Bioinspired Poly(vinylidene fluoride) Membranes with Directional Release of Therapeutic Essential Oils

Abstract

Here, the morphology of polypore fungi has inspired the fabrication of poly(vinylidene fluoride) (PVDF) membranes with dual porosity by nonsolvent-induced phase separation (NIPS). The fruiting body of such microorganisms is constituted of two distinct regions, finger- and sponge-like structures, which have been successfully mimicked by controlling the coagulation bath temperature during the NIPS process. The use of water at 10 °C as coagulant resulted in membranes with the highest finger-like/sponge-like ratio (53% of the total membrane thickness), while water at 90 °C allowed the formation of macrovoid-free membranes. The microchannels and the asymmetric porosity were used to enhance the oil sorption capacity of the PVDF membranes and to achieve directional release of therapeutic essential oils. These PVDF membranes with easily tuned asymmetric channel-like porosity and controlled pore size are ideal candidates for drug delivery applications.

Geometry-Induced Asymmetric Vanadium-Ion Permeation of PVDF Membranes and Its Effect on the Performance of Vanadium Redox Flow Batteries

“…In terms of a geometric exclusion effect, 35 the effective ion mobility (u eff ) through a porous membrane is related to geometric factors, u eff ∼ θ(1 − λ) 2 /τ; where τ is the tortuosity, λ = r ion /r pore is the ratio of the mobile ion radius (r ion ) to the pore radius (r pore ), and θ is the porosity of the membrane. Considering that the porosity (θ = 30−40%) is not highly affected by T c and morphologies (Figure S2), 30,34 u eff through a membrane having a higher fraction of SL pore is diminished due to the smaller pore size and higher tortuosity of SL pores compared to FL pores, and resulted in increased resistance as T c is increased as shown in Figure 2.…”

“…33 Interestingly, the physical gelation causes delayed demixing, but gives sufficient time for FL pore evolution at a low T c . 30 At high T c , however, the PVDF precipitation kinetics is enhanced, and fast enough, yielding a bicontinuous morphology via spinodal decomposition. 34 As a result, the membranes manufactured at T c = 30 and 40 °C show clear asymmetrical morphologies along the thickness direction as shown in Figure 1.…”

“…Note that there are two directional effect studies of asymmetric membranes, but the asymmetries in those studies originated from the dense layer on the porous substrate and not from purely asymmetric pores. 25,26 In other diffusion-related applications, such as Li-ion battery, 27 gas separation, 28 osmotic processes, 29 oil filtration, 30 and microfluidic pump, 31 the geometric asymmetric membranes show different performances due to the asymmetric ion or molecular permeation depending on the permeation directions: (1) from the side with narrow pores to the side with wide pores; (2) from the side with wide pores to the side with narrow pores. For example, Kim et al employed a terpyridine-functionalized cellulose nanoporous thin layer on an electrospun macroporous thick mat as a separator membrane to suppress the permeation of manganese ions (Mn 2+ ) from a LiMn 2 O 4 cathode to a Li metal anode.…”

3D Arrays of Super-Hydrophobic Microtubes from Polypore Mushrooms as Naturally-Derived Systems for Oil Absorption

“…The fruiting bodies of G. applanatum consisted of a large number (30–40 pores/mm 2 ) of long (up to 20 mm [21,22]) and regular tubes (Figure 1b). The apertures of the tubes from the underside of the fungus had a circular to ovoid shape with a diameter ranging between 80 to 100 µm (Figure 1c,d).…”

Polymeric Carriers Designed for Encapsulation of Essential Oils with Biological Activity

“…Poly(vinylidene fluoride) (PVDF) membranes with dual porosity were prepared through a technique mimicking polypore fungi obtained by non-solvent-induced phase separation [ 161 ]. The membranes were further charged with tea tree EO, to confer antimicrobial properties.…”