Retainment of pore connectivity in membranes prepared with vapor-induced phase separation

Surface anti-biofouling control of PEGylated poly(vinylidene fluoride) membranes via vapor-induced phase separation processing

“…Again, the final morphologies also depend on the choice of the other parameters. However, retainment of pore connectivity and formation of porous top-layers are reported for RH controlled to values around 70% [22,25]. Based on these previously reported works and on the fact that the exposure time to vapors was long, which could have affected pore coalescence and led to a denser top-layer, the relative humidity inside the VIPS chamber had to be low and was set to 70%.…”

“…Yet, the slowness of mass transfers at the gas-liquid interface allows an outstanding control and tuning of membrane formation as long as the important parameters are well controlled and properly chosen [17][18][19][20][21][22]. This control of mass transfers is evidenced in literature by a whole set of possible morphologies such as cellular [23], nodular [24] and bicontinuous [25]. In addition, the control of membrane structuring is also critical when it comes to low-biofouling membrane: the surface grafting densities of PEO chains onto the hydrophobic base must be tuned in order to obtain a PEGylated membrane surface with biofouling-resistant characteristics.…”

Programmable Macroporous Photonic Crystals Enabled by Swelling‐Induced All‐Room‐Temperature Shape Memory Effects

“…[65] For liquid acetone with γ = 25.2 mN m −1 and cosθ ≈ 1 (as acetone wets the copolymer), the minimum P c , which occurs at the end of the evaporation process (i.e., when r reaches the maximum and equals the radius of the macropores), is calculated to be ≈0. [66,67] To gain fundamental insights into the effects of the solvent evaporation rate on the unconventional "cold" programming process, we modeled the copolymer swelling process as a simplified 1D solvent diffusion problem using Fick's second law. Higher P c triggered at the beginning stage of the droplet evaporation from the macropores can easily surpass the reduced Young's modulus of the solvent-swollen copolymer, leading to the temporary, deformed configuration of the macropores.…”

Influence of solvent composition and non-solvent activity on the crystalline morphology of PVDF membranes prepared by VIPS process and on their arising mechanical properties

“…As we wanted to avoid the predominance of solvent evaporation compared to the other (nonsolvent penetration), 70% was chosen as the lowest value for RH. Various works have shown for several polymers, including PVDF, that structures can be tuned and drastically affected by other parameters for a constant humidity set to 70% [9,23]. As for the upper boundary, it was set to 95%.…”