• Macromolecular Research
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• v.13 no.5
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• pp.397-402
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• 2005

To explore the potential of shell crosslinked micelle (SCM) as a drug carrier, the drug release behavior of poly($\varepsilon$-caprolactone)-b-poly(acrylic acid) (PCL-b-PAA) SCMs was investigated. PCL-b-PAA was synthesized by ring opening polymerization of $\varepsilon$-caprolactone and atom transfer radical polymerization of tert-butyl acrylate, followed by selective hydrolysis of tert-butyl ester groups to acrylic acid groups. The resulting amphiphilic polymer was used to prepare SCMs by crosslinking of PAA corona via amidation chemistry. The drug release behavior of the SCMs was studied, using pyrene as a model drug, and was compared with that of non-crosslinked micelles, especially below the critical micelle concentration (CMC). When the shell layers were crosslinked, the drug release behavior of the SCMs was successfully modulated at a controlled rate compared with that of the non-crosslinked micelles, which showed a burst release of drug within a short time.

• Polymer(Korea)
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• v.27 no.1
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• pp.17-25
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• 2003

Using atom transfer radical polymerization (ATRP), polystyrene macroinitiators and polystyrene-b-poly(t-butyl acrylate) (PS-b-P(tBA) block copolymers were synthesized by CuBr/PMDETA catalyst system in solution. After hydrolysis, polystyrene-b-poly(acrylic acid), amphiphilic block copolymers, were formed. Subsequent neutralization of polyacid block led to the block ionomers. The molecular weight of the synthesized PS-b-P(tBA) block copolymers was easily-controlled to 5000-10000 and their distributions were less than 1.2. The chemical structures of the synthesized block copolymers were characterized by $^1$H-NMR and FT-IR. In the DSC thermograms, $T_g$ appeared in the vicinity of 100 $^{\circ}C$ because of higher styrene content. In addition, the phase separation of the block ionomers was observed by TEM.

• Polymer(Korea)
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• v.33 no.6
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• pp.515-519
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• 2009

Biodegradable poly((R)-3-hydroxy butyrate) and poly(ethylene glycol) was conjugated to make amphiphilic di-block copolymer. Folate was conjugated at di-block copolymer to target the cancer cells. Copolymer was ready to form the self-assembled micelle whose size was 125~156 nm in aqueous solution. Griseofulvin as a hydrophobic drug was loaded in nanoparticles. Their loading efficiencies were 35~56%. Hydrophobic drug was continuously released for 24 h. Cell viability test showed that folate attached particles were 10% more efficient than the particles without targeting ligands.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.2
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• pp.165-174
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• 2017

This study reports a synthesis of an amphiphilic linear block copolymer consisting of a hydrophobic poly (lactide) (PLA) block and a hydrophilic hyperbranched polyglycerol (hbPG) block, PLA-b-hbPG. Simple chemical modification of the hbPG block with 4-hydroxycinnamic acid (CA) led to a photo-crosslinkable block copolymer, PLA-b-hbPG-CA. Nanosized micelles of the block copolyemrs were used as drug carriers for sustainable release. The hbPG shell made of a small molecular weight hbPG block showed excellent hydrophilicity, which can minimize in vivo toxicity. The UV-crosslinked PLA-b-hbPG-CA micelles loaded with drugs colud be served as a drug delivery carrier for its biocompatibility and self-assembled structures.

• Membrane Journal
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• v.29 no.3
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• pp.183-189
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• 2019

Amphiphilic PCZ-r-PEG random copolymer assisted solvothermal process is used to prepare mesoporous $TiO_2$ microspheres generated from nanoparticles by self-assembly method. Synthesized PCZ-r-PEG is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and transmission electron microscopy (TEM). The mesoporous $TiO_2$ are prepared by PCZ-r-PEG, glucose, water in tertrahydrofuran solution at $150^{\circ}C$ for 12 h and the $TiO_2$ microspheres are calcined at $550^{\circ}C$ for 30 min to further crystallize and organic residue are removed. Morphology and crystallization phase is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The mesoporous $TiO_2$ crystallized in pure anatase phase with diameter of $300{\pm}20nm$.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1987.11a
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• pp.39-46
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• 1987

액정(liquid crystal)은 고체 결정과 등방성 액체의 사이에서 발견되는 중간형태의 물질상태이다. 액정은 일반 유체와 같이 흐를뿐만 아니라 고체가 갖는 이방성 특징을 동시에 갖는다. 액정의 점도는 일반적으로 10-100 Cp 이며 점도가 낮은 기계류 윤활유에 해당한다. 이방성의 특징은 분자들의 긴 간격의 배열에 기인되며 광학적 birefringence로 쉽게 나타나진다. 액정은 세가지 형태로 나누어진다. Thermotropic 액정은 순수화합물이나 균질한 혼합물에서 관찰되는데 온도의 변화에 따라 상이 벼노하한다. 일반적으로 이 액정은 nematic, cholestric, 그리고 smectic 상으로 구분되며 Fig.2에 나타나 있다. Lyotropic 액정은 비누와 같은 amphiphilic분자들이 물과같은 적당한 용매에 용해할 때 나타난다. 이 액정은 Thermotropic 액정과 달리 농도가 상을 결정하는 주요한 변수이다. Polymer 용액은 액정배열을 가지며 Polymeric 액정이라고 불린다. 지금까지 액정에 관해 알려진 지식은 thermotrpic 액정에 관한 것이며 여기서는 이 액정에 관해서만 기술한다.

• Korea-Australia Rheology Journal
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• v.11 no.4
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• pp.321-328
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• 1999

This paper discusses the rheology of complex interfaces comprised of amphiphilic materials that are susceptible to flow-induced orientation and deformation. The consequence of the coupling of the film micro-structure to flow leads to nonlinear rheology and surface fluid dynamics. Experimental methods designed to determine the mechanical rheological material functions of fluid-fluid interfaces as well as local, molecular and morphological responses are presented. These include a newly developed interfacial stress rheometer, flow ultraviolet dichroism, and Brewster-angle microscopy. These techniques are applied to a number of complex interfaces ranging from low molecular weight amphiphiles to polymer monolayers. Nonlinear flow phenomena ranging from two-dimensional nematic responses to highly elastic surface flows that manifest surface normal stress differences and elongational viscosities are described.

• Macromolecular Research
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• v.16 no.5
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• pp.418-423
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• 2008

Poly[(R)-3-hydroxy butyrate] (PHB) and methoxy poly(ethylene glycol) (mPEG) were conjugated by the transesterification reaction with tin(II)-ethylhexanoate (Sn(Oct)-II) as a catalyst. Hydrophobic PHB and hydrophilic mPEG formed an amphiphilic block copolymer which was formed with the self-assembled polymeric micelle in aqueous solution. In this study, we tried to determine the optimum ratio of hydrophobic/hydrophilic segments for controlled drug delivery. The particle size and shape of the polymeric micelle were measured by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Their size were 61-102 nm with various block ratios. Griseofulvin was loaded in the polymeric micelle as a hydrophobic model drug. The loading efficiency and release profile were measured by high performance liquid chromatography (HPLC). The model drug in our system was constantly released for 48 h.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.479-482
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• 1992

Several poly(alkyl methacrylate-b-t-butyl methacrylate) diblock copolymers were synthesized by group transfer polymerization. The molecular weight of poly(t-butyl methacrylate) segments and the composition of the resulting block copolymers were controlled by the monomer feed ratios and mole ratios of monomer to initiator. The poly(t-butyl methacrylate) block was quantitatively hydrolyzed to poly(methacrylic acid) block by refluxing with a catalytic amount of p-toluenesulfonic acid in dioxane at $100^{\circ}C$ for 12 hrs. The thermogravimetric analysis of poly(alkyl methacrylate-b-t-butyl methacrylate) exhibited the lose of isobutylene and subsequent anhydride formation in the range of $205-300^{\circ}C$.

• Macromolecular Research
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• v.17 no.12
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• pp.963-968
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• 2009

Liquid crystal (LC; E7 and/or ML-0249)-embedded, poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based, polymer electrolytes were prepared for use in dye-sensitized solar cells (DSSCs). The electrolytes contained 1-methyl-3-propylimidazolium iodide (PMII), tetrabutylammonium iodide (TBAI), and iodine ($I_2$), which participate in the $I_3^-/I^-$ redox couple. The incorporation of photochemically stable PVdF-co-HFP in the DSSCs created a stable polymer electrolyte that resisted leakage and volatilization. DSSCs, with liquid crystal(LC)-embedded PVdF-co-HFP-based polymer electrolytes between the amphiphilic ruthenium dye N719 absorbed to the nanocrystalline $TiO_2$ photoanode and the Pt counter electrode, were fabricated. These DSSCs displayed enhanced redox couple reduction and reduced charge recombination in comparison to that fabricated from the conventional PVdF-co-HFP-based polymer electrolyte. The behavior of the polymer electrolyte was improved by the addition of optimized amounts of plasticizers, such as ethylene carbonate (EC) and propylene carbonate (PC). The significantly increased short-circuit current density ($J_{sc}$, $14.60\;mA/cm^2$) and open-circuit voltage ($V_{oc}$, 0.68 V) of these DSSCs led to a high power conversion efficiency (PCE) of 6.42% and a fill factor of 0.65 under a standard light intensity of $100\;mW/cm^2$ irradiation of AM 1.5 sunlight. A DSSC fabricated by using E7-embedded PVdF-co-HFP-based polymer electrolyte exhibited a maximum incident photon-to-current conversion efficiency (IPCE) of 50%.