Effects of the addition of dimer acid alkyl esters on the properties of ethyl cellulose.

In this study, we synthesized dimer acid (DA) esters, having short to long alkyl chains, (DA-Cn) by the Diels-Alder reaction and subsequent esterification reaction of fatty acids that were prepared by the hydrolysis of waste vegetable oil. It was found that the DA-Cn were thermally more stable than common petroleum-based plasticizer DOP. When the DOP, DA, or DA-Cn with short alkyl chains were added to ethyl cellulose (EC), the optical clarity and SEM images of the samples showed their good miscibility with those additives in a micro-scale.

Influence of charge densities of randomly sulfonated polystyrene surfaces on cell attachment and proliferation.

Attachment and proliferation of NIH-3T3 fibroblast cells on random polymer surfaces, polystyrene sulfonated acid (PSSAx) with five different degrees of sulfonation (x = 0%, 5%, 10%, 15% and 33%) and on a tissue culture polystyrene (TCPS) surface were studied. The surface properties, wettability and roughness were measured by water-contact angle and atomic force microscopy measurement. The wettability and surface roughness increased with increasing the content of sulfonic acid groups on the surfaces.

Unipolar bistable switching of organic non-volatile memory devices with poly(styrene-co-styrenesulfonic acid Na).

We demonstrated unipolar organic bistable memory devices with 8 x 8 cross-bar array type structure. The active material for the organic non-volatile memory devices is poly(styrene-co-styrenesulfonic acid Na) (PSSANa). From the electrical measurements of the PSSANa organic memory devices, we observed rewritable unipolar switching behaviors with a stable endurance and narrow cumulative probability.

Effects of the type of solvents on the morphology of styrene-methacrylic acid random copolymers cast onto silicon wafer.

The effects of the type of solvents on the aggregation behavior of poly(styrene-ran-methacrylic acid) (PSMAA) cast onto silicon wafer were studied using a SEM method. It was found that polystyrene prepared from DMF formed non-spherical aggregates but that PSMAA formed mixtures of ellipsoids and spheres. As the acid content increased, the spheres having a distinct boundary started contacting each other, and the average size of spherical particles decreased.

Formation of the colloidal particles of sulfonated polystyrene ionomers neutralized with either Na(I) or Ba(II) in ThF/water (1/99) mixture.

The sizes of colloidal particles in THF/water (1/99 v/v) of the sulfonated polystyrene copolymers containing 2.1, 5.1 and 9.

Small-angle X-ray scattering study on poly(ethyl acrylate-co-itaconate) ionomers neutralized with various cations.

The morphology of poly(ethyl acrylate-co-itaconate) ionomers neutralized partly and fully with Na(I), Li(I) and Zn(II) was studied using a small-angle X-ray scattering (SAXS) technique. It was found that the SAXS peak position for the ionomers shifted to lower angle with increasing degree of neutralization for the ionomers containing 5.8 mol% of ionic repeat units.

Effects of molecular weights of sulfonated polystyrene ionomers on the formation of stable colloidal particles in tetrahydrofuran/water (1/99) mixture.

The effects of the molecular weights (MWs) of sulfonated polystyrene copolymers on the colloidal particle sizes and the size distributions were investigated. It was found that the size of colloidal particle of acid copolymer of relatively low MW, being largest in comparison with higher MW sample, decreased strongly and then remained constant at ca. 11 nm upon dilution.

Preparation and biophysical characterization of pluronic F127-dendrimer conjugate as a delivery agent of antisense oligonucleotides.

A series of pluronic F127 conjugated PAMAM dendrimer generation 5 were prepared to evaluate the potential use of dendrimer-pluronic conjugates as a delivery agent of antisense oligonucleotides. The structural features of the conjugates were identified by FT-IR and 1H-NMR spectra. The prepared dendrimer generation 5-pluronic F127 conjugates showed particle size in the range of 50 to 130 nm with reduced zeta potential.

Application of column-switching HPLC method in evaluating pharmacokinetic parameters of zaltoprofen and its salt.

The objective of this study was to compare the pharmacokinetic parameters of zaltoprofen and those of its sodium salt in rats. Zaltoprofen, a potent non-steroidal anti-inflammatory agent, was virtually insoluble in water, but its sodium salt had excellent water solubility. To investigate the effect of aqueous solubility differences upon their pharmacokinetic parameters, minicapsules containing the drug powders were administrated orally to rats, and blood samples were taken via the common carotid artery.

Effects of the neutralization degree on morphologies in "drying-mediated" samples of sodium neutralized poly(styrene-ran-methacrylic acid) copolymers in THF.

To understand the effect of neutralization degree on surface morphologies of drying-mediated samples, un-neutralized, partially and fully Na-neutralized poly(styrene-ran-methacrylic acid) (PSMAA) prepared from THF solutions were investigated using a scanning electron microscope (SEM). We varied the content of acid groups as well as the degree of neutralization of the PSMAA copolymers. The neutralization degree changed the surface morphologies of the polymers significantly.

Determination of three characteristic regimes of weakly charged polyelectrolytes monolayers.

We have demonstrated that monolayer films of randomly charged polystyrene sulfonated acid (PSSA) can be produced by the Langmuir technique, and observed the micro-domain structures, produced by the phase separation of electrostatically charged moieties and the hydrophobic moieties. Using atomic force microscopy and Langmuir isotherm, we found three specific regimes for the polyelectrolytes with various degrees of sulfonation (4-35%); very low charged PSSA (4-5%) in the hydrophobic regime, moderately charged PSSA (6-16%) which possessed a well-balanced nature between electrostatic and the hydrophobic interactions, and strongly amphiphilic nature of PSSA (6-16%) in the ionomer regime. Finally, we could categorize PSSA 35% in the polyelectrolyte regime, due to the dominance of the electrostatic interactions over the hydrophobic interactions.

Effect of the charge on the morphology of sodium salt form of the randomly sulfonated polystyrene ionomer cast onto silicon wafers.

The morphology of the sodium salt form of randomly copolymerized polystyrene sulfonate (Na-PSS) in water/THF(99/1 v/v) cast onto silicon wafers, was studied by using scanning electron microscope (SEM). The contents of the sulfonate repeat units in Na-PSS were 1.1, 2.

Surface modification for polystyrene colloidal particles with controlled charge densities.

A significant amount of polystyrene sulfonated acid (PSSA) and poly(styrene-ran-acrylic acid) (PSAA) random copolymer can be adsorbed by dispersion of PS particles via a swelling-quenching process. A THF-water mixed solvent was used in the swelling process and a large amount of pure water was used, to give a low concentration of THF% in quenching process. Our results showed that functional PSSA groups were randomly and tightly adsorbed to the PS particles.

Aggregation behavior of Na-neutralized styrene-ran-methacrylic acid copolymers in aqueous solution.

The aggregation behavior of un-neutralized, partly and fully Na-neutralized poly(styrene-ran-methacrylic acid) copolymers in aqueous solution was investigated using a SEM technique. It was observed that the un-neutralized copolymer formed spherical particles on the Si wafer, and the average size of particles was ca. 160 nm.

Self-assembly of mixtures of block copolymers of poly(styrene-b-acrylic acid) with random copolymers of poly(styrene-co-methacrylic acid).

The effects of the addition of random copolymers of poly(styrene-co-methacrylic acid) [P(S-co-MAA)] on the self-assembly of block copolymers of poly(styrene-b-acrylic acid) (PS-b-PAA) are described. The effects of variation of five factors, including the MAA content, the weight fraction and molar mass of the P(S-co-MAA), the initial concentration of the mixture, and the length of the PAA segment in the block copolymer, were investigated. With increasing MAA content, the localization of the random copolymer in the aggregate changed from the core to the interface, which led to a morphological transition from spheres to vesicles.