• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.1027-1031
• /
• 2011

In order to use carbon dioxide, one of the green house gases, terpolymers have been synthesized from propylene oxide, cyclohexene oxide, and carbon dioxide with zinc glutarate as catalyst. The polymers have been investigated with FT-IR, $^1H$-NMR, DSC. The glass transition temperatures of terpolymers are dependendent upon mass ratio of the poly(alkylene carbonate by Fox equation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.6
• /
• pp.521-525
• /
• 2004

Biodegradation of poly(ethylene carbonate) (PEC) and their terpolymers has been investigated in vitro. PEC has been synthesized with ethylene oxide (EO) and carbon dioxide, which is one of the greenhouse gases using Zinc glutarate has been used as catalyst Carbonate terpolymers have been prepared by the use of EO, cyclohexene oxide(CHO), and carbon dioxide. High biodegradability of PEC and terpolymers with EO. has been observed. Very low biodegradation of poly(propylene carbonate) (PPC) and poly(cyclohexene carbonate) (PCHC) has been shown. The weight loss, FT-IR and SEM have been employed to characterize biodegradability.

• Applied Chemistry for Engineering
• /
• v.9 no.2
• /
• pp.273-277
• /
• 1998

The synthesis of hydroxy-terminated poly(propylene carbonate)(HTPPC) was performed by the reaction of propylene carbonate(PC) with alcohol initiator using metal alkoxides, crown ethers and quaternary onium salts as catalysts. The effects of catalyst structure, types and concentration of alcohol, and solvent were investigated. Among the alkoxide catalysts tested, the ones with higher Lewis acidity and with more nucleophilic alkoxide anion showed higher catalytic activity. Mixed catalysts of metal alkoxied and crown ether showed higher conversion of PC than metal alkoxide alone. Quaternary onium salts of bulky cation exhibited higher catalytic activity. High polar solvent showed higher yield of HTPPC and the yield increased with the decrease of [PC]/[Initiator] ratio.

• Membrane Journal
• /
• v.29 no.2
• /
• pp.88-95
• /
• 2019

Hydrocarbons containing carbon double bonds are generally called olefins and it is extensively used in petro-chemical industry as essential base material. Especially, olefins are essential in polymer synthesis and thus the effective separation and purification of olefins from gas mixture are very important and it gives significant positive effect on the future industrial development. In this study, we fabricated polymeric composite membrane based on poly(1-trimethylsilyl-1-propyne) (PTMSP) for propylene/nitrogen separation and enhancement of its separation performance by grafting amphiphilic copolymer. Furthermore, to accelerate facilitated transport for propylene molecules, Ag salt ($AgBF_4$) and ionic liquid ($EMIM-BF_4$) was incorporated to polymer composite membranes. The neat PTMSP membrane exhibited extremely high gas permeance and low gas selectivity due to its high free volume. To address this issue, PTMSP was grafted with poly(oxyethylene glycol methacrylate) (POEM) and poly(ethylene glycol) behenyl ether methacrylate (PEGBEM). Additionally, the additives such as $AgBF_4$ and $EMIM-BF_4$ further increased the propylene permeance, resulting in increment of propylene/nitrogen selectivity.

• Polymer(Korea)
• /
• v.30 no.2
• /
• pp.152-157
• /
• 2006

Anionic or Zwitter-ionic waterbone polyurethanes (WPU) based on mixtures of hydroxy terminated poly-butadiene and poly(propylene glycol) were prepared and their physical properties were characterized. Particle size of WPU increased with increasing the content of HTPB. It was observed that the microphase separation of soft segments and hart segments increased with increasing the content of HTPB in the WPUs. Zwitter-ionic WPU showed stronger hydrogen bonds between molecules than anionic WPU after drying. Polyurethane films obtained after drying of WPUs exhibit besmechanical properties when the HTPB content among polyols for WPUs were 25wt%. It is postulated that such mechanical properties resulted from different microphase separation of soft segments and hard segments of polyurethane films obtainec after drying of WPUs.

• Macromolecular Research
• /
• v.17 no.8
• /
• pp.591-596
• /
• 2009

To trace the plasticizing effects of propylene glycol (PG) on poly(vinyl alcohol) (PVA), the rheological properties of PVA solutions in dimethyl sulfoxide (DMSO) and the physical properties of PVA films were discussed in terms of PG content. Both properties were closely related to the hydrogen bond breaking effects of PG The 6 and 12 wt% PVA solutions containing PG exhibited Bingham behavior, which was more noticeable at lower plasticizer content and higher polymer concentration. The 6 wt% PVA solutions containing more than 30 wt% PG showed a sudden decrease of viscosity over the frequency range of 0.08 and 0.2 rad/s. However, the 12 wt% PYA solutions showed no viscosity reduction even at a PG content up to 40 wt%. The glass transition temperature of the PVA/PG films was almost linearly decreased with increasing PG content but an abrupt reduction was observed at a plasticizer content 30 wt%, suggesting that the hydrogen bond breaking effects of PG on PVA became dominant between 20 and 30 wt%. This effect was further supported by the similar tendency of the tensile properties.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.5
• /
• pp.647-654
• /
• 2002

The synthesis and characterization of third- and fifth-generation poly(propylene imine) dendrimers terminated with imidazole moieties is reported. Functionalization was achieved using simple peptide coupling reagents. These materials were characte rized by MALDI-MS, NMR, and titration. The use of these endgroup-functionalized dendrimers as catalysts for the hydrolysis of 2,4-dinitrophenyl acetate is described. Molecular simulations provide a basis for interpreting the catalytic data.

• Korean Chemical Engineering Research
• /
• v.58 no.1
• /
• pp.36-43
• /
• 2020

A biliant stent was fabricated using a magnesium alloy wire, a biodegradable metal. In order to control the fast decomposition and corrosion of magnesium alloys in vivo, magnesium alloy wires were coated with biodegradable polymers such as polycaprolactone (PCL), poly(propylene carbonate) (PPC), poly (L-lactic acid) (PLLA), and poly (D, L-lactide-co-glycolide) (PLGA). In the case of PPC, which is a surface erosion polymer, there is no crack or peeling compared to other polymers (PCL, PLLA, and PLGA) that exhibit bulk erosion behavior. Also, the effect of biodegradable polymer coating on the axial force, which is the mechanical property of magnesium alloy stents, was investigated. Stents coated with most biodegradable polymers (PCL, PLLA, PLGA) increased axial forces compared to the uncoated stent, reducing the flexibility of the stent. However, the stent coated with PPC showed the axial force similar to uncoated stent, which did not reduce the flexibility. From the above results, PPC is considered to be the most efficient biodegradable polymer.

• Journal of the Korean Chemical Society
• /
• v.46 no.1
• /
• pp.19-25
• /
• 2002

We measured the variations of potentials and current densities for several polymers. The results were carefully examined to identify various factors such as temperature and pH to influence the potential and rate. The Tafel slope for anodic dissolution was determined by the polarization effect under these conditions. The optimum conditions were established for each case. The second anodic current density peak and maximum current density were designated as the relative polarization sensitivity $(I_r/I_f)$. The mass-transfer coefficient value $({\alpha})$ was determined by the Tafel slope for anodic dissolution on the basis of the polarization effect under optimum conditions.

• Macromolecular Research
• /
• v.16 no.5
• /
• pp.473-480
• /
• 2008

In this study we investigated bacterial and cell adhesion to poly(propylene carbonate) (PPC) films, that had been synthesized by the copolymerization of carbon dioxide (a global warming chemical) with propylene oxide. We also assessed the biocompatibility and biodegradability of the films in vivo, and their oxidative degradation in vitro. The bacteria adhered to the smooth, hydrophobic PPC surface after 4 h incubation. Pseudomonas aeruginosa and Enterococcus faecalis had the highest levels of adhesion, Escherichia coli and Staphylococcus aureus had the lowest levels, and Staphylococcus epidermidis was intermediate. In contrast, there was no adhesion of human cells (cell line HEp-2) to the PPC films, due to the hydrophobicity and dimensional instability of the surface. On the other hand, the PPC films exhibited good biocompatibility in the mouse subcutaneous environment. Moreover, contrary to expectation the PPC films degraded in the mouse subcutaneous environment. This is the first experimental confirmation that PPC can undergo surface erosion biodegradation in vivo. The observed biodegradability of PPC may have resulted from enzymatic hydrolysis and oxidative degradation processes. In contrast, the PPC films showed resistance to oxidative degradation in vitro. Overall, PPC revealed high affinity to bioorganisms and also good bio-degradability.