Gas separation using membranes comprising polybenzoxazoles prepared by thermal rearrangement
a technology of benzoxazole and polybenzoxazole, which is applied in the direction of membranes, dispersed particle separation, separation processes, etc., can solve the problems of poor practical application suitability of glassy polymers, low selectivity of tr--pbo for small gases such as hydrogen and helium, etc., and achieve the effect of thermal rearrangemen
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example 1
Preparation of polybenzoxazole (TR-β-PBO) separation membrane
[0098]TR-β-PBO represented by Formula 3 below was prepared through the following reaction.
[0099]2,2′-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (bisAPAF, 3.663 g, 10 mmol) and NMP (15.06 mL) were charged into a 100 mL 3-neck flask under nitrogen purging and the mixture was placed into an ice bath at 0° C. Subsequently, a solution of propylene oxide (PO, 0.3 mL) and terephthaloyl chloride (TCL, 2.030 g, 10 mmol) in NMP (8.35 mL) was added to the mixture and then allowed to proceed for 2 hours.
[0100]The resulting mixture was stirred for 12 hours under an inert atmosphere to obtain a viscous poly(hydroxyamide) (PHA) solution.
[0101]The solution was cast onto a glass substrate and dried at 100° C. for one hour and at 200° C. for 10 hours to remove the solvent, thereby obtaining a PHA precursor membrane.
[0102]The PHA precursor membrane was thermally treated at 350° C. at a heating rate of 5° C. / min for one hour under an Ar a...
experimental example 1
Thermogravimetric Analysis / Mass Spectroscopy (TGA-MS)
[0108]The PHA precursor membrane of Example 1 and the HPI precursor membrane of Comparative Example 1 were subjected to TGA-MS to confirm dehydration and CO2 evolution. The TGA-MS for each precursor membrane was carried out using TG 209 F1 Iris and QMS 403C Aeolos (NETZSCH, Germany). The results thus obtained are shown in FIG. 1.
[0109]FIG. 1 is a graph showing TGA-MS results of the PHA precursor membrane of Example 1 and the HPI precursor membrane of Comparative Example 1.
[0110]As can be confirmed from FIG. 1, the PHA precursor membrane of Example 1 undergoes weight loss at 250 to 350° C. (represented by reference numeral a′ in FIG. 1) corresponding to the temperature at which thermal conversion from PHA to TR-β-PBO occurs, and MS peaks indicating dehydration (removal of H2O) are plotted at 300° C. (represented by reference numeral b in FIG. 1). On the other hand, it can be confirmed from FIG. 1 that the HPI precursor membrane of ...
experimental example 2
FT-IR analysis
[0112]The PHA precursor membrane and TR-β-PBO membrane of Example 1, and HPI precursor membrane and TR-α-PBO membrane of Comparative Example 1 were subjected to FT-IR analysis to confirm characteristic peaks. FT-IR spectra were obtained using a Nicolet Magna IR 860 instrument (thermo Nicolet, Madison, Wis., USA). The results thus obtained are shown in FIGS. 2(a) and 2(b).
[0113]FIG. 2(a) is FT-IR spectra of the HPI precursor membrane and the TR-α-PBO membrane of Comparative Example 1. FIG. 2(b) is FT-IR spectra of the PHA precursor membrane and TR-β-PBO membrane of Example 1.
[0114]As can be seen from FIGS. 2(a) and 2(b), broad bands (a and f) by O—H stretching of HPI and PHA are observed at 3,700 to 2,500 cm−1.
[0115]As apparent from FIG. 2(a), the HPI precursor membrane shows characteristic absorption bands of imide groups at 1,729 cm−1 (C═O stretching, c) and 1,781 cm−1 (C═O stretching, b), and as apparent from FIG. 2(b), the PHA precursor membrane shows characteristic...
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