Thermoresponsive Gating Characteristics of Poly(<i>N</i>-isopropylacrylamide)-Grafted Porous Poly(vinylidene fluoride) Membranes

Li, Yan; Chu, Liang‐Yin; Zhu, Jiahua; Wang, Haidong; Xia, Siqing; Chen, Wen‐Mei

doi:10.1021/ie034334j

Cited by 82 publications

(56 citation statements)

References 20 publications

(35 reference statements)

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“…This is consistent with our previous investigations carried out with different substrates and different analysis methods. [25][26][27][28][29] The above results confirm that, by using the polymerization method in the study, the functional polymer was grafted on both the outer surfaces of the membrane and the inner surfaces of the membrane pores. Figure 4 shows XPS spectra of an ungrafted nylon-6 membrane, a PNG grafted nylon-6 membrane with…”

Section: Componential and Morphological Analyses Of Grafted Membranessupporting

confidence: 60%

“…First, poly(N-isopropylacrylamide-co-glycidyl methacrylate) (poly(NIPAM-co-GMA), abbreviated to PNG) linear chains were grafted onto porous nylon-6 membrane substrates by using plasma-graft pore-filling polymerization, according to methods described previously. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Then, ethylenediamine When the operation temperature is at T 1 , a temperature lower than the lower critical solution temperature (LCST) of PNIPAM, grafted PNIPAM chains are swollen and hydrophilic, and one of two enantiomers is captured by b-CD molecules during the permeation. When the temperature is increased to T 2 , a value higher than the LCST, grafted PNIPAM chains become shrunken and hydrophobic and at the same time the association constant between b-CD and captured molecules decreases; as a result, decomplexation occurs, and thus the enantiomers are separated and the membrane is regenerated.…”

Section: Strategies For the Fabrication And Processing Of The Membranementioning

confidence: 99%

“…Similar results have been reported in our previous work. [25,26] When the grafting yield of PNIPAM was lower, the diffusional coefficient of solute across the membrane was higher at temperatures above the LCST than that below the LCST, owing to the membrane pores being controlled ''open'' by the shrinking of grafted PNIPAM, which provided more space within the pores to allow the solute to diffuse through at T above the LCST; On the other hand, when the grafting yield of PNIPAM was higher, the diffusional …”

Section: Permeation Of Dl-tryptophan Through Png-cd-grafted Membranesmentioning

confidence: 99%

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A Thermoresponsive Membrane for Chiral Resolution

Yang

Chu

Wang

et al. 2008

Adv Funct Materials

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102

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A novel thermoresponsive membrane for chiral resolution with high performance has been developed. The membrane exhibits chiral selectivity based on molecular recognition of beta‐cyclodextrin (β‐CD) and thermosensitivity based on the phase transition of poly(N‐isopropylacrylamide) (PNIPAM). Linear PNIPAM chains were grafted onto porous nylon‐6 membrane substrates by using a plasma‐graft pore‐filling polymerization method; the chains thus acted as microenvironmental adjustors for β‐CD molecules. β‐CD moieties were introduced into the linear PNIPAM chains by a chemical grafting polymerization method and acted as chiral selectors. The phase transition of grafted PNIPAM chains affects the microenvironment of β‐CD molecules and, thus, the association between β‐CD and guest molecules. The chiral selectivity of the prepared thermoresponsive membranes in chiral resolution operated at temperature below the lower critical solution temperature (LCST) of PNIPAM is higher than that of membranes with no thermosensitivity. Furthermore, the decomplexation ratio of enantiomer‐loaded thermoresponsive membranes in decomplexation at temperatures above the LCST is much higher than that of membranes with no thermosensitivity. Thus, by simply changing the operation temperature, high, selective chiral resolution and efficient membrane regeneration are achieved. The proposed membrane provides a new and efficient way to solve the difficult decomplexation problem of chiral solid membranes, which is highly attractive for chiral resolution.

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Section: Componential and Morphological Analyses Of Grafted Membranessupporting

confidence: 60%

Section: Strategies For the Fabrication And Processing Of The Membranementioning

confidence: 99%

Section: Permeation Of Dl-tryptophan Through Png-cd-grafted Membranesmentioning

confidence: 99%

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A Thermoresponsive Membrane for Chiral Resolution

Yang

Chu

Wang

et al. 2008

Adv Funct Materials

Self Cite

102

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“…Several parameters such as the grafting yield and the morphological location of grafted polymeric gates, the molecular size of permeants and the initial membrane pore size have been verified to have significant influences on the stimuli-responsive characteristics of the gating membranes [5,9,27,34,36,40].…”

Section: Introductionmentioning

confidence: 99%

Gating Characteristics of Thermo‐Responsive Membranes with Grafted Linear and Crosslinked Poly(N‐isopropylacrylamide) Gates

et al. 2009

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Thermo-responsive porous membranes with grafted linear and crosslinked poly(N-isopropylacrylamide) (PNIPAM) gates are successfully prepared at temperatures above and below the lower critical solution temperature (LCST) of PNIPAM by using a plasma-induced grafting polymerization method, and the effects of operation pressure and grafting temperature on the thermo-responsive gating characteristics of the prepared membranes are investigated systematically. The fluxes of water through the grafted membranes increase simply with increasing the operation pressure no matter whether the environmental temperature is 40°C or 25°C. Under high operation pressure (e.g., higher than 0.14 MPa), the grafted linear PNIPAM gates deform to a certain extent, whereas the grafted crosslinked PNIPAM gates do not deform. For both membranes with grafted linear and crosslinked PNIPAM gates, the membranes prepared at 25°C (below the LCST of PNIPAM) show larger thermo-responsive gating coefficients than those prepared at 40°C (above the LCST of PNIPAM), which results from different distributions of grafted PNIPAM gates in the membrane pores. When the PNIPAM gates are grafted at 25°C, the grafted layer near the membrane surface is much thicker than that inside the membrane pores; on the other hand, when the PNI-PAM gates are grafted at 40°C, the grafted layer is homogeneously formed throughout the whole pore length. Both linear and crosslinked grafted PNIPAM gates in the membrane pores exhibit stable and repeatable thermo-responsive "open-close" switch performances under the operation pressure of 0.26 MPa. The results in this study provide valuable guidance for designing, fabricating, and operating thermo-responsive gating membranes with desirable performances.

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“…The concentration of VB 12 in the receptor cell was analyzed spectrophotometrically at 361 nm using a UV-VIS recording spectrophotometer. The diffusion coefficient of solute across the membrane can be calculated using the following equation, derived from Fick's first law of diffusion [2,3,6]:…”

Section: Measurement Of the Diffusional Permeability Of Vb 12 Throughmentioning

confidence: 99%

Thermo-Responsive Membranes with Cross-linked Poly(N-Isopropyl-acrylamide) Hydrogels inside Porous Substrates

Chu

et al. 2006

Chem. Eng. Technol.

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Thermo-responsive membranes were prepared by fabricating cross-linked poly(N-isopropylacrylamide) (PNIPAM) hydrogels inside the pores of porous Nylon-6 (N6) membranes by the free radical polymerization method. SEM micrographs of the prepared membranes showed that PNIPAM hydrogels were filled uniformly throughout the entire thickness of the porous N6 membranes. Both PNIPAM-filled N6 membranes prepared at 60°C and at 25°C exhibited significant reversible and reproducible thermo-responsive diffusional permeability. When the environmental temperature remained constant, the diffusional coefficient of vitamin B 12 (VB 12 ) across the PNIPAM-filled N6 membrane prepared at 25°C was ca. twice the value of that prepared at 60°C due to different filling yields. The thermo-response factor of the membrane prepared at 25°C was higher than that prepared at 60°C. The 3-dimensional interpenetrating network structure of the cross-linked PNIPAM hydrogels inside the N6 porous substrates could effectively ensure a repeatable thermo-responsive permeation performance.

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Thermoresponsive Gating Characteristics of Poly(N-isopropylacrylamide)-Grafted Porous Poly(vinylidene fluoride) Membranes

Cited by 82 publications

References 20 publications

A Thermoresponsive Membrane for Chiral Resolution

A Thermoresponsive Membrane for Chiral Resolution

Gating Characteristics of Thermo‐Responsive Membranes with Grafted Linear and Crosslinked Poly(N‐isopropylacrylamide) Gates

Thermo-Responsive Membranes with Cross-linked Poly(N-Isopropyl-acrylamide) Hydrogels inside Porous Substrates

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