Poly(dimethylsiloxane-urethane) membranes: Effect of hard segment in urethane on gas transport properties

Polyurethane–poly(vinylidene fluoride) (PU–PVDF) thin film composite membranes for gas separation

“…Consequently the active layer of the membrane could be considered as a multiphase morphological structure which might produce torturous paths with less resistance for diffusing penetrants. Similar morphological structures of polyurethanes have also been reported in literature [16,17]. Furthermore, the physical crosslinking in the polyurethane restricted the swelling ratio of the soft segment, and resulted in a low additional permeation of permanent gases upon swelling, leading to an enhanced selectivity.…”

“…However, ideal selectivities for above gas pairs were still lower than PEG-based PU with the small amount of PDMS {PUU (PEG/PDMS)} due to PEG's intrinsic properties. Park et al [16] and Madhavan and Reddy [17] believed that the incorporation of PDMS results in the phase separation in both hard and soft segments due to the difference of solubility parameter and the dispersed PDMS phases, which produces a more tortuous route for diffusing molecules. On the other hand, PU-PVDF composite membrane in this work showed higher oxygen selectivity with lower nitrogen permeance compared with PDMS-PVDF composite membrane [20].…”

“…The hard segment alternates along with soft segment, which produces distinguishing physical and mechanical properties for polyurethane. Many researchers have been investigating segmented polyurethane as a new material to improve the permselectivity for gas separation such as VOCs or CO 2 from N 2 ,H 2 S/CH 4 and O 2 /N 2 [10][11][12][13][14][15][16][17]. The structure-gas transport property correlations of those PU film membranes with a variety of singular or mixed soft segments elucidate that the gas permselectivity mainly depends on the contents and types of soft segments as well as their molecular weights.…”

“…The combination of polysiloxane with polyurethane has attracted special attention due to the advantages of not only better thermal stability and high flexibility at low temperatures but also better mechanical strength and abrasion 0376 characteristic contributed by polyurethane. Park et al [16] reported the gas transport properties of mixed polysiloxane/polyether soft segment urethane urea film membranes, and Madhavan and Reddy [17] showed the effect of urethane type and content for hard segment on gas performance in poly(dimethylsiloxane-urethane) film membranes. They found that PDMS-based PU thin film membranes performed higher selectivities with reasonable permeabilities compared to no-filler PDMS for O 2 /N 2 and CO 2 /N 2 separations.…”

Structure-Gas Transport Property Relationships of Poly(dimethylsiloxane-urethane) Nanocomposite Membranes

“…On the other hand, polyurethanes and polyimides are promising materials that have good mechanical properties and better gas selectivities (Huang and Lai, 1995;Yoshino et al, 2000;Yang et al, 2002). In our previous www.intechopen.com Structure-Gas Transport Property Relationships of Poly(dimethylsiloxane-urethane) Nanocomposite Membranes 201 work, we have reported that the PDMS based polyurethanes show better gas separation process (Madhavan and Reddy, 2006). However, it was observed that increase in PDMS content was associated with a decrease in the mechanical properties and gas selectivities.…”