Double Stimuli-Responsive Ultrafiltration Membranes from Polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) Diblock Copolymers

Abstract

We report on the formation of self-supporting, double stimuli-responsive ultrafiltration membranes via the non-solvent-induced phase separation (NIPS) process. The polymers, polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) (PS-b-PDMAEMA), were synthesized via living anionic polymerization in THF using sec-butyllithium as initiator. Two amphiphilic diblock copolymers were used, S(81)D(19)(75) and S(68)D(32)(100). The membranes were cast from mixtures of THF and DMF. The influence of the solvent composition, the "open-time" before immersion into the coagulation bath, and the casting film thickness onto the membrane morphology were thoroughly investigated, and flux values obtained for the different membrane systems were compared. The higher content in hydrophilic polymer for S(68)D(32)(100) resulted in a better compatibility with the nonsolvent bath consisting of water, leading to a slower precipitation and thus an improved control of the phase separation occurring. Under certain conditions, ordered microphase-separated porous morphologies were observed in parts of the membrane cross-section. Further, the "smart" properties of those novel materials are shown for two representative systems. It could be demonstrated that both stimuli for PDMAEMA, pH and temperature, can be reversibly and independently applied in order to significantly change the transmembrane water flux.

Structure Formation of Integral Asymmetric Composite Membranes of Polystyrene‐block‐Poly(2‐vinylpyridine) on a Nonwoven

“…Tailor‐made block copolymer membranes for ultra‐ or microfiltration have attracted increasing interest in the last few years after first demonstration experiments showing different ways of their preparation as composite membranes by solution casting or even integral asymmetric membranes by so‐called phase inversion technique 1–10…”

Asymmetric Membranes from Two Chemically Distinct Triblock Terpolymers Blended during Standard Membrane Fabrication

“…The most widely studied polymer system fabricated to date with this block copolymer self‐assembly and nonsolvent induced phase separation (SNIPS) process is the diblock copolymer, poly(styrene‐ b ‐(4‐vinyl)pyridine) (PS‐ b ‐P4VP, SV). The phase inversion technique was successfully applied to other diblock copolymer systems including poly(styrene‐ b ‐(dimethylaminoethyl) methacrylate) (PS‐ b ‐PDMAEMA), poly(styrene‐ b ‐ethylene oxide) (PS‐ b ‐PEO), poly(styrene‐ b ‐methyl methacrylate) (PS‐ b ‐PMMA), as well as triblock terpolymer systems such as poly(isoprene‐ b ‐styrene‐ b ‐4‐vinylpyridine) (PI‐ b ‐PS‐ b ‐P4VP, ISV), poly(isoprene‐ b ‐styrene‐ b ‐ N,N ‐dimethylacrylamide) (PI‐ b ‐PS‐ b ‐PDMA) and poly(styrene‐ b ‐4‐vinylpyridine‐ b ‐propylene sulfide) (PS‐ b ‐P4VP‐ b ‐PPS, SVPS) …”

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studied polymer system fabricated to date with this block copolymer self-assembly and nonsolvent induced phase separation (SNIPS) process [ 2 ] is the diblock copolymer, poly(styrene-b -(4-vinyl)pyridine) (PS-b -P4VP, SV). The phase inversion technique was successfully applied to other diblock copolymer systems including poly(styreneb -(dimethylaminoethyl) methacrylate) (PS-b -PDMAEMA), [ 3 ] poly(styrene-b -ethylene oxide) (PS-b -PEO), [ 4 ] poly(styreneb -methyl methacrylate) (PS-b -PMMA), [ 5 ] as well as triblock terpolymer systems such as polyEmploying a second component in the casting dope solution, various membrane properties were tailored. For example, the morphology of the top surface layer was tuned by the addition of small organic molecules [ 9 ] and Deviating from the traditional formation of block copolymer derived isoporous membranes from one block copolymer chemistry, here asymmetric membranes with isoporous surface structure are derived from two chemically distinct block copolymers blended during standard membrane fabrication.

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“…studied polymer system fabricated to date with this block copolymer self-assembly and nonsolvent induced phase separation (SNIPS) process [ 2 ] is the diblock copolymer, poly(styrene-b -(4-vinyl)pyridine) (PS-b -P4VP, SV). The phase inversion technique was successfully applied to other diblock copolymer systems including poly(styreneb -(dimethylaminoethyl) methacrylate) (PS-b -PDMAEMA), [ 3 ] poly(styrene-b -ethylene oxide) (PS-b -PEO), [ 4 ] poly(styreneb -methyl methacrylate) (PS-b -PMMA), [ 5 ] as well as triblock terpolymer systems such as poly…”

Hydrophilic polyisophthalamides containing poly(ethylene oxide) side chains: Synthesis, characterization, and physical properties

“…Growing interest has also been observed in developing polymeric materials which contain PEO or ethylene oxide copolymers, as covalently linked sequences or as a permanent additive, for water membranes that exhibit antibiofouling properties 33–42…”