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Tailoring Pore Size and Chemical Interior of near1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal

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ABSTRACT

A triazine based disc shaped moleculewith two hydrolyzable units,imine and ester groups, was polymerized via acyclic diene metathesisin the columnar hexagonal (Colhex) LC phase. Fabricationof a cationic nanoporous polymer (pore diameter ∼1.3 nm) linedwith ammonium groups at the pore surface was achieved by hydrolysisof the imine linkage. Size selective aldehyde uptake by the cationicporous polymer was demonstrated. The anilinium groups in the poreswere converted to azide as well as phenyl groups by further chemicaltreatment, leading to porous polymers with neutral functional groupsin the pores. The pores were enlarged by further hydrolysis of theester groups to create ∼2.6 nm pores lined with −COONasurface groups. The same pores could be obtained in a single stepwithout first hydrolyzing the imine linkage. XRD studies demonstratedthat the Colhex order of the monomer was preserved afterpolymerization as well as in both the nanoporous polymers. The porousanionic polymer lined with −COOH groups was further convertedto the −COOLi, −COONa, −COOK, −COOCs,and −COONH4 salts. The porous polymer lined with−COONa groups selectively adsorbs a cationic dye, methyleneblue, over an anionic dye.

No MeSH data available.


(a) Monitoring adsorptionof the cationic dye, MB (10 μM),by the −COONa functionalized anionic pores of Pore-COONa, inaqueous medium using UV/vis absorption spectroscopy and (b) the plotof absorbance at 665 nm versus time. The inset in parts a and b showingthe color of the porous polymer, Pore-COONa and MB solution beforeand after adsorption experiment, respectively. (c) UV/vis absorptionspectra of the anionic dye, SF, solution before and after exposureto Pore-COONa. (d) Selective adsorption of the cationic dye, MB, overthe anionic dye, SF, by Pore-COONa was monitored by the UV/vis spectroscopy.The inset in part d showing the color of the [MB (20 μM) + SF(30 μM)] solution before and after adsorption by Pore-COONa.
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fig6: (a) Monitoring adsorptionof the cationic dye, MB (10 μM),by the −COONa functionalized anionic pores of Pore-COONa, inaqueous medium using UV/vis absorption spectroscopy and (b) the plotof absorbance at 665 nm versus time. The inset in parts a and b showingthe color of the porous polymer, Pore-COONa and MB solution beforeand after adsorption experiment, respectively. (c) UV/vis absorptionspectra of the anionic dye, SF, solution before and after exposureto Pore-COONa. (d) Selective adsorption of the cationic dye, MB, overthe anionic dye, SF, by Pore-COONa was monitored by the UV/vis spectroscopy.The inset in part d showing the color of the [MB (20 μM) + SF(30 μM)] solution before and after adsorption by Pore-COONa.

Mentions: The anionic poresin Pore-COONa are likely to selectively adsorb cationic dyes. To checkthis hypothesis, adsorption of cationic and anionic dyes was studied.Methylene blue (MB), a cationic dye, was found to be adsorbed fromits aqueous solution when Pore-COONa was immersed in 10 μM aqueoussolution of MB, 1.5 mL. Dye adsorption was monitored by recordingUV/vis spectra of the solution at different time intervals (Figure 6a). MB was adsorbedrapidly by the porous polymer, turning the solution from deep blueto nearly colorless, while the porous polymer became bluish (Figures 6a and 6b, insets), adsorption reached a plateau within 1 h as determinedfrom the decrease of the absorption intensity at 665 nm (Figure 6b). After saturationwith MB from a 10 μM aqueous solution over 12 h, approximately13% of the −COONa groups was associated with a dye molecule(Figure S8).


Tailoring Pore Size and Chemical Interior of near1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal
(a) Monitoring adsorptionof the cationic dye, MB (10 μM),by the −COONa functionalized anionic pores of Pore-COONa, inaqueous medium using UV/vis absorption spectroscopy and (b) the plotof absorbance at 665 nm versus time. The inset in parts a and b showingthe color of the porous polymer, Pore-COONa and MB solution beforeand after adsorption experiment, respectively. (c) UV/vis absorptionspectra of the anionic dye, SF, solution before and after exposureto Pore-COONa. (d) Selective adsorption of the cationic dye, MB, overthe anionic dye, SF, by Pore-COONa was monitored by the UV/vis spectroscopy.The inset in part d showing the color of the [MB (20 μM) + SF(30 μM)] solution before and after adsorption by Pore-COONa.
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fig6: (a) Monitoring adsorptionof the cationic dye, MB (10 μM),by the −COONa functionalized anionic pores of Pore-COONa, inaqueous medium using UV/vis absorption spectroscopy and (b) the plotof absorbance at 665 nm versus time. The inset in parts a and b showingthe color of the porous polymer, Pore-COONa and MB solution beforeand after adsorption experiment, respectively. (c) UV/vis absorptionspectra of the anionic dye, SF, solution before and after exposureto Pore-COONa. (d) Selective adsorption of the cationic dye, MB, overthe anionic dye, SF, by Pore-COONa was monitored by the UV/vis spectroscopy.The inset in part d showing the color of the [MB (20 μM) + SF(30 μM)] solution before and after adsorption by Pore-COONa.
Mentions: The anionic poresin Pore-COONa are likely to selectively adsorb cationic dyes. To checkthis hypothesis, adsorption of cationic and anionic dyes was studied.Methylene blue (MB), a cationic dye, was found to be adsorbed fromits aqueous solution when Pore-COONa was immersed in 10 μM aqueoussolution of MB, 1.5 mL. Dye adsorption was monitored by recordingUV/vis spectra of the solution at different time intervals (Figure 6a). MB was adsorbedrapidly by the porous polymer, turning the solution from deep blueto nearly colorless, while the porous polymer became bluish (Figures 6a and 6b, insets), adsorption reached a plateau within 1 h as determinedfrom the decrease of the absorption intensity at 665 nm (Figure 6b). After saturationwith MB from a 10 μM aqueous solution over 12 h, approximately13% of the −COONa groups was associated with a dye molecule(Figure S8).

View Article: PubMed Central - PubMed

ABSTRACT

A triazine based disc shaped moleculewith two hydrolyzable units,imine and ester groups, was polymerized via acyclic diene metathesisin the columnar hexagonal (Colhex) LC phase. Fabricationof a cationic nanoporous polymer (pore diameter ∼1.3 nm) linedwith ammonium groups at the pore surface was achieved by hydrolysisof the imine linkage. Size selective aldehyde uptake by the cationicporous polymer was demonstrated. The anilinium groups in the poreswere converted to azide as well as phenyl groups by further chemicaltreatment, leading to porous polymers with neutral functional groupsin the pores. The pores were enlarged by further hydrolysis of theester groups to create ∼2.6 nm pores lined with −COONasurface groups. The same pores could be obtained in a single stepwithout first hydrolyzing the imine linkage. XRD studies demonstratedthat the Colhex order of the monomer was preserved afterpolymerization as well as in both the nanoporous polymers. The porousanionic polymer lined with −COOH groups was further convertedto the −COOLi, −COONa, −COOK, −COOCs,and −COONH4 salts. The porous polymer lined with−COONa groups selectively adsorbs a cationic dye, methyleneblue, over an anionic dye.

No MeSH data available.