Zwitterionic Poly(vinylidene fluoride) Graft Copolymer with Unexpected Fluorescence Property

Abstract

Recently, there has been a growth of research on the nonconjugated polymer exhibiting fluorescence property and it would be exciting if fluorescence property is developed in zwitterionic polymers because of their good water solubility. Poly(vinylidene fluoride) (PVDF) grafted with poly(dimethyl amino ethyl methacrylate) (PDMAEMA) is fractionated and a highly water-soluble fraction (PVDM-1) is quaternized with 1,3-propane sultone, producing a zwitterionic polymer, PVDF-g-PDMAEMA-sultone (PVDMS). PVDM-1 shows the fluorescence property with very low quantum yield (1%) in water, but on quaternization, fluorescence quantum yield increases to 8%. Transmission electron microscopy results indicate that the PVDM-1 cast from water has vesicular morphology, whereas PVDMS exhibits aggregated vesicular morphology. The 1 H NMR spectra indicate the presence of 72 mol % DMAEMA in PVDM-1 wherein 66% of -NMe2 groups is quaternized upon postpolymerization modification. PVDM-1 exhibits absorption peaks at 210, 276, and 457 nm with a hump at 430 nm, whereas PVDMS exhibits two absorption peaks at 203 and 297 nm. PVDM-1 exhibits a broad emission peak at 534 nm, whereas PVDMS exhibits a sharp emission peak at 438 nm. An attempt has been made from density functional theory calculations to shed light on the origin of fluorescence in both PVDM-1 and in the zwitterionic PVDMS. The excitonic decay occurs from the lowest unoccupied molecular orbital (LUMO) of carbonyl group to the highest occupied molecular orbital (HOMO) of tertiary amine group for PVDM-1, whereas in PVDMS, the excitonic transition occurs from the LUMO situated over the quaternary ammonium group to the HOMO located on the electron-rich terminal sulfonate group.

Fluorescence in “Nonfluorescent” Polymers

“…In a very interesting work, Nandi and his co-workers have reported for the first time fluorescence emission from a poly(vinylidene difluoride) (PVDF)-based graft copolymer in aqueous solutions. 58 In this work, synthesis of PVDF- g -PDMAEMA (PVDM-1) is carried out at first using atom-transfer radical polymerization, and then the graft copolymer is fractionated to get a good water-soluble fraction. Subsequently, the product having tertiary amine groups of PDMAEMA-grafted chains is reacted with sultone to obtain a water-soluble zwitterionic graft copolymer (PVDMS).…”

“…This issue was also commented by Nandi and co-workers while working on the emission properties of semicrystalline PVDF-based graft copolymers. 58 Thus, the observed intense emission in films promises their potential application during fabrication of OLEDs or light-conversion films. 15 Apart from the fluorescence emissions, triplet emissions (phosphorescence) from PAN are achieved in the solid state ( Figure 14 III).…”

“…Apart from these, several applications of non-conventional fluorescent polymers have been reported in cell imaging or detection of ionic surfactants. 57 , 58 , 89 …”

Fluorescent Terpolymers via In Situ Allocation of Aliphatic Fluorophore Monomers: Fe(III) Sensor, High‐Performance Removals, and Bioimaging

“…These terpolymers are suitable in four‐in‐one applications, such as “turn‐Off” Fe(III) sensor, superadsorbents, normal and cancer cell‐imaging, and reverse‐INHIBIT logic function. For precise determination of fluorophores and associated mechanism contributing to the intrinsic intense blue and green emissions, density functional theory (DFT), time‐dependent DFT (TDDFT), and natural transition orbital (NTO) analyses have been employed for evaluating wave function overlap (σ he ) and separations (∆ r ) between holes and electrons. Moreover, in vitro bioimaging and cell viability studies of terpolymers have been conducted in normal and cancer cell lines.…”

Crosslink‐Enhanced Emission Effect on Luminescence in Polymers: Advances and Perspectives

“…made nonconjugated poly(vinylidene fluoride) (PVDF) fluorescence active. This was done by quaternization of a highly water‐soluble fraction (PVDM‐1) of PVDF‐g‐poly(dimethyl amino ethyl methacrylate) (PDMAEMA) with 1,3‐propane sultone, and ultimately produced a zwitterionic polymer, PVDF‐g‐PDMAEMA‐sultone (PVDMS) . As illustrated in Figure a, the morphology of PVDM‐1 changed from small vesicles into large crosslinked vesicles of PVDMS due to ionic interactions, and the corresponding QY was greatly increased from 1 % to 8 %.…”