• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.99-100
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• 2006

Orthogonally protected block copolymers of based on p-hydroxystyrene were prepared with high control via nitroxy mediated radical polymerization using an alkoxyamine as an unimolecular initiator. Thin films of partially protected block copolymer were prepared by spin or dip coating. A well defined nanostructure could be observed as a result of phase separation e.g. cylinders in a matrix oriented perpendicular or parallel to the substrate. The nanostructure of the polymeric films can be defined by the block copolymer composition and it determines surface properties and allows further, selective functionalization, e.g. via click chemistry. The thin films can be designed in a way to allow a patterning based on a thermal or photochemical stimulus.

• Macromolecular Research
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• v.9 no.4
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• pp.185-196
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• 2001

The self-assembly of block copolymers can lead to a variety of ordered structures on a nanometer scale. In this article, the self-assembling behaviors of triblock copolymers in the melt and the selective solvent are described with the results obtained from the computer simulations. With the advances of computing power, computer simulations using molecular dynamics and Monte Carlo techniques make it possible to study very complicated phenomena observed in the self-assembly of triblock copolymer. 13king full advantage of the computer simulation based on well-defined model, the effects of various structural and thermodynamic parameters such as the copolymer composition, the block sequence, the pairwise interaction energies, and temperature on the self-assembly are discussed in some detail. Some simulation results are compared with experimental ones End analyzed by comparing them with the theoretical treatment.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1638-1642
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• 2012

A series of poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) tri and multiblock copolymers with relatively high molecular weights were synthesized through the coupling reaction between the bis(acyl chloride) of carboxylated PLA and mono or dihydroxy PEG. The coupling reaction and the copolymer structures were monitored by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The melting temperature (Tm) of PEG blocks decreased with the presence of PLA sequences attaching to PEG blocks. The CMC values were determined to be 10-145 mg/L depending on the length of PLA and PEG blocks and the structure of the block copolymers.

• Macromolecular Research
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• v.15 no.7
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• pp.656-661
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• 2007

The effects of a neutral solvent of dioctyl phthalate (DOP) on the phase behavior of symmetric polystyrene-block-poly(n-butyl methacrylate) copolymers (PS-b-PnBMA) were assessed herein. Closed-loop phase behavior with a lower disorder-to-order transition (LDOT) and an upper order-to-disorder transition (UODT) was observed for PS-b-PnBMA/DOP solution when the quantity of DOP was carefully controlled. When the molecular weight of PS-b-PnBMA became larger, the LDOT did not appreciably change at smaller quantities of DOP. With larger quantities of DOP, the reduction in the UODT is greater than the increase in the LDOT. This behavior is discussed in accordance with a molecular theory predicated on a compressible random-phase approximation.

• Macromolecular Research
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• v.13 no.5
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• pp.435-440
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• 2005

This study describes a method where the match of two different length scales, i.e., the patterns from self-assembled block copolymer (<50 nm) and electron beam writing (>50 nm), allow the nanometer scale pattern mask. The method is based on using block copolymers containing a poly(methyl methacrylate) (PMMA) block, which is subject to be decomposed under an electron beam, as a pattern resist for electron beam lithography. Electron beam on self assembled block copolymer thin film selectively etches PMMA microdomains, giving rise to a polymeric nano-pattern mask on which subsequent evaporation of chromium produces the arrays of Cr nanoparticles followed by lifting off the mask. Furthermore, electron beam lithography was performed on the micropatterned block copolymer film fabricated by micro-imprinting, leading to a hierarchical self assembled pattern where a broad range of length scales was effectively assembled, ranging from several tens of nanometers, through submicrons, to a few microns.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.80-80
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• 2006

As the size scale of features continue to shrink in devices, the use of self-assembly, i.e. a "bottom up" approach, for device fabrication becomes increasingly important. Yet, simple self-assembly alone will not be sufficient to meet the increasing demands place on the registry of structures, particularly nanostructured materials. Several criteria are key in the rapid advancement and technology transfer for self-assembling systems. Specifically, the assembly processes must be compatible with current $^{\circ}{\infty}top\;down^{\circ}{\pm}$ approaches, where standard photolithographic processes are used for device fabrication. Secondly, simple routes must be available to induce long-range order, in either two or three dimensions, in a rapid, robust and reliable manner. Thirdly, the in-plane orientation and, therefore, ordering of the structures, must be susceptible to a biasing by an external, macroscopic means in at least one, if not two directions, so that individual elements can be accessed in a reliable manner. Block copolymers, specifically block copolymers having a cylindrical microdomain morphology, are one such material that satisfy many, if not all, of the criteria that will be necessary for device fabrication. Here, we discuss several routes by which these versatile materials can be used to produce arrays of nanoscopic elements that have high aspect ratios (ideal for templating and scaffolding), that exhibit long-range order, that give access to multiple length scale structuring, and that are amenable to being biased by macroscopic features placed on a surface.

• Macromolecular Research
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• v.10 no.6
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• pp.311-317
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• 2002

The quantitative analysis of polymer micelles consisting of amphiphilic block copolymers was carried out by small-angle neutron scattering (SANS). The block copolymers, made of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether)(poly(EOVE-b-HOVE)), exhibited a sharp morphological transition from a homogeneous solution to a micelle structure with increasing temperature. This transition is accompanied by a formation of spherical domains of poly(EOVE) with a radius around 200 $\AA$. The variations of the size and its distribution of the domains were investigated as a function of polymer concentration and temperature. The validity of SANS analysis, including the wavelength- and incident-beam-smearing effects of the SANS instrument, was examined with a pre-calibrated polystyrene latex.

• Journal of Pharmaceutical Investigation
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• v.22 no.4
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• pp.323-326
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• 1992

$Poly({\varepsilon}-carbobenzoxy\;L-lysine)/poly(ethylene oxide)/poly({\varepsilon}-carbobenzoxy\;L-lysine)$ (LEL) block copolymers containing $poly({\varepsilon}-carbobenzoxy\;L-lysine)$ (PCLL) as the A component and poly(ethylene oxide) (PEO) as the B component were investigated as drug delivery matrix. PCLL homopolymer and LEL block copolymer microspheres containing anticancer drug, cytarabine, were prepared by a solvent evaporation process and the release patterns of cytarabine from the microspheres were investigated in vitro. The size of PCLL homopolymer and LEL block copolymer microspheres was ranged from $0.2\;{\mu}m$ to $1\;{\mu}m$ in diameter and the shape of the microspheres was almost round. The release pattern of cytarabine from the block copolymer microspheres was dependent on the mole % of PEO of the block copolymers.

• Macromolecular Research
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• v.13 no.2
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• pp.152-155
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• 2005

A dynamic density functional theory is presented for the observation of the phase revolutions of a solution-casting film of di- and tri-block copolymers under solvent evaporation conditions. With the evaporation of the solvent, the inverted phases, the minor part of the component becomes the continuous phase at the higher solvent evaporation rate, as observed in this experiment. Further simulation revealed that these inverted phases are converted into the normal phase and the major part of the component becomes the continuous phase, implying that the inverted phases observed in this experiment are unstable.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.198-198
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• 2006

We have identified sodium benzanilide (Na-BA), sodium diphenyl amine (Na-DPA) and sodium deoxibenzoin (Na-DB) as very efficient initiators for the living anionic polymerization of HIC. It has a slow propagation rate with the additive function of chain end protection, offering in the process a perfect control over MW and MWD. The well-defined amphiphilic coil-rod, coil-rod-coil, and rod-coil-rod block-copolymers of PHIC and P2VP with controlled architecture have been synthesized for the first time with ${\sim}100\;%$ yields. The resulting block copolymers showed lamellar film, donuts, solid and hollow micelles, by simply varying the solvents and the block compositions.