• Polymer(Korea)
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• v.37 no.4
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• pp.442-448
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• 2013

In this study, we developed and optimized hydrophilic polymer-based solid dispersion formulations (SDs) using a spray drying method for improving the aqueous solubility of eprosartan, one of poorly soluble drugs that has been broadly used for the treatment of high blood pressure. Hydroxylpropylcellulose (HPC) and poly(vinyl pyrrolidone) (PVP) were used as hydrophilic polymer matrices and poloxamer 407 (P407) added as a polymeric surfactant. Various kinds of solid dispersions with different drug/polymer compositions were prepared and their physico-chemical properties were compared. As the polymer content increased, the drug crystallinity in the SDs significantly decreased and the dissolution properties were enhanced. The PVP based SDs were observed to have relatively reduced crystallinity and an enhanced dissolution rate than HPC-based SDs, due to better miscibility between drug and polymer matrix. For PVP based SDs, the drug crystallinity almost disappeared and the dissolution properties significantly increased by more than 3~7 times.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.584-594
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• 2014

To increase of surface hydrophilicity of polymeric thin films is an important approaching technique for introduction of self-cleaning and/or antifogging properties on the surfaces of those films. In general, hydrophilic surface can be produced by coating non ionic surfactants or by increasing surface energy. Various non-ionic surfactants, such as Tween, Span, and PEG-PPG block copolymers were selected for our experiments, because they are cheap and well soluble in toluene system as well as they contain several reactive hydroxy fuctional groups with coupling agents. Blending conditions influence the PET film surface hydrophilicities. However, the introduction of only these surfactants on the surface of PET films did not show the high durability of hydrophilic properties after washing with water. To improve the durability two types of coupling agents such as epoxide and diisocyanate were adopted. Contact angle of water on hydrophilically coated PET film surface with 6 wt% of isophrone diisocyanate(IPDI) containing coating solution was reached to $8.7^{\circ}$, which was an indirect evidence for very high surface hydrophilicity. A light(500 nm of wavelength) transmittance value of coated PET film was changed only from 87% to 85% with keeping a good transparent property. This film can be usable for self-cleaning film industries.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.684-689
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• 2012

Poly(acrylic acid) (PAA) microspheres is one of the widely-used polymeric materials for the bio-field application and the electric materials. For the synthesis of PAA microspheres, the polymerization technique using surfactants is applied. After the synthesis, the purification and separation processes are required for the removal of surfactant. When general organic solvents were used, many problems, such as huge amount of waste solvent, additional separation processes, and the possibility of residual media, were occurred. Thus, High-pressure Soxhlet extraction using liquid $CO_2$ was developed to solve these problems. In this study, High-pressure Soxhlet extraction of the synthesized PAA microspheres using liquid $CO_2$ was conducted for the removal of Monasil PCA which is used for the dispersion polymerization of acrylic acid in compressed liquid Dimethyl ether (DME). The morphology of the extracted PAA particles was checked by field emission scanning electron microscopy (FE-SEM) and the residual concentration of Monasil PCA was analyzed by inductively coupled plasma - Optical Emission Spectrometer (ICP-OES). For studying the effect of the solvent effect, Soxhlet extraction was conducted using n-hexane, liquid DME, and liquid $CO_2$. In case of n-hexane, some extracted PAA microspheres were produced. However, deformation was also occurred due to the high thermal energy of n-hexane vapor. Liquid DME could not remove Monasil PCA. When using liquid $CO_2$, the extracted PAA microspheres which were free for the residual solvent were produced without deformation. For finding the optimum operating condition, high-pressure Soxhlet extraction was conducted for 8 hours with changing the temperature of reboiler and condenser. When the extractor temperature is $19.6{\pm}0.2^{\circ}C$ and the pressure is $51.5{\pm}0.5$ bar, the best removal efficiency was obtained.