P (VDF-co-CTFE)-g-P2VP amphiphilic graft copolymers: Synthesis, structure, and permeation properties

A series of amphiphilic graft copolymers of poly (vinylidene fluoride-co-chlorotrifluoroethylene)-g-poly(2-vinyl pyridine), P (VDF-co-CTFE)-g-P2VP, with different degrees of P2VP grafting (from 26.3 to 45.6 wt%) was synthesized via one-pot atom transfer radical polymerization (ATRP). The amphiphilic properties of P (VDF-co-CTFE)-g-P2VP graft copolymers allowed itself to self-assemble into nanoscale structures. P (VDF-co-CTFE)-g-P2VP graft copolymers were introduced into neat P (VDF-co-CTFE) as additives to form blending membranes. When two different solvents, N-methyl-2-pyrrolidone (NMP) and dimethylformamide (DMF), were used, specific organized crystalline structures were observed only in the NMP systems. P (VDF-co-CTFE)-g-P2VP played a pivotal role in controlling the morphology and pore structure of membranes. The water flux of the membranes increased from 57.2 to 310.1 L m⁻² h⁻¹ bar⁻¹ with an increase in the PVDF-co-CTFE-g-P2VP loading (from 0 to 30 wt%) due to increased porosity and hydrophilicity. The flux recovery ratio (FRR) increased from 67.03% to 87.18%, and the irreversible fouling (R_ir) decreased from 32.97% to 12.82%. Moreover, the pure gas permeance of the membranes with respect to N₂ was as high as 6.2 × 10⁴ GPU (1 GPU = 10^–6 cm³[STP]/[s cm² cmHg]), indicating their possible use as a porous polymer support for gas separation applications.