Tailoring bulk and surface grafting of poly(acrylic acid) in electron-irradiated PVDF

Abstract

International audienceEndowing conventional hydrophobic poly(vinylidene fluoride) (PVDF) films with hydrophilic properties was conducted using electron beam irradiation. Grafting of acrylic acid (AA) in/onto pre-irradiated PVDF films was investigated. Reaction parameters, monomer concentration and inhibitor concentration were examined. Radiation grafted films (PVDF-g-PAA) were synthesized with various grafting yields ranging from 12 to 130 wt % in presence of Mohr's salt (25 wt %). Below 80 wt % of monomer concentration, the degree of swelling was found to increase with the grafting yield. The PAA was arranged randomly in all PVDF matrix (grafting through). Above 80 wt % of monomer concentration, the PAA was grafted only onto the surface of PVDF films leading to a highly dense layer of PAA. Grafting through or surface grafting processes were achieved by varying the water fraction in the initial monomer solution. Water molecule acts not only as a carrier for the monomer but also as a plasticizer expanding the film in the three dimensions. Evidences of grafting through and surface grafting were produced using FTIR in ATR mode, SEM coupled to X-ray detection and XPS. An accurate quantification of AA units was possible up to the micromole via a Cu 2C –EDTA complex analyzed by UV–vis spectroscopy.

Grafting of acrylic acid‐co‐itaconic acid onto ePTFE and characterization of water uptake by the graft copolymers

“…7 We therefore attribute the 287 eV peak to CHACF n grafting points where the graft copolymers are bonded to fluorinated carbon atoms on the ePTFE surface. 36,37 This assignment is in agreement with this peak being of similar intensity for all the samples and the expected similar number of surface graft sites for all the samples as a result of using a constant radiation dose. …”

“…On the other hand, Pulat and Eski 19 have shown that Q e values of cross linked P(AA-co-IA) hydrogels are very strongly dependent on pH, and that while at pH 5 2 a hydrogel with X AA 5 0.83 swelled to a greater extent than a pure PAA hydrogel, the order was reversed at pH 5 4, with the crossover at about pH 5 3. Furthermore, Pulat and Eski 19 have reported the equilibrium swelling of a series of P(AA-co-IA) hydrogels swollen in Britton-Robinson solution (pH 7.4) at 37 C and found that the copolymer hydrogels, which ranged in AA mole fraction from 0.66 to 1.00, swelled to a much smaller extent (fewer water molecules per hydroxyl group) than an PAA hydrogel prepared with the same cross linker concentration and this result correlates with our findings (see Table IV). The number of water molecules per carboxyl group for the samples given in Table IV are, however, smaller than those calculated from Katime and Rodriguez's data.…”

“…Curve fitting to the envelope, demonstrated in Figure 9(b,d), showed the presence of four nonfluorinated carbon components in the spectra; COO at 289 eV, CACOO at 286 eV, CAC at 285 eV, and a small CAO or CHACF n peak at 287 eV. 27,36,37 The latter peak was always of small intensity and observed to have approximately the same intensity relative to the total area of all the carbon peaks in the C1s spectrum. The areas of each of the nonfluorinated carbon peaks in the C1s spectra were calculated relative to the total area of these peaks, and the fractional areas Figure 6.…”

“…Water uptake was obtained by immersing untreated and grafted ePTFE membranes in water overnight at 25 C or in PBS solution at 37 C. The samples were removed from the water and filter paper was used to remove any surface water before the sample weight was determined. The equilibrium water uptake, Q e , was calculated using eq.…”

Surface characteristics and blood compatibility of PVDF/PMMA membranes

“…However, PVDF is a hydrophobic polymer without any functional groups to promote cell adhesion on surface. Therefore, surface modification was widely applied to PVDF membranes to extend their applications as biomaterials [5][6][7][8][9][10].…”