• Elastomers and Composites
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• v.55 no.4
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• pp.263-269
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• 2020

Novel flexible terpolymers with a reactive moiety were synthesized by coordination polymerization with a metallocene catalyst and a cocatalyst system. C2-symmetric rac-Et(Ind)2ZrCl2 and tri-iso-butylaluminum/dimethylanilinium tetrakis (pentafluorophenyl) borate were employed as the catalyst and cocatalyst, respectively. We synthesized reactive terpolymers consisting of ethylene, a high α-olefin content (1-hexene, 1-octene, 1-decene, and 1-dodecene), and divinylbenzene. The structure and composition of the terpolymers were characterized by 1H-nuclear magnetic resonance analysis. The catalytic activity, polymer yield, molecular weight, and molecular weight distribution were measured as functions of the chain length and high content of α-olefins. Furthermore, the thermal properties and crystallinity of the terpolymers were determined by differential scanning calorimetry and wide-angle X-ray scattering.

• Membrane Journal
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• v.14 no.3
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• pp.250-257
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• 2004

PEG(poly(ethylene glycol)) acrylate/PPG(poly(propylene glycol)) acrylate (PEG/PPG) was prepared using UV induced photopolymerization method to investigate gas permeation properties of the membrane. The effect of PPG content on the solubility, diffusivity, and permeability of $CO_2$, $O_2$, and $N_2$ in PEG/PPG membrane is reported at $25^{\circ}C$ and $35^{\circ}C$. PEG/PPG (9:1) membrane exhibits $CO_2$ permeability coefficient of 28.9 barrer and $CO_2$/$N_2$ pure gas selectivity of 57.9 at $25^{\circ}C$. Permeability coefficient of increased with increasing with PPG content in the membrane. PEG/PPG (5:5) membrane shows $CO_2$ permeability coefficient of 78.9 barrer and $CO_2$/$N_2$ pure gas selectivity of 33.2 at $25^{\circ}C$.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.56-62
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• 2013

Poly (ethylene naphthalate) (PEN), which is likely to be widely used in various application due to good barrier properties, is manufactured by condensation polymerization of 2,6-dimethylnaphthalene dicarboxylate (2,6-NDC) or 2,6-naphthalene dicarboxylic acid (2,6-NDA) with ethylene glycol. In this study, an analytical method to determine monomers in food simulants, which might migrate from PEN food contact materials into food, was developed. The HPLC-UV method was validated for 2,6-NDC and 2,6-NDA. The obtained validation parameters were selectivity, sensitivity, linearity, precision and recovery. The simultaneous HPLC method was considered the be most effective analytical method to determine 2,6-NDC and 2,6-NDA in food simulants.

• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.437-442
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• 2016

A new route for PBT (Poly butylene terephthalate) production from recycled PET (Poly ethylene terephthalate) has been explored. The route consists of glycolysis of PET (Poly ethylene terephthalate) wastes using 1,4-butandiol into BHBT oligomers and polycondensation of the oligomers into PBT oligomer. This process uses post-consumer or post-industrial recycled PET and converts it into high-end PBT type engineering thermoplastic via a chemical recycling process. Zink acetate was used as a catalyst for both glycolysis and polycondensation. Two types of reactor for the glycolysis, batch and semi-batch reactor, were investigated and their performances were compared. Semi-batch reactor removes ethylene glycol (EG) and THF (tetrahydrofuran) during the reaction. Amounts of EG and THF generated during the glycolysis reaction were measured and used as criteria for the reactor performance. Performance of semi-batch reactor was shown to be better than that of batch reactor. Optimum reaction condition for the semi-batch reactor was BD/PET ratio of 4, and reaction temperature of $220^{\circ}C$, giving high EG yield (max 91%) and low production of THF. In addition, it was confirmed that the molecular weight of PBT oligomer increases in accordance with the progress of the polycondensation reaction.

• Membrane Journal
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• v.29 no.4
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• pp.223-230
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• 2019

In this paper, we develop a polymeric blend membrane based on $CO_2$-philic poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate)-poly(oxyethylene methacrylate) (PBEM-POEM) comb copolymer, which was synthesized by facile free radical polymerization. The PBEM-POEM (PBE) comb copolymer was blended with a commercial oligomer, low-molecular-weight poly(ethylene glycol) (PEG, $M_w=200gmol^{-1}$) with various ratios to prepare $CO_2/N_2$ separation membranes. From the result of $CO_2/N_2$ separation test of the PBE/PEG blend membranes with the various PEG contents, we could conclude that with increasing PEG content, the $CO_2/N_2$ selectivity significantly increased while the CO2 permeability decreased showing trade-off relationship. However, when comparing the performance of the PBE/PEG (9 : 1) with the PBE/PEG (7 : 3) membrane, the $CO_2$ permeance decreased by only 8.3%, while the $N_2$ permeance decreased by 69.1%. Therefore, the $CO_2/N_2$ selectivity dramatically increased from 33.8 to 100.3. This could be because the POEM chains, which account for 80% of the PBE copolymer, favorably interact with PEG and lead to a more compact chain structure, which was confirmed by FT-IR, XRD and SEM analysis. The PBE/PEG (7 : 3) blend membrane had the most optimal gas separation performance, showing a $CO_2$ permeance of 170.5 GPU and $CO_2/N_2$ selectivity of 100.3.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.263-263
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• 2006

Poly (ethylene glycol)(PEG) - Poly (${\varepsilon}-caprolactone(CL)$) - Poly (D,L lactide(LA) (PCLA-PEG-PCLA) was synthesized by ring-opening polymerization to form temperature sensitive hydrogel triblock copolymer. The triblock copolymer was acrylated by acryloyl chloride. ${\beta}-amino$ ester was used as a pH sensitive moiety, in this study ${\beta}$- amino ester obtained from 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine, it have pKb around 6.6. pH/temperature sensitive penta-block copolymer (PAE-PCL-PEG-PCL-PAE) was synthesized by addition polymerization from acrylated triblock copolymer, 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine. Their physicochemical properties of triblock and penta-block copolymers were characterized by $^1H-NMR$ spectroscopy and gel permeation spectroscopy. Sol-gel phase transition behavior of PAE-PCL-PEG-PCL-PAE block copolymers were investigated by remains stable method. Aqueous media of the penta-block copolymer (at 20 wt%) changed from a sol phase at pH 6.4 and $10^{\circ}C$ to a gel phase at pH 7.4 and $37^{\circ}C$. The sol-gel transition properties of these block copolymers are influenced by the hydrophobic/hydrophilic balance of the copolymers, block length, hydrophobicity, stereo-regularity of the hydrophobic of the block copolymer, and the ionization of the pH function groups in the copolymer depended on the changing of environmental pH, respectively. The degradation and the stabilization at pH 7.4 and $37^{\circ}C$, and the stabilization at pH 6.4 and $10^{\circ}C,\;5^{\circ}C,\;0^{\circ}C$, of the gel were determined. The results of toxicity experiment show that the penta block copolymer can be used for injection drug delivery system. The sol?gel transition of this block copolymer also study by in vitro test ($200{\mu}l$ aqueous solution at 20wt% polymer was injected to mouse). Insulin loading and releasing by in vitro test was investigated, the results showed that insulin can loading easily into polymer matrix and release time is around 14-16days. The PAE-PCL-PEG-PCL-PAE can be used as biomaterial for drug, protein, gene loading and delivery.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• Membrane Journal
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• v.21 no.3
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• pp.222-228
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• 2011

Poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer was synthesized via atom transfer radical polymerization (ATRP) and used as an electrolyte for electrochromic device. Plasticized polymer electrolytes were prepared by the introduction of propylene carbonate (PC)/ethylene carbonate (EC) mixture as a plasticizer. The effect of salt was systematically investigated using lithium tetrafluoroborate ($LiBF_4$), lithium perchlorate ($LiClO_4$), lithium iodide (LiI) and lithium bistrifluoromethanesulfonimide (LiTFSI). Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) measurements showed that the structure and glass transition temperature ($T_g$) of polymer electrolytes were changed due to the coordinative interactions between the ether oxygens of POEM and the lithium salts, as supported by FT-IR spectroscopy. Transmission electron microscopy (TEM) showed that the microphase-separated structure of PVC-g-POEM was not greatly disrupted by the introduction of PC/EC and lithium salt. The plasticized polymer electrolyte was applied to the electrochromic device employing poly(3-hexylthiophene) (P3HT) conducting polymer.

• Membrane Journal
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• v.23 no.2
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• pp.112-118
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• 2013

Polyancrylonitrile nanofiber membrane (PAM) was prepared by using the electrospinning method with a solution of polyacrylonitrile (PAN) in DMF. The pore-diameter of PAMs and the number of PAM's layer were controlled for the microfiltration (MF) application. In addition, in order to improve the water-flux, AN-PEGMA copolymers have been synthesized via free radical polymerization with poly (ethylene glycol) methyl ether methacrylate and azobisisobutylronitrile (AIBN), and then PAN/AN-PEGMA nanofiber membranes (PAM/APM) were prepared by electrospinning with a mixture of PAN (9 wt%) and AN-PEGMA (3 wt%) in DMF (88 wt%). The prepared membranes were investigated with FT-IR and E.D.S. It was confirmed through scanning electron microscope (SEM), porometer, and porosity analysis that the porous membrane with a uniform diameter (400~600 nm) and a uniform pore characteristics (0.5~0.4 ${\mu}m$) was prepared. For the MF application, water-flux measurements were investigated and then the result was shown that the water permeability value of PAM/APMs introduced AN-PEGMA copolymers was relatively higher than that of the PVdF commercial membrane. From these results, PAN nanofiber membranes prepared by electrospinning could be utilized as a MF membrane.

• Polymer(Korea)
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• v.30 no.2
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• pp.146-151
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• 2006

Linear and branched copolymers consisting of poly(ethylene glycol) (PEG) and $Poly({\varepsilon}-caprolactone)$ (PCL) were prepared to compare the characterization of star-shaped copolymers with various molecular architecture. Linear and branched PEG-PCL (1-arm, 2-arm, 4-arm, and 8-arm) copolymers were synthesized by the ring-opening polymerization of ${\varepsilon}-caprolactone$ in the presence of HCl $Et_2O$ as a monomer activator at room temperature. The synthesized copolymers were characterized with $^1H-NMR$, GPC, DSC, and XRD. As a result of the DSC and XRD, each copolymers showed different thermal properties and crystallinity according to the number of ms. The micellar characterization of linear and branched copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AM, and fluorescence techniques. The critical micelle concentration (CMC) and diameters of micelles depended on the number of arms. Most micelles exhibited a spherical shape in AFM. In this study, we characterized star-shaped PEG-PCL copolymers and investigated their molecular architecture effect on the various properties. Furthermore, we confirmed that the micelles termed with linear and branched PEG-PCL copolymers have possibility as a potential hydrophobic drug delivery vehicle.