Synthesis and Characterization of Poly(vinylidene fluoride)- g -poly(oxazoline) Graft Copolymers

Novel graft copolymers based on poly(vinylidene fluoride) (PVDF) bearing poly(2-alkyl-2-oxazoline) (POx) side chains, PVDF- g -POx, were synthesized via a two-step strategy. First, POx macromonomers end-functionalized with 2-(trifluoromethyl)acrylic acid (MAF-POx) were prepared through cationic ring-opening polymerization of 2-alkyl-2-oxazolines, followed by radical copolymerization with vinylidene fluoride (VDF). A series of MAF-POx macromonomers with number-average molar masses ( M n ) ranging from 200 to 1200 g·mol –1 were successfully synthesized and characterized by 1 H and 19 F NMR spectroscopy as well as MALDI-TOF mass spectrometry. The subsequent graft (statistical) copolymerization was optimized by varying the [VDF]/[MAF-POx] initial molar ratio, the initiator type (peroxide or persulfate), and the reaction conditions. The incorporation of sodium trifluoromethanesulfinate enabled the introduction of CF 3 end-groups, providing a useful probe for molar mass assessment by 19 F NMR. The resulting PVDF- g -POx copolymers were obtained in yields reaching 62% and exhibited number-average molar masses up to 17,000 g·mol –1 . The copolymer compositions were tunable via the feed ratio considering that VDF was more reactive than MAF-POx. Thermal analysis revealed that the incorporation of POx side chains slightly reduced the thermal stability compared to that of pristine PVDF. Differential scanning calorimetry highlighted melting temperatures ranging between 116 and 168 °C, depending on composition and molar mass, while the copolymers containing less than 70 mol % VDF were amorphous.