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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal DOI :
The Polymer Society of Korea
Editor in Chief :
Volume & Issues
Volume 39, Issue 3 - May 2015
Volume 39, Issue 2 - Mar 2015
Volume 39, Issue 1 - Jan 2015
Selecting the target year
Effects of Zeolites on Thermal Stability of Poly(vinyl chloride)
Xu, Jiayou ; Liang, Qinghua ; Xian, Xiumei ; Li, Kaidan ; Liu, Jie ;
Polymer Korea, volume 39, issue 1, 2015, Pages 1~5
DOI : 10.7317/pk.2015.39.1.1
The effects of zeolite on the thermal stability of poly(vinyl chloride) (PVC) were investigated by the static thermal stability test, pyrolysis experiment and ultraviolet spectrum. The results showed that the porous zeolite could absorb hydrogen chloride (HCl), which suppressed the catalysis of HCl on thermal degradation of PVC, thus improved the thermal stability of PVC. The oxidizing acid which was loaded on zeolite had oxidated on the double bond that formed during the dehydrochlorination of PVC. This process could prohibit the growth of the conjugated polyene and improved the color of PVC. Hence, zeolite might be possible to come up with a high performance thermal stabilizer.
Improved Dissolution Behavior of Aceclofenac Loadings with Kollidon VA 64 Using Spray Drying and Rotary Evaporation Process
Yang, Jaewon ; Park, Jin Young ; Lee, Cheon Jung ; Kim, Hye Min ; Lee, Hyun Gu ; Jang, Na Gum ; Ko, Hyun Ah ; Cho, Seon Ah ; Yang, Dae Hyeok ; Khang, Gilson ;
Polymer Korea, volume 39, issue 1, 2015, Pages 6~12
DOI : 10.7317/pk.2015.39.1.6
In order to improve the poor water solubility of aceclofenac, it was loaded into solid Kollidon VA 64 dispersion prepared by spray drying and rotary evaporation methods using different drug and polymer ratios. Morphology and physicochemical behavior of the aceclofenac loaded solid dispersions was analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and differential scanning calorimetry (DSC). Encapsulation efficiency and dissolution behavior in a simulated intestinal juice of aceclofenac in the solid dispersions was measured using HPLC and the latter was compared with that of the active pharmaceutical ingredient (API) and Airtal
. It was demonstrated that two methods could significantly improve the dissolution behavior of aceclofenac.
Methacrylate Polymers Having Pendant Chalcone Moieties: Monomer Reactivity Ratios, Thermal and Optical Properties
Barim, Gamze ; Altun, Ozgul ; Yayla, Mustafa Gokhun ;
Polymer Korea, volume 39, issue 1, 2015, Pages 13~22
DOI : 10.7317/pk.2015.39.1.13
A new methacrylate copolymer that includes chalcone as a side group, poly(4-methacryloyloxyphenyl-4'-methoxystyryl ketone-co-styrene) was synthesized by free radical copolymerization. FTIR and
NMR spectroscopic techniques were used to characterize the homopolymers and copolymers. The copolymerizations were carried out to high conversions. Copolymer compositions were established by
NMR spectra analysis. The monomer reactivity ratios for copolymer system were determined by the linearized Kelen
, and Extended Kelen
methods and a non-linear least squares method. The molecular weights and polydispersity index of copolymers were measured by using the gel permeation chromatography (GPC). The effect of copolymer compositions on their thermal behavior were studied by differential scanning calorimetry and thermogravimetric analysis methods. The optical properties of the resulting copolymer were also investigated.
Preparation and Properties of Shape-Stabilized Phase Change Materials from UHMWPE and Paraffin Wax for Latent Heat Storage
Lee, Hyun-Seok ; Park, Jae-Hoon ; Yim, Jong-Ha ; Seo, Hye-Jin ; Son, Tae-Won ;
Polymer Korea, volume 39, issue 1, 2015, Pages 23~32
DOI : 10.7317/pk.2015.39.1.23
Phase change materials based on ultra high molecular weight of polyethylene (UHMWPE) blended with paraffin wax (mp
) were studied in this paper. In addition, this paper reviews recent studies on the preparation of shape stabilized phase change materials (SSPCM), such as SSPCM from UHMWPE and paraffin wax (mp
), their basic properties and possible applications to latent heat storage. The preparation method was an absorption method. Also, SSPCM composites were prepared by using a hot press at
for 10 min. The analysis for the shape ability of SSPCM to improve heat efficiency was measured by FTIR, SEM, DSC, XRD, and ARES. UHMWPE composites with 30 wt% paraffin wax (mp
) demonstrated less deterioration of physical property and effective thermal property compared with other conditions. As a result, these SSPCMs could be used for the heat storage and release materials for various products.
Release Behavior of Olmesartan Medoxomil from Solid Dispersion Prepared by PVP Addition
Oh, Seung-Chang ; Lee, Cheon Jung ; Lee, Hyun Gu ; Park, Jin Young ; Jeong, Hyun Ki ; Kim, Young-Lae ; Lim, Dong-Kwon ; Lee, Dongwon ; Khang, Gilson ;
Polymer Korea, volume 39, issue 1, 2015, Pages 33~39
DOI : 10.7317/pk.2015.39.1.33
Olmesartan affiliated to biopharmaceutics classification system class 2 is a poorly water soluble drug. For this reason, olmesartan showed a low bioavailability and a lot of difficulties in the process of designing the pharmaceutical formulation. We prepared the solid dispersions of olmesartan. We confirmed the dissolution rate of drug which was prepared by manufacturing. The pharmaceutical formulation of solid dispersions was designed by using PVP as water soluble polymer. We analyzed morphological feature of solid dispersion by employing a scanning electron microscope. Then, the crystalline property of solid dispersion was confirmed through X-ray diffraction and differential scanning calorimeter. Also, the chemical change of solid dispersion was confirmed by the Fourier transform infrared spectroscopy. In vitro dissolution test was used to analyze the dissolution rate of solid dispersion. The prepared solid dissolution olmesartan confirmed the dissolution rate in the pH 1.2. It was compared with olmetec and improved dissolution rate through solid dispersion.
Blood-compatible Bio-inspired Surface of Poly(L-lactide-co-ε-caprolactone) Films Prepared Using Poor Co-solvent Casting
Lim, Jin Ik ; Kim, Soo Hyun ;
Polymer Korea, volume 39, issue 1, 2015, Pages 40~45
DOI : 10.7317/pk.2015.39.1.40
Simple poor-cosolvent casting was used to surface treat biodegradable elastic poly(L-lactide-co-
-caprolactone) (PLCL; 50:50) copolymer films that presented lotus-leaf-like structures. We evaluated whether the lotus-leaflike-structured PLCL (L-PLCL) films could be used as a biomaterial for artificial vascular grafts. The surface morphology, hydrophobicity, and antithrombotic efficiency of the films were examined while immersed in platelet-rich plasma (PRP) using scanning electron microscopy (SEM) and a contact angle meter. The recovery and crystallinity of the films were measured using a tensile-strength testing machine and an X-ray diffractometer, respectively. The solvent containing acetic acid, as a poor co-solvent, and methylene chloride mixed in a 1:2 ratio produced an optimal PLCL film with a water contact angle of approximately
. Furthermore, the surface of the L-PLCL films immersed in PRP showed a lower rate of platelet adhesion (<10%) than that of the surface of an untreated PLCL film immersed in PRP.
Mechanical Properties of Cellulose-filled Epoxy Hybrid Composites Reinforced with Alkali-treated Hemp Fiber
Anand, P. ; Anbumalar, V. ;
Polymer Korea, volume 39, issue 1, 2015, Pages 46~55
DOI : 10.7317/pk.2015.39.1.46
There is a limit for deforestation in order to keep the environmental cycle undisturbed. The heart of the paper is to replace the wood to a maximum extent to obtain a sustainable environment. This research aims at new natural composites in which treated hemp fiber used as reinforcement, synthetic cellulose used as particulate to improve the adhesion between matrix - fiber interface and Epoxy LY556 acted as matrix fabricated by hand layup technique. The density, water absorption, tensile properties, impact strength, hardness, flexural properties and compressive properties have been evaluated under ASTM standards and compare the results with existing materials such as wood, aluminium, etc., The composite hemp fiber reinforced polymer (HFRP) could be exploited as an effective replacement for wood and it would be suitable for automotive applications by comparing results.
Preparation of Isophorone Diisocyanate-loaded Microcapsules and Their Application to Self-healing Protective Coating
Lim, Ye-Ji ; Song, Young-Kyu ; Kim, Dong-Min ; Chung, Chan-Moon ;
Polymer Korea, volume 39, issue 1, 2015, Pages 56~63
DOI : 10.7317/pk.2015.39.1.56
The object of this study is to prepare microcapsules containing a diisocyanate compound, apply them to self-healing protective coating, and evaluate the self-healing capability of the coating by atmospheric moisture. Isophorone diisocyanate (IPDI) polymerized under humid atmosphere, indicating that IPDI can be used as a healing agent. Microencapsulations of IPDI were conducted via interfacial polymerization of a polyurethane prepolymer with diol compounds. The formation of microcapsules was confirmed by Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The mean diameter, size distribution, morphology and shell wall thickness of microcapsules were investigated by optical microscopy and scanning electron microscopy (SEM). The properties of microcapsules were studied by varying agitation rates and diol structure. The self-healing coatings were prepared on test pieces of CRC board. When scratch was generated in the coatings, the core material flew out of the microcapsules and filled the scratch. The self-healing coatings were damaged and healed under atmosphere with 68~89% relative humidity for 48 h, and SEM and impermeability test for the specimens showed that the scratch could be healed by atmospheric moisture.
Physical Properties of Polypropylene Foam Blended with Thermally Expandable Microcapsules
Ha, Jin Uk ; Jeoung, Sun Kyung ; Lee, Pyoung-Chan ; Hwang, Ye Jin ; Nam, Byung Kook ; Han, In-Soo ; Kwak, Sung Bok ; Lee, Jae Yong ;
Polymer Korea, volume 39, issue 1, 2015, Pages 64~70
DOI : 10.7317/pk.2015.39.1.64
Thermally expandable microcapsules (TEMs) can be expanded upon heating since the activation energy of liquid hydrocarbon at the core of the TEMs increased at high temperature. Due to this property, TEMs are widely used in the industry as blowing agents or light-weight fillers. In this article, chemical blowing agent and TEM were used for making polypropylene (PP) foams, and their mechanical properties were compared. Physical properties (tensile strength, impact strength etc.) of PP foams decreased with increasing the amount of blowing agents while weight of specimen decreased. However, PP foam produced with TEMs showed higher impact strength than the one with a chemical blowing agent. In order to figure out the difference of impact strength, the morphology of PP foamed was investigated. Expanding properties of TEM can be controlled by changing core back distance.
Synthesis and Photovoltaic Properties of a Low Band Gap Polymer for Organic Solar Cell
Woo, Yong-Ho ; Lee, Hyo-Sang ; Park, Sungnam ; Choi, E-Joon ; Kim, BongSoo ;
Polymer Korea, volume 39, issue 1, 2015, Pages 71~77
DOI : 10.7317/pk.2015.39.1.71
We synthesized a low band gap alternating copolymer containing electron-rich units (i.e. dithienosiloles and benzodithiophenes) and electron-deficient units (i.e. difluorobenzothiadiazoles) for high performance organic solar cells. The polymer was prepared by the Stille coupling reaction and characterized using
NMR, GPC, TGA, UV-visible absorption spectroscopy, and cyclic voltammetry. Solar cells were fabricated in a structure of ITO/PEDOT:PSS/polymer:
with five different blending ratios of polymer and
(1:1.5, 1:2, 1:3, 1:3.5 and 1:4 by weight ratio). The best efficiency was achieved from the 1:3 ratio of polymer and
in the photoactive layer, and TEM revealed that there is an optimal nanoscale phase separation between polymer and
in the 1:3 ratio blend film.
Suspension Polymerization of Thermally Expandable Microcapsules with Core-Shell Structure Using the SPG Emulsification Technique: Influence of Crosslinking Agents and Stabilizers
Bu, Ji Hyun ; Kim, Yeongseon ; Ha, Jin Uk ; Shim, Sang Eun ;
Polymer Korea, volume 39, issue 1, 2015, Pages 78~87
DOI : 10.7317/pk.2015.39.1.78
With aiming to prepare microcapsules having a particle size of
, thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of
were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.
Functionalized Graphene/Polyimide Nanocomposites under Different Thermal Imidization Temperatures
Ju, Jieun ; Chang, Jin-Hae ;
Polymer Korea, volume 39, issue 1, 2015, Pages 88~98
DOI : 10.7317/pk.2015.39.1.88
4-Amino-N-hexadecylbenzamide-graphene sheets (AHB-GSs), used in the preparation of the polyimide (PI) nanocomposite films, were synthesized by mixing a dispersion of graphite oxide with a solution of the ammonium salt of AHB. The atomic force microscope image of functionalized-GS on mica and a profile plot revealed the average thickness of AHB-GS to be ~3.21 nm. PI films were synthesized by reacting 4,4'-biphthalic anhydride and bis(4-aminophenyl) sulfide. PI nanocomposite films containing various contents of AHB-GS over the range of 0-10 wt% were synthesized using the solution intercalation method. The PI nanocomposite films under different thermal imidization temperatures, 250 and
, were examined. The graphenes, for the most part, were well dispersed in the polymer matrix despite some agglomeration. However, micrometer-scale particles were not detected. The average thickness of the particles was <10 nm, as revealed from the transmission electron microscope images. Only a small amount of AHB-GS was required to improve the gas barrier, and electrical conductivity. In contrast, the glass transition and initial decomposition temperatures of the PI hybrid films continued to decrease with increasing content of AHB-GS up to 10 wt%. In general, the properties of the PI hybrid films heat treated at
were better than those of films heat treated at
Effects of Alkali Treated Nano-kenaf Fiber in Polypropylene Composite upon Mechanical Property Changes
Oh, Jeong Seok ; Lee, Seong-Hoon ; Kim, Kwang-Jea ;
Polymer Korea, volume 39, issue 1, 2015, Pages 99~106
DOI : 10.7317/pk.2015.39.1.99
The surface of nano-kenaf containing cellulose fibers was treated with alkali (NaOH) and their effects on the physical properties of the polypropylene (PP) composite were investigated. The treatment of alkali on the fibers increased the melt flow index (M.I.), elongation%, and impact strength, while it decreased the tensile strength, flexural modulus and heat deflection temperature (HDT) of the compound compared to the untreated one. It seemed the alkali treatment on the nano-kenaf fiber changed the character of the fiber due to removal of impurities and chemicals on the surface and resulted in decreased interfacial adhesion between the nano-fiber surface and the PP matrix and changed the character of the PP.
Effects of Silica-Silane for CIIR Vibration Isolation Compound upon Increased Mechanical Properties
Kim, Sung Min ; Kim, Kwang-Jea ;
Polymer Korea, volume 39, issue 1, 2015, Pages 107~113
DOI : 10.7317/pk.2015.39.1.107
The effects of silica-silane in CIIR vibration isolation compound were investigated regarding mechanical and dynamic properties. Addition of silica-silane in the compound resulted in higher tear resistance strength and elongation at break than the control, which was increased by 13% and 14%, respectively. Other values such as tensile strength and hardness did not show significant changes. Viscoelastic property results supported that the improvement of tear resistance strength and elongation at break resulted from the formation of 3-dimensional network structure between silica and CIIR. The mechanism of the tear resistance strength and elongation at break improvement was discussed.
Effect of Fluorination of Carbon Nanotubes on Physico-chemical and EMI Shielding Properties of Polymer Composites
Lee, Si-Eun ; Kim, Doyoung ; Lee, Man Young ; Lee, Min-Kyung ; Jeong, Euigyung ; Lee, Young-Seak ;
Polymer Korea, volume 39, issue 1, 2015, Pages 114~121
DOI : 10.7317/pk.2015.39.1.114
Mutli-walled carbon nanotubes (MWCNTs) were surface-modified by a hydrofluoric acid solution to remove impurities and improve interfacial bonding and dispersion of nanotubes in an epoxy matrix. The crystallinity on the surface of treated MWCNTs was investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties were characterized by tensile test, and the enhancement of mechanical properties of the modified MWCNTs/epoxy composites was indicated by a 33% increase in tensile strength. The electromagnetic interference shielding effectiveness (EMI-SE) of modified MWCNTs/epoxy composites was improved with an increase in concentration of hydrofluoric solution, and EMI-SE showed the maximum increase with 25% HF. However, mechanical and EMI-SE properties didn't show further increase with over 50% HF concentration because the properties of MWCNTs were influenced by degradation of crystallinity and intrinsic properties of MWCNTs. The mechanical and electrical property enhancements of the polymer composites are attributed to the modification of MWCNTs which improve crystallinity of MWCNTs and dispersion in the epoxy resin.
Antifouling Paint Resin Based on Polyurethane Matrix with Quaternary Ammonium Salt
Kim, Dae-Hee ; Jung, Min-Yeong ; Park, Hyun ; Lee, In-Won ; Chun, Ho-Hwan ; Jo, Nam-Ju ;
Polymer Korea, volume 39, issue 1, 2015, Pages 122~129
DOI : 10.7317/pk.2015.39.1.122
Recently, the development of a new class of anti-fouling paint resin which has excellent anti-fouling performance and no persistence in the marine ecology is necessary. In this study, we first polymerized polyurethanes (PUs) as the other type of matrix which have carboxylic acid groups by using poly(ethylene glycol) (PEG), 4,4'-diphenylmethane diisocyanate (MDI), and 2,2'-bis(hydroxyl methyl)-propionic acid (DMPA). And next, we synthesized final resins having quaternary ammonium salts on pendant acid groups of PUs. After synthesis, the physical self-polishing property of resin by the measurement of reduced thickness in sea water was tested. The mechanical property of antifouling paint resin was good when the molecular weight of PEG was 600 or less. It was confirmed that the adhesion of PU resin was deteriorated when the content of quaternary ammonium salt was incorporated over specific value.
Preparation and Physical Properties of Polypropylene/Cellulose Composites
Jang, Song Yi ; Kim, Dae Su ;
Polymer Korea, volume 39, issue 1, 2015, Pages 130~135
DOI : 10.7317/pk.2015.39.1.130
Cellulose has attracted much attention as potential reinforcements in green composites. In this study, polypropylene (PP)/cellulose composites were prepared by melt-blending followed by compression molding. To improve interfacial bonding between PP and cellulose, maleic anhydride-grafted polypropylene (MAPP) was used. Mechanical properties of the PP/cellulose composites were investigated by UTM and izod impact tester. Thermal properties of the PP/cellulose composites were investigated by TGA and DSC. SEM images for the fracture surfaces of the composites showed that the MAPP was effective in improving PP/cellulose interfacial bonding. Tensile strength and modulus of the composite were maxima when MAPP content, based on cellulose content, was 3 wt%. With increasing cellulose content, the impact strength of the composites decreased but the tensile strength and modulus increased.
Mechanical and Electrical Properties of PVA Nanocomposite Containing Sonochemically Modified MWCNT in Water
Kim, Yeongseon ; Kim, Minjae ; Choi, Jin Kyu ; Shim, Sang Eun ;
Polymer Korea, volume 39, issue 1, 2015, Pages 136~143
DOI : 10.7317/pk.2015.39.1.136
Poly(vinyl alcohol) (PVA) was grafted onto the multiwalled carbon nanotube (MWCNT) using ultrasound in water and modified MWCNT/PVA nanocomposite was prepared. Modified MWCNT had a good affinity with PVA matrix and showed improved dispersion state along with uniform properties. Therefore, the electrical percolation threshold was observed at 0.1 wt% MWCNT. 3.0 wt% modified MWCNT/PVA composite had 50% higher tensile strength, 430% higher elongation at break, and 100% greater modulus. Since the modified MWCNT acted as a nucleation agent, the crystallization temperature increased to
and the crystallinity increased to 11.5% at 5.0 wt% loading concentration.
Regeneration of Intervertebral Disc Using Gellan Sponge Loading PLGA Microspheres
Park, Hyunwoo ; Kim, Hye Yun ; Kwon, Soon Yong ; Khang, Gilson ; Kim, Yong-Sik ;
Polymer Korea, volume 39, issue 1, 2015, Pages 144~150
DOI : 10.7317/pk.2015.39.1.144
Gellan gum as a natural polysaccharide has good heat resistance, acid resistance and enzymes resistance. However, one of the drawbacks of gellan gum might be the lower mechanical strength. In this work, gellan gum scaffolds were mixed with poly(lactic-co-glycolic acid) (PLGA) microsphere in order to improve mechanical properties. The gellan gum scaffolds with various contents of PLGA microsphere were prepared for the regeneration of disc tissues. To evaluate the mechanical strength of hybrid structure of gellan gum and PLGA microsphere, compression strength of the fabricated scaffolds was measured. MTT analysis, SEM observation, histological evaluation and RT-PCR were performed to confirm the effect on the cell growth and extracellular matrix secretion. As a result, it showed the best cell proliferation and extracellular matrix secretion in gellan gum sponge containing 50% PLGA microspheres. In conclusion, this study confirmed that the hybrid structure of gellan gum and PLGA microspheres was found suitable in regeneration of the intervertebral disc.
Novel Porous Materials Prepared by Repeated Directional Crystallization of Solvent
Kim, Hyun Jin ; Lee, Jonghwi ;
Polymer Korea, volume 39, issue 1, 2015, Pages 151~156
DOI : 10.7317/pk.2015.39.1.151
Herein, novel porous structures were fabricated from monomer solutions of dimethylsiloxane and benzene by directional crystallization in twice. First, a honeycomb-like structure was fabricated by
directional crystallization of solvent. By infiltration of the solution and subsequent
directional crystallization, novel structures of different pores in the honeycomb-like structure were fabricated. The porous materials prepared by the repeated directional crystallization have higher indentation modulus and hardness than those of the samples prepared by single directional crystallization. When a higher solution concentration was used in
directional crystallization, the maximum increase (indentation modulus: 2140% increase, indentation hardness: 2330% increase) was obtained. On the other hand, porosity and contact angle were lower in the samples from
directional crystallization than those from
directional crystallization. A large decreases was observed, when a relatively high concentration was used in
directional crystallization (porosity: 21% decrease, contact angle: 36% decrease).
Synthesis and Functionalized Conditions of Quaternized Poly(vinylimidazole-co-trifluoroethylmethacrylate-co-divinylbenzene) Anion Exchange Membrane
Oh, Chang Min ; Hwang, Taek Sung ;
Polymer Korea, volume 39, issue 1, 2015, Pages 157~164
DOI : 10.7317/pk.2015.39.1.157
In this study, we synthesized poly(vinylimidazole-co-trifluoroethylmethacrylate-co-divinylbenzene) (PVTD) copolymer and introduced functional group through quaternization reaction for removing nitrate from drinking water. Also, optimizing conditions (reaction time, reaction temperature and functionalized agents concentration) for introducing the functional group were confirmed. The basic properties such as water uptake, swelling ratio, electrical resistance, ion exchange capacity and anion permselectivity for removing nitrate from drinking water were measured. The optimal values of water uptake, electrical resistance and ion exchange capacity of synthesized anion exchange membrane were 51.2%,
, and 1.04 meq/g, respectively.
Precise Control of Thermoresponsive Properties of Polymers with Hydroxy Groups in the Side Chains
Lee, Hyung-Il ;
Polymer Korea, volume 39, issue 1, 2015, Pages 165~168
DOI : 10.7317/pk.2015.39.1.165
Thermoresponsive polymers were successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry). Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-alkyne. Homopolymers having secondary amine groups, tertiary amines with hydroxyethyl and hydroxypropyl groups were synthesized by adding 2-azido-N-ethyl-ethanamine, 2-[(2-azidoethyl)amino]ethanol, and 2-[(2-azidoethyl)amino]propanol, respectively, to the PHEMA-alkyne backbone using click chemistry. Molecular weight (MW), molecular weight distribution (MWD), and click reaction efficiency were determined by gel permeation chromatography (GPC) and
NMR spectroscopy. The transmission spectra of the 1.0 wt% aqueous solutions of the resulting polymers at 650 nm were measured as a function of temperature. Results showed that the lower critical solution temperature (LCST) could be easily controlled by the length of the hydroxyalkyl groups.
Preparation of Metallocene Catalysts Supported on Aminosilane and Ionic Liquids Functionalized Silica and its Ethylene Polymerization
Yim, Jin-Heong ; Lee, Jeong Suk ; Ko, Young Soo ;
Polymer Korea, volume 39, issue 1, 2015, Pages 169~173
DOI : 10.7317/pk.2015.39.1.169
Metallocene was supported on the silica, which was functionalized with aminosilanes such as aminopropyltrimethoxysilane (1NS) or N-[3-(trimethoxysilyl)propyl]ethylenediamine (2NS), and ionic liquids such as 1-butyl-4-methylpyridinium chloride (Cl), tributylmethylammonium chloride (Amm), benzyldimethyltetradecylammonium chloride (Ben), 1-butyl-1-methylpyrrolidinium chloride (Pyr), and then ethylene polymerizations were performed. The Zr contents of
were lower than those of only aminosilane-treated silicas. However, the polymerization activity of
was higher than that of
. The polymerization activity of
was lower than that of
due to much lower Zr content.
Alignments of Reactive Mesogen Using Rubbed Glass Substrates
Lee, Mongryong ; Bae, Jin Woo ; Kim, Anna ; Yun, Hyeong Seuk ; Song, Kigook ;
Polymer Korea, volume 39, issue 1, 2015, Pages 174~179
DOI : 10.7317/pk.2015.39.1.174
Alignments of photo-reactive mesogen were induced using bare glass substrates without a polymer alignment layer. It was found by using polarized FTIR spectroscopy, polarized microscopy, and birefringence measurement experiments that the reactive mesogen could be aligned along the rubbing direction although the glass substrate without an alignment layer was used. The induction mechanism of the rubbed bare glass is ascribed to that polymers from rubbing clothes are coated on the glass substrate along the rubbing direction and lead the alignment of liquid crystals through intermolecular interactions.
Synthesis and Characterization of Polypropylene-grafted Graphene Oxide via "Grafting-to" Method
Lee, Jong-Hee ; Oh, Chang-Ho ; Lim, Jung-Hyurk ; Kim, Kyung-Min ;
Polymer Korea, volume 39, issue 1, 2015, Pages 180~184
DOI : 10.7317/pk.2015.39.1.180
PP-grafted GO was prepared by the reaction of graphene oxide (GO) containing 2-bromoisobuyryl groups and polypropylene (PP) having hydroxyl groups (PP-OH) via a "grafting-to" method. GO-Br was synthesized by the reaction of GO and 2-bromoisobutyryl bromide under a basic condition. PP-MAH was reacted with ethanolamine to produce PP-OH. The melting temperature of PP-grafted GO was shifted to the higher temperature than that of PP-OH. Also, the thermal stability of PP-grafted GO was increased as compared to PP-OH and GO. These results demonstrated that the grafted coating polymer PP was effective for enhancing the thermal stability of GO. The higher surface roughness of PP-grafted GO was resulted from the chemical attachment of PP on the surface of GO. The characterization of PP-grafted GO was conducted from Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM).
Temperature Dependence of Molecular Arrangements and Curing Reactions of Reactive Mesogen
Lee, Mongryong ; Bae, Jin Woo ; Song, Kigook ;
Polymer Korea, volume 39, issue 1, 2015, Pages 185~190
DOI : 10.7317/pk.2015.39.1.185
Since a transition from liquid crystal to crystal state is slow for the large photo-reactive liquid crystal molecules, it needs a long time for recrystallization of LC242 molecules when lowering the temperature of the liquid crystal. Although liquid crystals usually align along one direction, the directions of individual liquid crystal molecules are little different from one another with increasing temperature, resulting in changes of birefringence of the liquid crystal films. When the photo-reactive liquid crystals are photo-cured, faster curing kinetics and much larger curing degrees are observed for the films cured at the liquid crystal phase.