• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.291-293
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• 2022

The preparation of dendritic molecule for photodynamic diagnosis (PDD) or photodynamic therapy (PDT) has been interested on design and synthesis of macromolecule toward a new generation. Herein, the binding site of polyether group is an important role on the construction of macromolecule toward a new generation. Therefore, we will be presented on the preparation of dendritic molecule having the binding site.

• Clean Technology
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• v.12 no.1
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• pp.19-25
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• 2006

In this study, photo-cuarable urethane methacrylate oligomers were synthesized from polyether type polyol (PP series, GP series), isocyanate (2,4-toluene diisocyanate) and hydroxy acrylate (hydroxypropyl methacrylate). We measured basic property including color, viscosity and refractive index of resulting urethane methacrylate. Also we measured tensile strength, elongation, and Young's modulus after photo curing. Photo curing speed was investigated using photo-DSC (TA instrument). In the case of similar polyol structure, as the molecular weight of polyol is increased, tensile strength, Young's modulus, curing rate were decreased, but elongation was increased. As the number of functionality of urethane methacrylate oligomer is increased, tensile strength, Young's modulus, curing rate were increased, but elongation was decreased.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1167-1172
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• 2008

We investigated the glass transition temperatures ($T_g$) of dendrons consisting of conformationally mobile aliphatic polyether dendritic cores plus glassy peripheral polystyrenes (PSs), and linear PSs in the molecular weight range of 1000-8500 g/mol. We compared their $T_g$ behavior depending on their polymeric architecture. The linear PSs show a typical growth of $T_g$ up to 92.5 ${^{\circ}C}$ as the molecular weight increases to 8300 g/mol, while the dendrons display nearly constant $T_g$ values of 58-61 ${^{\circ}C}$, despite the increase of molecular weight with each generation. The striking contrast of Tg behavior would be mainly attributed to the fact that the dendrons keep the ratio of $N_e$/M ($N_e$: number of peripheral chain ends, M: molecular weight) over all the generations. Additionally, for the influence of dendritic spacers on glass transition temperature we prepared dimeric PSs with different linkage groups such as aliphatic ether, ester and amide bonds. We found that the dimer with the ether spacer exhibited the lowest glass transition at 55.4 ${^{\circ}C}$, while the amide linked dimer showed the highest glass transition temperature at 74.2 ${^{\circ}C}$. This indicates that the peripheral PS chains are effectively decoupled by the conformationally flexible ether spacer. The results from this study demonstrated that polymeric architecture and dendritic core structures play a crucial role in the determination of glass transition behavior, providing a strategy for the systematic engineering of polymer chain mobility.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.524-531
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• 2015

To improve the electrochemical and mechanical characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK). The SPEEK organic-inorganic blended composite membranes were prepared by sol-gel casting method. It was loaded with the highly dispersed ceria and cesium-substituted molybdosilicic acid (Cs-MoSiA) and 1,4-diiodobutane which was cross-linking agent contents of $10{\mu}L$. Cs-MoSiA was added to increase proton conductivity. Ceria ($CeO_2$) was used as a free radical scavenger which degrade the membrane in polymer electrolyte membrane water elctrolysis (PEMWE). In conclusion, CL-SPEEK/Cs-MoSiA/Ceria 1% composite membrane showed high proton conductivity 0.2104 S/cm at $25^{\circ}C$ which was better than Nafion 117 membrane.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.539-549
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• 1995

The purpose of this study was to determine the accuracy of 3 implant impression methods by using strain gauge. The models used for this study were partially edentulous mandibular acrylic resin casts Model A, with two abutment analogs in #46,47 extraction site, represented two implant parallel to to the adjacent natural tooth. Model B represent an anterior implant parallel to the adjacene natural tooth and a posterior implant exhibiting a 15-degree lingual inclination. Master framework were fabricated on the master model, and 3 strain gauges were attached to a master framwork to determine the passivity of fit of the framework to sample casts made by the three impression techniques. The master framework was attached to each sample cast with gold screws, which were tightened with the torque driver to ensure a consistent toque application of 10 Ncm. Universal Digital Measuring System UCAM-5BT was used for strain measuring. Impression techniques studid were : 1. unsplinted tapered impression coping, polyvinyl siloxane, stock tray 2. unsplinted squared impression coping, polyether, custom tray 3. squared impression coping splinted with Duralay resin, polyether, custom tray Through analysis on data from this study, the following conclusions were obtained. 1. There were no statistically significant differences between the mean strain recorded from the sample casts made with the tree impression. But only strain values of model A(parallel group) Y-axis was signifcantly differed between Technique 1 and 3(P<0.05). 2. There was no statistically significant difference between model A(parallel group) and model B(15-degree divergent group).

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.561-569
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• 2014

Ceria ($CeO_2$) was used to increase the durability of the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance. The sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) to improve electrochemical characteristics. After sulfonation reaction, the organic-inorganic blended composite membranes were prepared by means of sol-gel casting method with loading the highly dispersed $CeO_2$ and Cs-substituted molybdophosphoric acid (Cs-MoPA) with cross-linking agent (tetrapropyl orthosilicate). Consequently, the composite membrane CL-SPEEK/Silane 4wt%/Cs-MoPA/Ceria(1%) showed the improved characteristics such as 82% of water content, 0.11136 S/cm of proton conductivity at $80^{\circ}C$, 55.50 MPa of tensile strength and 4.37% of breeding out of MoPA.

• Polymer(Korea)
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• v.25 no.5
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• pp.679-690
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• 2001

High resilience PU foams were prepared with polyether type cell opener. The influences of cell opener concentration on the kinetics, rheology, structural stability morphology and open cell content of the obtained foam were investigated and the role of cell opener during cell opening was determined. And mechanical properties as a function of cell opener concentration were studied. It was observed that urea formation reaction was delayed due to high hydrophilicity of cell opener The decrease of viscosity and the increase of tan $\delta$ were confirmed with increasing cell opener concentration so that the resulted foam had low structural stability and high open cell content. The deterioration of matrix and uniform dispersion of hydrogen-bonded urea in matrix with cell opener concentration was revealed by SEM analysis. As a result, elastic properties of the foam matrix were decreased due to high hydrophilicity of cell opener during the preparation of high resilience polyurethane foam and foam with high open cell content resulted. Hardness, tensile strength, tear strength, elongation of foam were decreased with increasing cell opener concentration.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.66-75
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• 2012

Polyurethane foams were synthesized by substituting a portion of petroleum base polyether polyol with castor oil-derived polyol(COP). Contact angle tester and surface tensionmeter were used to examine the compatibility of petroleum base polyether polyol and COP. To investigate the optimum content of COP and surfactant, the content of COP has been changed from 0 wt% to 80 wt%. From the results of polyurethane foams synthesized by surfactant L-580K, DC-5950 and BF-2470, the best mechanical properties was observed when the content of COP was 30wt% and surfactant BF-2470.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.417-421
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• 2005

Novel two synthetic technics using cationic ring-opening copolymerization of tetrahydrofuran (THF) and ethylene oxide (EO), or just polymerized EO on Poly-THF, could lead to random hydroxyl-terminated poly(EO-ran-THF) or tri-block PEG-PTHF-PEC, respectively. These reactions were carried out using $BF_3O(C_2H_5)_2$ as catalyst, 1,4-butanediol or PTHF as diol initiator. Copolymer structures were controlled by monomer feed ratio, or initial PTHF and EO monomer added amount. The molecular weight of polymer was merely dependant on the ratio of [monomer]/[diol], but not on catalyst. Well-defined random and block hydroxyl-terminated copolyether was found to be as the prepolymer for the propellant binder from the experiment to polyurethane with them.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.546-567
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• 2015

Silicone-based surfactants consist of a hydrophobic organosilicone group coupled to one or more hydrophilic polar groups, while the hydrophobic groups of hydrocarbon surfactants are hydrocarbons. Silicone surfactants have been widely used in many industrial fields starting from polyurethane foam to construction materials, cosmetics, paints & inks, agrochemicals, etc., because of their low surface tension, lubricity, spreading, water repellency and thermal and chemical stability. A wide range of silicone surfactant structures are required to provide the functional diversity for reflecting the necessities in the various applications. This review covers the basic properties and the synthetic schemes of polydimethylsiloxane and reactive polysiloxanes as hydrophobic siloxane backbones, the main reaction schemes, such as hydrosilylation reaction, for coupling reactive polysiloxanes to hydrophilic groups, and the synthetic schemes of the main polysiloxane surfactants including polyether-, ionic-, carbohydrate-type surfactants.