• Journal of the Korean Chemical Society
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• v.52 no.6
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• pp.727-733
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• 2008

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.489-492
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• 2002

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.1063-1066
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• 2011

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.28-33
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• 1999

Introducing boric acid to the polyviny alcohol(PVA) solutions has a profound effect on the rheological properties through crosslinking between hydroxyl groups of PVA. This study investigates the effect of boric acid on the rheological properties of polyvinyl alcohol(PVA)/dimethyl sulfoxide(DMSO)/water systems in the absence of cations. The viscosity of PVA/ DMSO/water systems containing 1 wt.% boric acid was decreased with increasing water content. PVA/DMSO systems containing 1 wt.% boric acid exhibited rheological properties similar to elastic gels by forming crosslinked structures. On the other hand, PVA/water systems containing 1 wt.% boric acid exhibited rheological properties typical of viscous materials. In-corporation of boric acid into PVA/DMSO system caused a notable change in the viscosity of the system, whereas boric acid had little effect on the viscosity of PVA/water system. PVA/DMSO/boric acid system gave the greatest storage modulus among the PVA solution systems. Increasing water level in the mixed solvent of DMSO and water diminished the storage modulus of the systems.

• Polymer(Korea)
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• v.39 no.3
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• pp.370-381
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• 2015

In the system of poly(vinyl alcohol) (PVA)/dimethyl sulfoxide, the refractive index of polymer was very well matched to that of solvent and thus its scattered intensity could be minimized. After adding small amount of polystyrene latex particle (nominal diameter 200 nm), diffusion behavior of only probe particle was investigated against the concentration of polymer matrix by means of dynamic light scattering. The polymer concentration dependence of its reduced diffusion coefficient was able to be analysed with the stretched exponential function of the reduced concentration $C[{\eta}]$. In very dilute concentration regime, the depletion layer kept constant but at the early semi-dilute regime of $1{\leq}C[{\eta}]{\leq}2.5$, the concentration-dependent exponent of depletion layer ${\delta}$ was appeared to be -0.8 which was very close to theoretical one of -0.85. However it was also observed at the higher concentration that its layer thickness decreased more abruptly than theoretical expectation and this phenomenon was ascribed to Oosawa type attractive interaction between adjacent latex particles.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.190-196
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• 1998

A new sampling and size exclusion chromatography (SEC) method for the analysis of underivatized cellulose are established. In this method, cellulose materials are first dissolved in N-methylmorpholine N-oxide (NMMO) and diluted by adding dimethyl sulfoxide (DMSO) to make the sample solutions of about 0.1% in 50/50 NMMO/DMSO (w/w). Sample solutions are analyzed using a glucose-treated divinylbenzene (DVB) SEC column and DMSO containing 0.05M LiBr and 2.5 blank as the eluant. The flow rate was constant at 1 mL/min and the whole SEC system including the column was heated at $80^{\circ}C$ to reduce the viscosity of DMSO. Addition of 0.05 M LiBr eliminated SEC baseline drifting, and addition of 2.5 blank seems to reduce the interaction between the sample and the column packing. SEC molecular weights were determined using a calibration curve constructed from a series of narrow pullulan standards, and they were used to measure the degree of degradation during two different pulp-to-sponge processings.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1625-1629
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• 2011

Kinetic studies of the reactions of O,O-diphenyl Z-S-aryl phosphorothioates with X-benzylamines have been carried out in dimethyl sulfoxide at 55.0 $^{\circ}C$. The Hammett (log $k_2$ vs ${\sigma}_X$) and Bronsted [log $k_2$ vs $pK_a(X)$] plots for substituent X variations in the nucleophiles are biphasic concave downwards with a maximum point at X = H, and the unusual positive ${\rho}_X$ and negative ${\beta}_X$ values are obtained for the strongly basic benzylamines. The sign of the cross-interaction constant (${\rho}_{XZ}$) is negative for both the strongly and weakly basic nucleophiles. Greater magnitude of ${\rho}_{XZ}$ value is observed with the weakly basic nucleophiles (${\rho}_{XZ}$ = -2.35) compared to with the strongly basic nucleophiles (${\rho}_{XZ}$ = -0.03). The deuterium kinetic isotope effects ($k_H/k_D$) involving deuterated benzylamines [$XC_6H_4CH_2ND_2$] are primary normal ($k_H/k_D$ > 1). The proposed mechanism is a concerted $S_N2$ involving a frontside nucleophilic attack with a hydrogen bonded, four-center-type transition state for both the strongly and weakly basic nucleophiles. The unusual positive ${\rho}_X$ and negative ${\beta}_X$ values with the strongly basic benzylamines are rationalized by through-space interaction between the ${\pi}$-clouds of the electron-rich phenyl ring of benzylamine and the phenyl ring of the leaving group thiophenoxide.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.666-671
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• 1999

In this work, sulfonated poly(phenylene sulfide) (SPPS) was prepared by demethylation with aqueous NaOH solution after poly[methyl[4-(phenylthio)phenyl]sulfonium trifluoromethanesulfonate](PPST) was sulfonated with fumic sulfonic acid(10% $SO_{3}-H_{2}SO_{4}$). PPST soluble in organic solvents was synthesiszed by self-condensation polymerization of methyl-(phenylthio)phenyl sulfoxide(MPPSO). SPPS showed IR bands of asymmetric O=S=O stretching at $1200cm^{-1}$ and S-O stretching at $621cm^{-1}$ from $-SO_{3}H$ group. From the result, it could be known that sulfonic acid groups were introduced to poly(phenylene sulfide). when PPST was sulfonated for 12hr at $150^{\circ}C$, 1.48 sulfonic acid groups were introduced per repeat unit. The weight average molecular weight(Mw) of PPST and SPPS determined by high temperature GPC were 118323 and 131204, respectively. The SPPS exhibited adsorption capacity of ammonia gas $9.67mmol\;NH_{3}/g$ and it was much higher than that of active carbon or silica gel.

• Development and Reproduction
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• v.15 no.4
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• pp.301-308
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• 2011

The tolerance evaluation for abalone Haliotis discus hannai embryos was performed using different concentrations of cryoprotective agents (CPAs): dimethyl sulfoxide, ethylene glycol and propylene glycol added to 0.2 M sucrose, respectively. 4-cell, trochophore and veliger were exposed in each CPA with different concentration for 10, 20 and 30 minutes of immersion time. Developmental rates were increased with decreased concentration of every CPA and decreased immersion time, and differed from types of CPA. Developmental rates of veliger in all the CPAs were higher than those of 4-cell and trochophore. The developmental rates and larval activity indices in ethylene glycol were comparatively higher than those in other CPAs and the effective CPA and its concentration for the cryopreservation of the abalone embryos was suggested as 2.0 M ethylene glycol with equilibration time of 30 minutes.

• Polymer(Korea)
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• v.31 no.6
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• pp.532-537
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• 2007

The rheological properties of the solutions of atactic poly(vinyl alcohol)(PVA) in dimethyl sulfoxide (DMSO) were investigated in terms of molecular weight distribution (MWD) of the polymer. The dynamic viscosity (${\eta}#$) and loss modulus (G") for the PVA/DMSO solutions with broader MWD were lower than those with narrower MWD at the similar $M_w$. It could be explained by the fact that the free volume for the solution with broader MWD at the similar $M_w$ was increased. The storage modulus(G#) of 14 wt% PVA/DMSO solutions with broader MWD was higher than that with narrower MWD at a lower frequency than 1.3 rad/sec, but lower than that with narrower MWD at a higher frequency (>1.3 rad/sec). The slopes of modified Cole-Cole plots of the 14 wt% solutions showed that as the MWD was broadened, the phase transition with frequency was more noticeable.