Transesterification vitrimers often require high catalyst loadings to achieve 3D networks reprocessable at moderately high temperature. The addition of an activating group close to the ester bonds allows to synthesize catalyst-free transesterification vitrimers. Here, we unveil the effect of the α-difluoromethylene group as a novel activating group for such materials. Fluorine features exceptional properties, in particular a strong electronegativity enabling CF₂ groups to activate the epoxy-acid polymerization, and more interestingly also the transesterification reaction on adjacent esters. Consequently, this fluorinated group affords the easy synthesis of a highly crosslinked reprocessable material that do not require any metallic or organic catalyst. This vitrimer is endowed with advantageous reprocessing abilities and underwent 10 consecutive cycles without loss of mechanical properties. In brief, the vitrimer combines durability, recyclability and is catalyst-free. This discovery is one step further towards recyclable greener polymers.

The copolycondensation of siloxane and silane bearing hydrido and methoxy groups, respectively, was carried out in a surfactant‐free aqueous emulsion, at room temperature and using B(C₆F₅)₃ as a water‐tolerant Lewis acid. Several characterization techniques, including triple detection SEC, ²⁹Si NMR and MALDI‐TOF, confirmed the generation of linear polymers (no macrocycles), of average molar masses ranging between 30 and 80 000 g · mol⁻¹, and bearing silanol end‐groups. Colloidal evolution with time showed that a stable surfactant‐free emulsion was generated before some coalescence occurs by decreasing the content of silanol groups suspected to stabilize the emulsion. The kinetics of reaction was followed by SEC, and revealed the generation of small cycles, along with linear oligomers, before converting them to poly(dimethylsiloxane) chains. A tentative mechanism, where ring‐opening polymerization of the most stranded cyclosiloxane and polycondensation of polymer chains are considered, is proposed. magnified image