Poly(vinylidene fluoride)-Based Graft Copolymeric Protein Binding Porous Sorbent Films for Immobilized Metal Ion Chromatography

Highly efficient protein immobilization porous sorbent films (PSFs) have been developed using poly(vinylidene fluoride) (PVDF)-based graft copolymers via an immobilized metal ion affinity chromatography approach. Atom transfer radical polymerization was employed to graft random copolymeric chains of glycidyl methacrylate (GMA) and diethylene glycol methyl ether methacrylate (DEGMEM)/polyethylene glycol methyl ether methacrylate (PEGMEM) from a PVDF macroinitiator. X-ray photoelectron spectroscopy revealed that halogen exchange occurs on the PVDF backbone prior to grafting, with significantly higher substitution of fluorine by chlorine using a CuCl catalyst (∼8% of >CF2 units) compared to bromine substitution with CuBr (∼1.5%), attributed to the greater thermodynamic stability of C–Cl bonds. The graft copolymers were fabricated into porous films via an immersion–precipitation technique and subsequently functionalized, through epoxy ring opening to introduce iminodiacetic acid–Cu(II) complexes for selective binding of histidine-containing proteins like bovine serum albumin (BSA) or myoglobin (Mb). The presence of hydrophilic DEGMEM/PEGMEM segments effectively minimized nonspecific protein adsorptions. The PSFs exhibited rapid adsorption kinetics, reaching saturation within 10 min at a flow rate of 1.5 mL min–1 and a high BSA binding capacity (∼0.85 mg cm–2; ∼43 mg cm–3). Adsorption isotherms confirmed monolayer coverage, while >95% protein recovery was achieved over eight adsorption–desorption cycles, demonstrating excellent reusability.