• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.340-340
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• 2006

Applying force-distance curve measurement by atomic force microscopy to a theoretical mechanical model gives us elastic properties of polymer surfaces. Our group focuses on force-mapping method, in which force-distance curve is performed at each lattice point on a sample surface and subsequently a variety of properties derived from analytical results are combined to construct a 2-dimensional image. With this method we succeeded in deriving Young' s modulus distribution map method of rubbery/rubbery polymer blend surfaces with ${\sim}100\;nm$ lateral resolution. We also applied force-mapping method to another theory to divide distribution of hardness from that of adhesion. We will demonstrate recent progress.

• Polymer Science and Technology
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• v.8 no.6
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• pp.738-747
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• 1997

• Journal of Pharmaceutical Investigation
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• v.21 no.2
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• pp.91-95
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• 1991

Polyethylene glycol, polypropylene glycol and block copolymer of ethylene glycol and propylene glycol were crosslinked by triisocyanate to form water swellable, rubbery polymer. The equilibrium swelling of the hydrogels ranged from 3% to 60% according to the hydrophobic-hydrophilic properties of the prepolymers. Model drugs, sodium salicylate and prednisolone were incorporated in the polymer matrices by swelling loading. Physical properties of the drugs affected the drug release mechanisms due to the change in the swelling behaviors of the polymeric devices. Zero order release was observed in the case of relatively hydrophobic polymer matrices.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.520-523
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• 2003

We used three types of reactive diluents with different chemical structures, N-vinyl-pyrrollidone(NVP), ethyl hexyl acrylate(EHA) and hydroxyehtyl methacrylate(HEMA). It was founded that N-vinylpyrrollidone(NVP) and ethyl hexyl acrylate(EHA) based PUA with low molecular weight polypropylene glycol(PPG) at low oligomer content give high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.178-180
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• 2005

• Membrane Journal
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• v.29 no.1
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• pp.1-10
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• 2019

Poly(ether block amide) (PEBA) is one of the commercially important class of block copolymer very much suitable specifically for $CO_2$ separation. Gas separation membrane need to have good mechanical strength as well as high gas permeability. The crystalline polyamide (PA) block provides the mechanical strength while the rubbery polyether (PE) group being $CO_2$-philic facilitate $CO_2$ permeation though the membrane. Composition of thermoplastic and rubbery phase in the polymer are changed to fit into suitable gas separation application. Although PEBA has good permeability, the selectivity of the membrane can be enhanced by incorporating molecular sieve without affection much the gas permeability. Mixed matrix membrane (MMM), a class of composite membrane combine the advantage of polymer matrix with the inorganic fillers. However, there are some disadvantages based on the compatibility of the inorganic fillers and polymeric phase. This review covers both the advantage and limitations of PEBA block copolymer based composite membrane.

• Korean Membrane Journal
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• v.5 no.1
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• pp.36-42
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• 2003

A Prediction of pervaporation performance was studied by solubility parameter calculation approach for the benzene/cyclohexane mixture system using rubbery blend membrane with various solubility parameters. The solubility parameter of the rubbery blend membranes were controlled with different blend ratio of the poly(acrylonitrile-co-butadiene), poly(styrene-co-butadiene) and poly(vinyl chloride). Screening of blend formulations was accomplished by simple swelling tests. When the content of NBR is increased, the swelling of both benzene and cyclohexane are decreased. However, the ratio of benzene swelling to swelling by cyclohexane (the swelling selectivity) increases. The same is true for blends in which the PVC content is increased. Adoption of a solubility parameter calculation provides an a priori methodology for seeking the best blend formulation.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.15-22
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• 2008

Polyolefin block copolymer has been taking a great deal of attention due to their great potential in polymer industry since a new metallocene catalytic method for producing polyolefin block copolymer was developed by Dow Chemicals. However, so far, there was no systematic study of olefin block copolymer. In this review, Linear polyolefin block copolymers, containing semicrystalline poly (ethylene) (E) blocks and a rubbery block as a thermoplastic elastomer, were investigated in the viewpoint of microphase separation mode, microstructure, deformation behavior, and molecular architecture.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.169-180
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• 1995

A topological theory is introduced to extend Tsenoglou's theory to polymer blends having temporary and permanent networks composed of multicomponent polymers which have miscible and flexible chains. The topological theory may estimate the values of free elastic energy, the molecular weight between entanglements, and the equilibrium shear moduli, and it may establish more correctly the topological relations among these physical quantities. Through such introduction of the topological theory, there can be topologically analyzed the mixing law for the rubbery plateau modulus of a fluid polymer blend, and there can be considered the topological relationship to the equilibrium modulus of an interpenetrating polymer network containing trapped entanglements and dangling segments. The theoretically predictive values are compared and show good agreement with the experimental data for several miscible polymer blends.

• Macromolecular Research
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• v.15 no.2
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• pp.109-113
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• 2007

The surface molecular motion of monodisperse polystyrene (PS) films was examined using scanning vis-coelasticity microscopy (SVM) in conjunction with lateral force microscopy (LFM). The dynamic storage modulus, E', and loss tangent, $tan\delta$, at a PS film surface with number-average molecular weights, $M_n$, smaller than 30 k were found to be smaller and larger than those for the bulk sample, even at room temperature, meaning that the PS surface is in a glass-rubber transition or fully rubbery sate at this temperature when the $M_n$ is small. In order to quantitatively elucidate the dynamics of the molecular motion at the PS surface, SVM and LFM measurements were performed at various temperatures. The glass transition temperature, $T_g$, at the surface was found to be markedly lower than the bulk $T_g$, and this discrepancy between the surface and bulk became larger with decreasing $M_n$. Such an intensive activation of the thermal molecular motion at the PS surfaces can be explained in terms of an excess free volume in the vicinity of the film surface induced by the preferential segregation of the chain end groups.