free radical ring-opening polymerization of 2-methylene-4-phenyl-l,3-dioxolane by atom transfer radical polymerization. Macromol. Chem. Phys., 201, 1115. 

The molecular weight of the polymers can be controlled by the concentration of free radical initiator and/or chain transfer agents such as carbontetrabromide. The typical results of poly(perfiuoro-2-methylene-4-methyl-l,3-dioxolane) prepared using different amounts of the initiator and chain transfer agent are shown in Tables 16.3-16.5. 

Perfluoro-2-inethylene-l,3-dioxolane monomers copolymerizes with various commercially available fluorovinyl monomers, too. Perfluoro-3-methylene-2,4-dioxabicyclo [3,3,0] octane (Figure 16.5F) was copolymerized with chlorotrifluo-roethylene (CTFE), perfluoropropyl vinyl ether, perfluoromethyl vinyl ether, and vinylidene fluoride [23] by a free radical initiator such as perfluorodibenzoylperox-ide or tert-butyl peroxypivalate in bulk or in solution, respectively (see Figure 16.9). 

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