• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6029-6038
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• 2013

In this study we attempt to modify the backbone structure and improve processibility of PBO having high melting and glass transition temperature. A series of aromatic poly(o-hydroxyamide)s(PHAs) were synthesized by direct polycondensaton of diacides containing diimide unit with two types of bis(o-aminophenol)s including 3,3'-dihydroxybenzidine and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. PHAs were studied by FT-IR, $^1H$-NMR, DSC and TGA. PHAs exhibited inherent viscosities in the range of 0.34~0.65 dL/g at $35^{\circ}C$ in DMAc solution. The PHA 1 and 6F-PHA 6, introducing o-phenylene unit in the main chain showed excellent solubilities in aprotic solvents such as NMP etc. However, the PHA 3, having p-phenylene unit was not even dissolved perfectly with LiCl salt. 6F-PHAs were readily soluble at room temperature in aprotic solvents except 6F-PHA 3. But they showed better solubility than that of PHAs. The polybenzoxazoles(PBOs) were quite insoluble in other solvents except partially soluble in sulfuric acid. PBOs exhibited relatively high glass transition temperatures(Tg) in the range of 306~$311^{\circ}C$ by DSC. The maximum weight loss temperature and char yields of PHA3 and 6F-PHA3 showed the highest values of $658^{\circ}C$ and $653^{\circ}C$, 62.6 % and 62.1 %, respectively.

• Journal of the Korean Chemical Society
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• v.16 no.5
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• pp.314-319
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• 1972

N-Methyl-p-aminophenol was polymerized by oxidative couplng in the aqueous iron chelate solution in the presence of oxygen, and black precipitate of oligo-(N-methyl-p-aminophenol) was formed quantitatively. In this oxidative polymerization reaction, methyl group attached to N in the monomer was partly eliminated, and it was clarified by the infrared spectra from the fact that the absorption of ${\delta}\;asym\;CH_3\;1460\;cm^{-1}$ and ${\delta}\;sym\;CH_3\;1380\;cm^{-1}$ in acetone insoluble fraction was much weaker than that in acetone soluble fraction. From Thermo-gravimetric analysis, oligo-(N-methyl-p-aminophenol) showed about 40% weight loss at $600^{\circ}C$ and it was less heat-resistant than oligo (p-aminophenol) that methyl group was not contained. In pyrolysis of oligo-(N-methyl-p-aminophenol) in He atmosphere, monomer N-methyl-p-aminophenol and water were formed, and in the pyrolytic gases, $H_2,\;CO,\;CO_2$ were detected by gas chromatography. From the above facts, to the structural change on oligo-(N-methyl-p-aminophenol) when it was heat-treated, it was considered that original linear structure was partly degraded, and the most of the oligomer was to go in with melt polycondensation to form polymer, and heat-resistant cyclic structure was formed at a time.

• Journal of Life Science
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• v.26 no.5
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• pp.545-554
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• 2016

Hyaluronic acid (HA) is an important macromolecule in medical and pharmaceutical fields. HA is a natural and linear polymer composed of repeating disaccharide units of β-1, 3-N-acetyl glucosamine and β-1, 4-glucuronic acid. This work aimed to confirm the structural characteristics and anti-inflammatory activities of HA and its chemically sulfated-HA. HA was produced from a fed-batch fermentation process using Streptococcus dysgalactiae in a 5 l bioreactor. HA was isolated water-soluble form (HA-WS) and water-insoluble form (HA-WI) from culture medium, and was obtained chemically sulfated-derivative (S-HA) that resulted in a 90% yield from HA-WI. The structural features of the sulfated- HA (S-HA) were investigated by FT-IR and ¹H-NMR spectroscopy. The FT-IR and NMR patterns revealed the similarity in both the FTIR spectrum as well as NMR spectrum of both reference standard and purified HA from S. dysgalactiae. The anti-inflammatory activities of HA and S-HA were examined on LPS-induced RAW 264.7 cells. S-HA was significantly inhibited production of pro-inflammatory mediators such as nitric oxide (NO) and PGE₂ and the gene levels of iNOS and COX-2, which are responsible for the production of NO and PGE₂, respectively. Furthermore, S-HA also suppressed the overproduction of pro-inflammatory cytokine TNF-α (<80 pg/ml) and IL-6 (<100 pg/ml) compared to that of HA-WI. The present study clearly demonstrates that HA-S exhibits anti-inflammatory activities in RAW 264.7 macrophage cells.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.305-311
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• 1997

Sustained release-microspheres and immediate release-pellets were prepared to develop a controlled release multiparticulate system containing both water soluble and insoluble dr ug. Pseudoephedrin.HCl (EPD) and terfenadine (TRF) were used as model drugs, respectively. Sustained release-EPD microspheres were prepared by solvent evaporation method using Eudragit RL or RS as a matrix combined with pH-insensitive film coating. Smaller EPD microspheres were obtained when smaller amount of Eudragit as a matrix material or larger amount of magnesium stearate as a dispersing agent was used. However the obtained microspheres did not show syfficient sustained release characteristics. About 97% of EPD was released after 1 hr irrespective of matrix material used. Subsequent coating of the microspheres with pH-insensitive polymer such as Eudragit RS or ethylcelulose (EC) resulted good sustained in 37.5, 73.3 and 92.0% release of encapsulated EPD in distilled water after 1, 3 abd 7 hr, respectively. It corresponds to mean dissolution time (MDT) of 2.3 hr, which is much larger than that of un-coated EPD microspheres (0.0048 hr). Immediate release TRF pellets were prepared by spherically agglomerated crystallization using Eudragit E as an inert matrix and methylene chloride as a liquid binder. Using Eudragit E alone as a matrix resulted in satisfactory physical properties of the pellets such as sphericity, surface texture and flowability, but led to slower release of TRF from pellets than un-modified TRF powder (MDT of 1.70 vs 1.43 hr in pH 1.2 dissolution medium). Introducing propylene glycol or sodium lauryl sulfate as an emulsifier brought about faster release of TRF from pellets (MDT of 1.14 and 0.95 hr, respectively). In conclusion, microencapsulation by solvent evaporation combined with film coating and spherically agglomerated crystallization were successfully utilized to prepare controlled release multiparticulate system composed of sustained release EPD-microspheres and immediate release TRF pellets.