• Journal of the Korean Graphic Arts Communication Society
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• v.21 no.1
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• pp.21-34
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• 2003

Acid amplifiers derived from a certain class of sulfonates suffer from autocatalytic decomposition in the presence of a strong acid to give corresponding sulfonic acid, which catalyze the composition of the parent sulfonates, leading to the liberation of more of the same sulfonic acids in an exponential manner. In this research we synthesized and evaluated 4-hydroxy-4'-(2-trifluoromethyl)benzenesulfonyloxy isopropylidene dicyclohexane (1), 4,4'-di-(2-trifluoromethyl)benzenesulfonyloxy isopropylidene dicyclohexane (2), 4-hydroxy-4'-(3-trifluoromethyl)benzenesulfonyloxy isopropylidene dicyclohexane (3) and 4,4-di-(3-trifluoromethyl)benzenesulfonyloxy isopropylidene dicyclohexane (4) as novel acid amplifiers with electron withdrawing group. These acid amplifiers (1-4) showed reasonable thermal stability for resist processing temeprature and exhibited higher photosensitivity compared to poly(tert-butyl methacrylate) film without acid amplifiers. Application of acid amplifiers to photofunctional materials, including photoresists, are described as a consequence of the combination of the acid amplifiers with photoacid generator.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.136-139
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• 2004

Olefin/paraffin separation by the facilitated transport membrane using silver salts as carriers has been considered as a promising alternative to the conventional energy intensive distillation process. The basis for the separation is the ability of silver ions to react reversibly with olefin forming silver-olefin complexes.(omitted)

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.437-471
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• 2002

The photosensitivity enhancement of photoresist achieved by the addition of acid amplifiers stems from the autocatalytic decomposition of the acid amplifiers triggered by acidic species generated from a photoacid gen-erator. In this research we synthesized and evaluated 4-hydroxy-4'-p-styrenesulfonyloxy isopropylidene dicyclohex-ane(1), 4,4'-di-p-styrenesulfonyloxy isopropylidene dicyclohexane(2) and 4-p-styrenesulfonyloxy-4'-tosyloxy isopropylidene dicyclohexane(3) as novel acid amplifiers. These acid amplifiers(1-3) showed reasonable thermal stability for resist pro-cessing temperature. As estimated by the sensitivity curve, 1-3 were 2X-12X sensitive than poly(tert-butyl meth-acrylate) film in the presence of a photoacid generator and, therefore, provides practical applicability for photoimaging.

• Polymer(Korea)
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• v.34 no.2
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• pp.154-158
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• 2010

We first synthesized N-phenylcyclotrisiloxazane ($D_3^{NPh}$) through a cyclization of $\alpha$,$\omega$- dichlorohexamethyltrisiloxane with aniline and prepared poly(dimethylsiloxane-co-N-phenylsiloxazane) copolymer (PDMS-NPSOX) by a ring opening copolymerization of them with hexamethylcyclotrisiloxane $D_3$. An acrylate monomer modified with PDMS-NPSOX was synthesized by using chloroethyl methacrylate and copolymerized with methylmethacrylate (MMA) and n-butylacrylate. The composition of the copolymer was chosen to control their glass transition temperature ($T_g$) to 25 $^{\circ}C$. By changing the comonomer from PDMS to PDMS-NPSOX, $T_g$ and adhesive strength of the copolymer were increased from 20 to 25 $^{\circ}C$ and from 1.76 to 2.23 N/cm, respectively.

• Elastomers and Composites
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• v.44 no.3
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• pp.336-342
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• 2009

We measured shear viscosity of polystyrene (PS) and poly(butyl methacrylate) (PBMA) particles, with a capillary rheometer, prepared by suspension polymerization with 1.0 wt% hydrophobic silica as a stabilizer by varying the initiator concentration at $75^{\circ}C$. PS particles with weight average molecular weight of 66,500 g/mol displayed a Newtonian behaior at low shear rates at $190^{\circ}C$. With increasing molecular weight, PS particles showed shear thinning over the entire range of shear rates. For PBMA particles, steady shear measurement was carried out at $170^{\circ}C$. PBMA particles with weight average molecular weight of 156,700 g/mol showed a Newtonian behaior only at low shear rates. PBMA particles also showed shear thinning with an increase in molecular weight and its pattern similar to that of PS. When carbon black was incorporated into PS and PBMA polymers, steady shear measurement was conducted at $170^{\circ}C$. An increase in carbon black concentration in PS and PBMA composite particles exhibited a progressive increase in shear viscosity. The increase in shear viscosity, however, was less pronounced compared to an increase as a function of molecular weight. Preparing PS composites containing carbon black by internal mixing resulted in an increase in shear viscosity. Its increase, however, was found to be less than that shown in PS composite particles. We speculate that this is caused by an enhanced dispersion of carbon black particles with an internal mixer. Yield behavior was not observed in any of the samples we selected in this experiment.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.2
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• pp.95-104
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• 2014

The objective of this study was to evaluate the cytotoxicity of poly (lactic acid) (PLA) nanoparticles. We used a water-soluble, amphiphilic phospholipid polymer, poly (2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB30W), as a stabilizer for the PLA nanoparticles. The PLA nanoparticles and PMB30W-modified PLA (PLA/PMB30W) nanoparticles were prepared by evaporating tetrahydrofuran (THF) from its aqueous solution. Precipitation of the polymers from the aqueous solution produced PLA and PLA/PMB30W nanoparticles with a size distribution of $0.4-0.5{\mu}m$. The partial coverage of PMB30W on the surface of the PLA/PMB30W nanoparticles was confirmed by X-ray photoelectron spectroscopy (XPS) and dynamic light-scattering (DLS). A high-content automated screening assay (240 random fields per group) revealed that the PLA nanoparticles induced apoptosis in a mouse macrophage-like cell line (apoptotic population: 73.9% in 0.8 mg PLA/mL), while the PLA/PMB30W nanoparticles remained relatively non-hazardous in vitro (apoptotic population: 13.8% in 0.8 mg PLA/mL). The reduction of the apoptotic population was attributed to the phosphorylcholine groups in the PMB30W bound to the surface of the nanoparticle. In conclusion, precipitation of PLA in THF aqueous solution enabled the preparation of PLA nanoparticles with similar shapes and size distribution but different surface characteristics. PMB30W was an effective stabilizer and surface modifier, which reduced the cytotoxicity of PLA nanoparticles by enabling their avoidance of the mononuclear phagocyte system.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.660-663
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• 2005

Aiming the development of novel acid amplifiers, 2-hydroxyphenyl-4-methylbenzenesulfonate (1), 3-hydroxyphenyl-4-methylbenzene sulfonate (2), 4-hydroxyphenyl-4-methylbenzenesulfonate (3) were synthesized as the aromatic acid amplifiers with good thermal stability. They were autocatalytically generated p-toluenesulfonic acid in the presence of small amount of acid evolved from a photoacid generator. These aromatic sulfonates showed excellent thermal stability in PtBMA film and were proven to be the first aromatic acid amplifier to act as a photosensitivity enhancer. When these compounds were coupled with a chemically amplified photoresist system, photosensitivity was enhanced up to 3~6 folds.

• Elastomers and Composites
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• v.46 no.1
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• pp.60-69
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• 2011

The various types of PBA/PMMA composite latexes were prepared by $2.1\;{\mu}m$ PBA seeded batch and seeded semi-continuous dispersion polymerization. The morphology of the PBA/PMMA composite latexes by seeded batch process was found to be closely dependant on the weight ratios of methanol/water in polymerization medium and of PBA seed/MMA at the second stage. In general, egg, snowman, confetti, peanut-like nonspherical composite latex particles were formed with increasing amount of water and MMA as a result of the occurrence of the phase separation between PBA seed and PMMA. The morphology of the PBA/PMMA composite latexes by seeded semi-continuous process was controlled by the addition time of MMA, especially, spherical shaped core(PBA)/shell(PMMA) composite latex particles were prepared under the monomer-starved condition at the second stage.

• Journal of Adhesion and Interface
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• v.11 no.3
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• pp.112-119
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• 2010

Poly(methyl methacrylate)/poly(butyl acrylate) PMMA/PBA core-shell composite particles were prepared by the emulsion polymerization of MMA and BA in the presence of different concentration of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the measured conversion and particle size distribution, morphology, average molecular weight distribution, observation of film formation and particle formation, glass transition temperature and physical properties of polymerized core-shell composition particles for using adhesive binder. When the concentration of 0.03 wt% surfactant, the conversions of PMMA and PBA core polymerization are excellent as 95.8% for PMMA core and 92.3% for PBA core. Core-shell composite particles are obtained 90.0% for PMMA/PBA core-shell composite particles and 89.0% for PMMA/PBA core-shell composite particles. It is considered that the core and shell particles are polymerized to be confirmed FT-IR spectra and average molecular weight measured with a GPC, formation of the composite particles is confirmed by the film formation from normal temperature, and composition of inside and outside of the composite particle is confirmed by TEM photograph. The synthesized polymer has two glass transition temperatures, suggesting that the polymer is composed of core polymer and shell polymer unlike general copolymers. It is considered that each core-shell composite particle can be used as a high functionality adhesion binder by the measurement of tensile strength and elongation.