Il-Hyun Park

Kumoh National Institute of Technology · Department of polymer sciwence and engineering

The critical aggregation concentration (cac) has been investigated by means of laser light scattering method in the tertiary aqueous solution systems of neutral polymer/anionic surfactant, where poly(vinyl pyrrolidone) or poly(ethyl oxazoline) are used as neutral polymers and sodium dodecanoate as an anionic surfactant. According to Nagarajan model...

In the system of polyvinyl 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 concentr...

Dyeing of a poly(vinyl alcohol) (PVA) film with a high degree hydrolysis (>98%) using Direct Black 22, a dichroic organic dye, was investigated under various conditions (dye concentration, salt () concentration, and temperature). This process could correctly be analyzed using the Freundlich isotherm () based on the pore model. The Freundlich expone...

Three reactive dichroic dyes with 3,5-dichloro-2,4,6-triazine moiety were synthesized by reaction between dichroic dyes (such as congo red, direct black 22 or direct black 4) and cyanuric chloride. Poly(vinyl alcohol) (PVA) films were dyed with the obtained three reactive dichroic dyes. After 400% drawing of the PVA films, their optical properties...

The polymer concentration dependence of depletion layer was investigated by means of dynamic light scattering after the very small amount of polystyrene spherical latex particles was added into the matrix solution of poly(vinyl alcohol)(PVA)/dimethyl sulfoxide. At the dilute regime, the magnitude of depletion layer kept constant at the level of of...

In the mixed system of supercritical carbon dioxide/organic solvents, poly(vinyl alcohol)(PVA) film of high degree of hydrolysis could be dyed with a dichroic dye of C. I. direct black 22(DB22) and as a result, high durability was obtained. Especially, as a dye dispersant in a supercritical fluid phase, a mixed solvent system of ethylene glycol: di...

Poly(vinyl alcohol)(PVA) with high degree of hydrolysis of above 98% was dissolved in dimethyl sulfoxide(DMSO), and the shear viscosity was measured up to in the semi-dilute solution regime. Next, as probe particle, polystyrene(PS) latex was introduced into this matrix system and its delayed diffusion due to polymer concentration was investigated b...

In order to understand the structure of the existing aggregate in the nanocomposite, which has been prepared with polyester and trisilanolisobutyl polyhedral oligomeric silsesquioxane (TBPOSS), laser light scattering(LLS) and SEM-EDS were applied to its 1,1,1,3,3,3-hexafluoro-2-propanol solution and original sample, respectively. Although aggregate...

The expansion behavior of polystyrene (PS) chains with various molecular weights has been investigated above Flory temperature by viscometry after dissolving in the three different mixed solvents systems such as benzene/n-heptane, 1,4-dioxane/isopropanol, and 1,4-dioxane/n-heptane. Two different regimes are observed as increasing temperature: one r...

Quarternized poly(4-vinyl pyridine)s have been prepared by the reaction of poly (4-vinyl pyridine)s (Mw=50 kg/mol and 200 kg/mol) and alkylating agents varying the carbon numbers of the alkyl groups (m):dimethyl sulfate (m=1) as well as bromoalkane (m= 5, 8, 12, 16, and 22) was used as an alkylating agent. The degree of alkylation was determined by...

In order to investigate the structure and dynamics of atatic poly (vinyl alcohol) (PVA)/water system, laser light scattering experiment has been done in the semi-dilute concentration regime at . The scattering intensity I(q) can be analyzed with the fractal equation of instead of Onstein-Zernike type equation. The fractal dimensionality m was found...

The polymer chain contraction phenomena near the overlap concentration was analyzed using small-angle neutron scattering (SANS). The main polymers chain that were studied include, poly(ethylene-co-20.2 mol % 1-butene) (PEB 10)-ethane and PEB 10-pentane solutions. It was observed that the polymer solution microstructure evolved as the pressure was v...

Poly(ethylene-co-1-butene) diffusion in ethane, propane, butane, and pentane indicates that ethane solutions are remarkably different. For propane, butane, and pentane the dynamic second virial coefficient, kD, is negative near the phase boundary, increases rapidly to positive values within 100 to 200 bar of the respective phase boundary, and appro...

By means of laser light scattering, poly(vinylidene fluoride) (PVDF) chains were found to form complex aggregates of very narrow size distribution even at dilute concentrations of good solvents such as propylene carbonate (PC) and γ-butyrolactone (BL). Almost the same radii of gyration for aggregates in both solvents were obtained as RG 220 ± 10 nm...

We have extensively characterized the fluorescence behavior of unsaturated polyester (UP) resin in the absence and presence of a 1,3-bis-(1-pyrenyl)propane (BPP) fluorescent probe at various dynamic and isothermal cure histories by means of a steady-state fluorescence technique using a front-face illumination equipment. In addition, we explored the...

Modified poly(4-vinylpyridine) was obtained by partial quarternization of nitrogen atoms in pyridine rings of poly(4-vinylpyridine) with methyl group. By means of laser light scattering and fluorescence, it was found that this modified polymer chains were aggregated in the aqueous solution and its structure was core-shell type. The hydrophobic part...

The interaction between poly(diallyldimethylammonium chloride) (PDADMAC) of positive charge per repeating unit and anionic surfactant, sodium dodecyl sulfate (SDS) has been investigated by light scattering, turbidimetry and fluorescence. Chain behavior of PDADMAC in 0.3 M NaCl aqueous solution seems like neutral polymer chain in good solvent. By ad...

Various chain sizes of 3-arm star polystyrenes (PS, MW2.80 × 105, 2.49 × 106 g/mol) in t-decalin solution were measured at the temperature range of 20-70°C by means of viscometry and laser light scattering. In order to show universality in the expansion factor of 3-arm star polymer, it was expected that (N/RG,Br,o2)3/2 τ/τC would be used as an univ...

A series of dilute and semi-dilute poly(ethylene-co-1-butene)/n-alkane and dimethyl ether (DME) solutions have been investigated with high pressure small angle neutron scattering and dynamic light scattering. The n-alkane solvents considered in these investigations were ethane, propane, butane and pentane. The solutions have been examined at 110-15...

The impact of fluorination on polymer solubility in supercritical CO 2 was discussed by comparing the conditions needed to dissolve poly(methylpropenoxyalkyl siloxane) with a dodecylalkyl chain and two poly (methylpropenoxyperfluoroalkyl siloxanes). All the polymers were synthesized and the structure and molecular weight were presented. The molecul...

The cloud-point behavior of fluorinated polyisoprenes (FPI) and fluorinated polybutadienes (FPBD) in supercritical fluid (SCF) CO2 are reported at temperatures from 60 to 170 °C and pressures from 1000 to 3000 bar. These fluorinated polymers were prepared by the addition of difluorocarbene (CF2) to the parent polydienes yielding a gem-difluorocyclo...

Supercritical fluid (SCF) solvent-polymer solution behavior is measured for poly(ethylene-co-1-butene) (PEB10) in pentane, ethane, and dimethyl ether. Small angle neutron scattering (SANS) is used to probe the solution microstructure as the phase boundary is approached. Initial analysis of the SANS data suggested that Rg of PEB10 does not change si...

A study was carried out to measure the expansion factor of the intrinsic viscosity in the polybutadiene/n-propyl acetate (PBD/PA) system. All characteristic information such as Flory temperature, the critical solution temperature, and the scaling constant of the unperturbed chain dimension was sufficiently obtained.

Expansion behavior of poly(methyl methacrylate) (PMMA) chains of high molecular weights dissolved in n-butyl chloride (BC) was investigated near the theta temperature (θ=41.8 °C) by means of viscometry and laser light scattering. The expansion factor a, the universal ratio of the radius of gyration RG to the effective hydrodynamic radius RH, and Kr...

The extent of transesterification reaction, intrinsic viscosity, weight-average molecular weight and hydrodynamic radius of poly(ethylene 2,6-naphthalate) (PEN)/poly(ethylene terephthalate) (PET) (50/50, w/w) blend were measured as a function of reaction time at 280°C. In PEN/PET blend, the reactions between end groups as well as the transesterific...

Inherent viscosities were measured for poly(ethylene oxide) (PEO) in tetrahydrofuran/water (THF/WT). The measured temperature range covered the range from 35 °C close to the lower critical solution temperature Tc of THF/WT system. It was found that near the critical temperature, the inherent viscosities contract down to about one-third of the value...

By condensation of 1,4-, 1,5-, 1,6-, 2,3-, 2,6-, and 2,7-naphthalenediol (ND) isomers with a isophthaloyl chloride six aromatic polyesters were prepared, and after removal of low molecular weight materials by extraction with acetone their properties were investigated. Effects of the isomerism of the naphthylene units on the properties of the polyes...

The coil-to-globule transition of the radius of gyration of polystyrene (PS) samples (M(w): 3.84 X 10(6)-8.42 x 10(6) g/mol) in methylcyclohexane (MCH) solvent has been measured by static light scattering below the theta-temperature (theta = 69.3-degrees-C). In order to analyze our coil-to-globule data as well as already-reported data of polystyren...

The hydrodynamic radius of a polymer coil can be compared to the root-mean-square radius of gyration in terms of a dimensionless parameter. Although there exist some reports that this parameter does not change with coil swelling, the majority of data and recent theoretical efforts indicate that it varies with solvent quality. This paper presents th...

A holographic relaxation spectrometer is described which incorporates high‐frequency phase modulation of the probe or reference beams by means of an electro‐optic modulator. Heterodyne detection at the modulation frequency or two times the modulation frequency provides signals that are proportional to the electric field amplitude of the diffracted...

Probe diffusion in polyacrylamide (PA) gels was investigated with holographic relaxation methods. The probes were a benzospiropyran (SP) dye and bovine serum albumin labeled with p-(isothiocyanato)azobenzene (BSA-ABITC). It was found that the reduced translational diffusion coefficients D/Do of probes in this gel system are well represented by the...

A new high‐temperature capillary viscometer for measuring the viscosity of dilute polymer solutions has been designed, constructed, and extensively tested. The viscometer has combined several valuable capabilities: high‐temperature operation (potentially to 280 °C and tested up to 250 °C), high precision (∼10^-³ s with a temper...

The growth and decay of radiation pressure induced (concentration) gratings (RPIGs) have been monitored by diffraction of a probe beam. In all cases the growth of diffracted intensity in the presence of radiation pressure followed a curve of the form I=I0 [1−exp(Γt/ΤD )]2 where Γ is a constant and ΤD is the characteristic time for diffusion. When t...

We investigated the coil-to-globule transition of several narrow molecular weight distribution polystyrene samples with MW ranging from 2.0 × 106 to 8.6 × 106 g/mol in methyl acetate (solvent) both below the upper θ temperature (θU = 43°C) and above the lower θ temperature (θL = 114°C) using laser light scattering. The collapsed states based upon t...

We report the results of a recent light-scattering investigation on several different high molecular weight (Mw ranging from 4 × 106 to 20 × 106 g/mol) polystyrenes in cyclohexane from θ-temperature to the collapsed state. The temperature (T) dependence of the radius of gyration (Rg) and that of the hydrodynamic radius (Rh) can be represented by ma...

By using a closed-circuit filtration system, we have succeeded in clarifying poly(ethylene terephthalate) (PET) dissolved in hexafluoroisopropanol (HFIP). Such static properties as the radius of gyration Rg, the weight-average molecular weight Mw, and the second virial coefficient A2 and such dynamic properties as the translational diffusion coeffi...

Thesis (Ph. D.)--State University of New York at Stony Brook, 1986. Includes bibliographical references (leaves 135-139).