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Reporter：Shao-Fung Chiu
Advisor：Cheng-Ho Chen
Date：2015/12/22
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Introduction
1. Stimuli-responsive polymeric membranes have
attracted much research interest due to the abrupt
property changes in response to small changes in
external stimuli such as temperature, pH, solvent,
chemical species, and photo-irradiation.
2. Comparing with other stimuli, pH sensitivity gives
more choices both for the materials and applying
environment as a novel and powerful technique.
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3. Polyethersulfone (PES) is a well-known polymeric
material. The PES and PES based membranes show
outstanding oxidative, thermal,and hydrolytic
stability as well as good mechanical and filmforming properties.
4. Two random copolymers, P(AN-AA) and
P(AN-MAA),were synthesized via free radical
polymerization, the copolymers were directly blended
with PES to prepare hollow fiber membranes by dry–
wet spinning technique.
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Materials
Acrylic acid
Methyl acrylic acid
Acrylonitrile
N-methyl-2-pyrrollidone (NMP)
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Polyethersulfone
(PES)
Azo-bis-isobutyronitrile
(AIBN)
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Experimental
Synthesis of P(AN-AA)
AN and AA (ratio of 2:3) were dissolved in dioxane with the total
monomer concentration of 30 wt.%.
The initiator, Azo-bis-isobutryonitrile (AIBN) was introduced into
the mixed solution with the weight ratio of 0.3% to the total monomers.
And then the solution was stirred continuously until all reagents were
completely dissolved.
After passing nitrogen to the solution for 15 min, polymerization was
carried out in airtight equipment at 60 °C for 24 h.
The reaction was terminated by ethanol, and then washed several times with
adding ethanol to remove the residual monomers and initiators thoroughly.
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The crude product was washed by hot de-ionized water
until the pH value was neutral.
The final copolymer P(AN-AA) was dried completely at 60 °C
in a vacuum oven for 72 h.
Preparation: Synthesis of P(AN-MAA)
The synthesis of P(AN-MAA) was carried out in the same manner.
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Preparation of pH-sensitive PES hollow fiber membranes
PES and the synthesized copolymers were dissolved in NMP
in a glass reactor equipped with a mechanical stirrer to obtain clear
homogeneous solutions, and the concentration of PES was 20 wt.%.
The two synthesized copolymers were dissolved in NMP
with a concentration of 5 wt.%,respectively.
Five kinds of filters were prepared (HFM-20-0, HFM-AA-0.4,
HFM-AA-0.8, HFM-MAA-0.45, and HFM-MAA-0.9) and the
compositions of the hollow fibers are shown in Table 1.
The polymer solutions were degassed and then used for the
fabrication of pH-sensitive PES hollow fiber membranes by dry–wet
spinning technique.
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Results and discussion
FTIR spectra analysis of copolymers
Fig.1. FT-IR spectrums of copolymers:
(a) P(AN-AA) and (b) P(AN-MAA)
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SEM of the hollow fiber membrane
Fig.2. SEM images of the cross-sections of the PES hollow fiber membranes.
(a) HFM-AA-0.4(0.4 wt.%); (b) HFM-AA-0.8(0.8 wt.%); (c) HFM-MAA-0.45(0.45 wt.%);
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(d) HFM-MAA-0.9,(0.9 wt.%);(e) HFM-20-0. Voltage: 20 kV; magnification:100×.
Membrane water flux as a function of
pH value
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Outline
Introduction
Experimental
Results and discussion
Conclusions
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Conclusions
1. Functional copolymers, P(AN-AA) and P(AN-MAA) were
successfully synthesized via conventional free radical
polymerization by FT-IR
2. The copolymers could be directly blended with PES to prepare
hollow fiber membranes by dry–wet spinning technique.
3. Both of the two copolymer modified PES hollow fiber
membranes showed evident pH sensitivity.
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Thank you for your attention
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