• Macromolecular Research
• /
• v.12 no.4
• /
• pp.342-351
• /
• 2004

Poly(ethylene glycol) (PEG1K) and sulfonated PEG (PEG1K-SO$_3$) methacrylate (MA) copolymers have been prepared and characterized. The structures of the synthesized copolymers were confirmed by $^1$H and $^{13}$ C NMR spectroscopy and elemental analysis. The bulk characteristics of the copolymers were evaluated by viscosity and thermal analysis. The surface properties of the copolymers were investigated using dynamic contact angle measurements and electron spectroscopy for chemical analysis. The hydrophilicity of the surfaces modified with PEG1KMA or PEG1K-SO$_3$MA increased, possibly as a result of the orientation of the hydrophilic PEG1KMA/PEG1K-SO$_3$MA chains into the water phase. Platelets adhered less to the surfaces of the copolymers than they did to a polyurethane control. In addition, adhesion of platelets to the copolymer surfaces decreased upon increasing the chain density of PEG1KMA and sulfonated PEG1KMA in the copolymers. Both bacterial adhesion and protein adsorption were significantly reduced on the copolymer surfaces and their levels differ depending on the kind of surface or media.

• Macromolecular Research
• /
• v.15 no.2
• /
• pp.160-166
• /
• 2007

Novel multiblock copolymers, based on segmented sulfonated hydrophilic-hydrophobic blocks, were synthesized and investigated for their application as proton exchange membranes. A series of segmented sulfonated poly(arylene ether sulfone)-b-polyimide multiblock copolymers, with various block lengths, were synthesized via the coupling reaction between the terminal amine moieties on the hydrophilic blocks and naphthalene anhydride functionalized hydrophobic blocks. Successful imidization reactions required a mixed solvent system, comprised of NMP and m-cresol, in the presence of catalysts. Proton conductivity measurements revealed that the proton conductivity improved with increasing hydrophilic and hydrophobic block lengths. The morphological structure of the multiblock copolymers was investigated using tapping mode atomic force microscopy (TM-AFM). The AFM images of the copolymers demonstrated well-defined nanophase separated morphologies, with the changes in the block length having a pronounced effect on the phase separated morphologies of the system. The self diffusion coefficient of water, as measured by $^1H$ NMR, provided a better understanding of the transport process. Thus, the block copolymers showed higher values than Nafion, and comparable proton conductivities in liquid water, as well as under partially hydrated conditions at $80^{\circ}C$. The new materials are strong candidates for use in PEM systems.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.10
• /
• pp.1436-1439
• /
• 2010

Many studies have clarified that poly(${\gamma}$-glutamic acid) (PGA) increases the solubility of $Ca^{2+}$, suggesting that PGA enhances calcium absorption in the small intestine. However, there has been no report on the specific interaction between PGA and $Ca^{2+}$ in water. We studied the aqueous solution properties of PGA calcium salt (PGA-Ca complex). The chelating ability and binding strength of PGA for $Ca^{2+}$ were evaluated. The PGA-Ca complex was soluble in water, in contrast to the insolubility of poly(acrylic acid) (PAA) calcium salt, and the chelating ability of PGA for $Ca^{2+}$ was almost the same as that of PAA. The globular conformation of the PGA-Ca complex in water was estimated by SEC and viscosity measurements. The chelation ability of PGA for $Ca^{2+}$ was examined by $^1H$ NMR. The present study showing the characteristics of the PGA-Ca complex will provide useful information about the calcium absorption by PGA in vivo.

• Macromolecular Research
• /
• v.15 no.3
• /
• pp.205-210
• /
• 2007

Collagen is the major structural protein of connective tissues. It can be used as a prosthetic biomaterial applicable to artificial skin, tendon, ligaments, and collagen implants. The objective of this study is to investigate the possibility of realizing wound dressing medical products by the synthesis of composite materials with collagen and a biodegradable polymer, PLLA, via a surface modification process. Type I collagen was obtained from pig skin by a separation process. The structural characteristics of the extracted collagen were confirmed by SDS-polyacrylamide (PAcr) gel electrophoresis (PAGE) and FTIR. Also, PLLA-g-PAcr was synthesized by the radical polymerization of acrylamide initiated by AIBN in the presence of PLLA. The surface of PLLA was modified by the presence of the acrylamide residues. The structural characteristics of the copolymer were analyzed by FTIR, $^1H-NMR$ and contact angle measurements. The water uptake and WVTR of the collagen/PLLA-g-PAcr composite tended to increase with increasing collagen concentration and with decreasing EDC concentration.

• Analytical Science and Technology
• /
• v.36 no.2
• /
• pp.70-79
• /
• 2023

The synthesis of the Mannich base as a ligand (L) N-(morpholino (phenyl) methyl) acetamide is the subject of this study. Elemental analyses, FT-IR spectra, UV-vis, ¹H-NMR, and magnetic measurements were used to confirm the synthesis of the [Ni(L)₂]Cl₂ complex, thermal analysis (TG/DTG), atomic absorption, and scanning, and structurally explained as electron microscopy (SEM), and X-ray powder diffraction (XRD) methods. The melting point of the complex and its molar conductivity were also measured. The suggested geometries of the complexes formed have a tetrahedral structure, according to the data acquired using various techniques. Theoretical approaches to the complex formation have been investigated. For molecular mechanics and semi-empirical calculations, the HYPERCHEM6 program had been used. The effect of the novel Ni(II) complex on the cancer cell Hepa-2 (human hepatocellular ademocarcinoma), that is the human laryngeal cancer, was studied. It has been found that these ligand and complex have potent effects on the cancer cell. The antibacterial activity of the free ligand and its complex was evaluated against two kinds of human pathogenic bacteria. The first category is Gram-positive (Staphylococcus aureas, epiderimids), whereas the second group is Gram-negative (Psedamonas aeruginosa, Escherichia coli) (from the diffusion method). Finally, it was discovered that various chemicals had varied growth-inhibiting effects on bacteria.

• Polymer(Korea)
• /
• v.33 no.5
• /
• pp.469-476
• /
• 2009

In this study, biodegradable superporous hydrogels(SPHs) with fast swelling and superabsorbent properties were prepared using biodegradable crosslinkers and their physicochemical properties were characterized. A biodegradable crosslinker (PLA-PEG-PLA DA) was synthesized by a ring opening polymerization of D,L-lactide (LA) using hydrophilic poly(ethylene glycol) as a macroinitiator, followed by diacrylation of the end groups for the introduction of polymerizable vinyl groups. Various kinds of hydrogels with different chemical compositions were prepared and characterized in terms of swelling ratio, swelling kinetics, and biodegradation properties. The synthetic results were confirmed by $^1H$-NMR, FT-IR and GPC measurements, and the porous structures of the prepared SPHs and their porosities were identified by a scanning electron microscope and mercury porosimetry, respectively. The physicochemical properties of SPHs could be controlled by varying their chemical compositions and their cytotoxicity were found to be very low by MTT assay.

• Polymer(Korea)
• /
• v.37 no.3
• /
• pp.308-315
• /
• 2013

In this study, we performed surface modification of silica nanoparticles with bis[3-(triethoxysilylpropyl)]tetrasulfide (TESPT) silane coupling agent to study the effects of treatment temperature, treatment time, and amount of TESPT used on the silanization degree with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), elemental analysis (EA) and solid state $^{13}C$ and $^{29}Si$ cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance spectroscopy (NMR). We found peak area of isolated silanol groups at $3747cm^{-1}$ decreased, but peak area of $-CH_2$ asymmetric stretching of TESPT at $2938cm^{-1}$ increased with the amount of TESPT from FTIR measurements. We also used universal testing machine (UTM) to study mechanical properties of styrene butadiene rubber (SBR) nanocomposites with 20 phr (parts per hundred of rubber) of pristine and TESPT modified silicas, respectively. The tensile strength and 100% modulus of modified silica/SBR nanocomposite were enhanced from 5.65 to 9.38MPa, from 1.62 to 2.73 MPa, respectively, compared to those of pristine silica/SBR nanocomposite.

• Journal of the Korean Chemical Society
• /
• v.54 no.6
• /
• pp.687-695
• /
• 2010

Complexes of thiocyanato(L)cobaloximes where L is urea, acetamide, semicrabazide and formamide were synthesized and characterized. The reaction of thiocyanato (L) cobaloximes (SCNCo$(DH)_2$(L)) with benzyl (aquo) cobaloxime $PhCH_2Co(DH)_2(OH_2)$ was found to produce a series of thiocyanato bridged dicobaloximes of a general formula of $PhCH_2Co(DH)_2SCNCo(DH_2)(L)$. Evidence for formulation as dicobaloximes containing thiocyanato ligand bridges was obtained from infrared data which show $20-45cm^{-1}$ increase in vCN upon formation of the dicobaloxime from the corresponding terminal thiocyanocobaloxime (SCNCo$(DH)_2$(L)). Further characterization of these two series was done on the basis of ($^1H$,$^{13}C$)NMR, LCMS and elemental analysis. Anti-microbial activity of thiocyanato(L)cobaloximes and thiocyanato bridged dicobaloximes were screened against E. Coli. The DNA-binding behaviors of both monomers and dimers were investigated by spectroscopic methods and viscosity measurements. The results indicated that the dimer complexes bind with calf-thymus DNA in an intercalative mode via the terminal benzyl ring into the base pairs of DNA. It was observed that the monomer complexes did not interact with DNA. Fluorescence spectra for the interaction between thiocyanato bridged dicobaloximes and DNA were also studied.

• Applied Chemistry for Engineering
• /
• v.23 no.5
• /
• pp.433-439
• /
• 2012

In this study, a cationic surfactant BHMAS (N,N-bis-(3'-n-dodecyloxy-2'-hydroxypropyl)-N-methyl-2-hydroxyethylammonium methyl sulfate) having two lauryl and three hydroxyl groups was synthesized by the reaction of n-dodecyl glycidyl ether and 2-aminoethanol followed by the quarternization with dimethyl sulfate. The structure of the product was elucidated by $^{1}H-NMR$ and FT-IR. The CMC (critical micelle concentration) and surface tension of BHMAS at CMC condition were found to be $9.12\;{\times}\;10^{-4}$ mol/L and 28.71 mN/m respectively. Dynamic surface tension measurements using a maximum bubble pressure tensiometer indicated that a relatively long time was required to saturate the interface between air and aqueous surfactant solution. The interfacial tension measured between 1 wt% surfactant solution and n-decane reached an equilibrium value of 0.045 mN/m in 5 min. The adsorption capacity of the synthesized surfactant was observed to be excellent, which suggests that the surfactant can be used as a softening agent during a laundry process.

• Membrane Journal
• /
• v.24 no.4
• /
• pp.285-291
• /
• 2014

The PTMSP[Poly(1-trimethylsilyl-1-propyne)]-NaY zeolite composite membranes were prepared by adding 0~50 wt% NaY zeolite to PTMSP. In order to investigate the characteristics of these membranes, we used the analytical methods such as FT-IR, $^1H$-NMR, GPC, DSC, TGA, and SEM. Gas permeation experiments were carried out at $23{\sim}26^{\circ}C$, $2kgf/cm^2$, and the permselectivity of $H_2$ and $N_2$ gases through the composite membranes was studied as a function of the NaY zeolite contents. According to TGA measurements, when NaY zeolite was inserted within the PTMSP, thermal stability of PTMSP was enhanced. Based on SEM observation, NaY zeolite was dispersed in the PTMSP-NaY zeolite composite membrane with a size of $1.5{\mu}m$. The permeability of $H_2$ and $N_2$ through the PTMSP-NaY zeolite composite membranes increased as NaY zeolite content increased. On the contrary, the selectivity($H_2/N_2$) of the PTMSP-NaY zeolite composite membranes decreased as zeolite content increased.