• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1160-1169
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• 1999

In this study, the silane primers were introduced to improve the interface adhesion between copper and epoxy. Especially, the polymer types obtained by solution and emulsifier-free emulsion polymerization of vinyltriethoxysilane and the low molecular weight types of 3-aminopropyltriethoxysilane(3-APTES) and 3-glycidoxypropyltrimethoxysilane(3-GPTMS) were used to improve the adhesion strength between epoxy and copper. Also, the surface of copper was treated by 1,1,1-trichloroethane. According to the results, the interfacial adhesion strength of copper-epoxy increased about 2~5 times with the introduction of silane primer. Also, the optimum treatment time of copper surface was about 10 minutes. Additionally, the adhesion strength as a function of concentration of low molecular weight silane was maximum at about 0.5 vol.% for 3-APTES and about 0.2 vol% for 3-GPTMS.

• Polymer(Korea)
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• v.26 no.3
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• pp.400-409
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• 2002

Polyurethane microcapsules containing functional oil (citronella oil) were successfully prepared by conventional interfacial polymerization of tolulene 2,4-diisocyanate (TDI) and ethylene glycol (EG) and characterized by Fourier transform (FT-IR) spectroscopy, Ultraviolet spectroscopy, particle size analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Tile effects of polymerization variables, such as surfactant concentration and agitation speed, on the particle size and particle size distribution were investigated. FT-IR spectroscopic data showed that citronella oil was successfully encapsulated in the microcapsule. Thermogravimetric analysis data showed that the microcapsule was thermally stable up to $220^{\circ}C$. The controlled release of the citronella oil present in the microcapsule core in a methanol medium was demonstrated by ultraviolet spectroscopy showing that the amount of released citronella oil was increased with increasing time. It was observed that the amount of released citronella oil was increased with increasing stirring speed and emulsifier concentration in the rnicrocapsule preparation step. Polyurethane microcapsules containing citronella oil showed excellent anti-moth property.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.422-426
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• 2005

Visible-light activated polymer nanocomposites (PNC) were designed to be used for dental restoration. Hybrid-filler composed of barium silicate and nano-sized silica was adopted as a filler system. To improve the interfacial be havior of the resin matrix of bisphenol A glycerolate methacrylate/triethyleneglycol dimethacrylate, the surface of filler was hydrophobically treated with a silane coupling agent. Mechanical properties of PNC were investigated by measuring the abrasion resistance, and it was discovered that PNC showed excellent properties with an increase of nanofiller content. However, the polymerization shrinkage was consistently maintained under 3 vol% and the shrinkage continued even after photo-polymerization. In addition, a slight color difference between PNC specimens was observed with increase of nanofiller content.

• Membrane Journal
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• v.33 no.6
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• pp.383-389
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• 2023

A high-performance forward osmosis (FO) membrane was prepared using polyethylene glycol diacrylate (PEGDA) hydrogel as a support layer. Through the UV-induced polymerization and subsequent phase separation of PEGDA, the crosslinked, hydrophilic, and porous PEGDA suppor layer was obtained. To achieve high FO flux and salt selectivity using the fabricated PEGDA support, a selective layer was synthesized via the toluene-assisted interfacial polymerization (TIP), in which toluene is used as an organic solvent. The prepared PEGDA-based FO membrane showed higher FO water flux and lower salt selectivity compared with commercial HTI membranes using 1.0 M NaCl draw solution and DI water feed solution. We propose the strategy to fabricate high-performance FO membranes utilizing supports formed with new hydrophilic materials and fabrication processes.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.443-460
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• 1998

The purpose of this study was to estimate the changes of tensile bond strength according to the difference in lining materials and lining area. Seventy non-carious extracted human molars were used in the present study, and they were randomly assigned into 2 experimental groups according to the difference in lining materials. Each experimental group was subdivided into 3 groups according to the difference in lining area. Circular cavities were prepared on the dentin surface to a diameter of 1.5mm, 2.0mm, 2.5mm and the prepared cavities were filled with Fuji II LC( Glass Ionomer Cement : GIC) or Dycal. Dentin specimens without circular cavity were used as control group. The primer and bonding agent of All-Bond 2 and composite resin (Z-100, 3M Dental Products, U. S. A.) were applied to the exposed dentin surface with or without lining. Tensile bond strengths for the experimental specimens were then measured. To examine the interface between dentin and liner & between liner and composite resin, two specimens from each group were fabricated and observed under the SEM. The results were as follows. 1. Tensile bond strength for the specimens lined with GIC was higher than that for specimens lined with Dycal. However, there was no significant difference between two groups(p>0.05). 2. Tensile bond strength for the specimens lined with GIC in a diameter of 1.5mm(GIC-1.5mm lining group) was statistically higher than that for the GIC-2.0mm lining group and GIC-2.5mm lining group(p<0.05). 3. Tensile bond strength for the specimens lined with Dycal in a diameter of 2.5mm (Dycal-2.5mm lining group)was statistically lower than that for Dycal-1.5mm lining group and Dycal-2.0mm lining group(p<0.05). 4. It was possible to observe the good adhesion of the resin composite to the GIC and the presence of a fissure between GIC and dentin all along the interface. Interfacial gaps of 7.2-$72.2{\mu}m$ between GIC and dentin were observed. The interfacial gap between GIC and dentin at the cavity base was greater. However, the gap was gradually decreased toward the occlusal portion. 5. It was possible to observe the poor adhesion of the resin composite to the Dycal. The detachment of Dycal was occurred all along the composite resin-Dycal interface, and the gaps of 2.0-$30.1{\mu}m$ were formed. In all the specimens, polymerization shrinkage of resin composite caused the detachment of Dycal from the body of Dycal. At a Dycal-dentin interface. it was possible to observe the good adhesion. but poor adhesion with interfacial gap of 2.9-$26.8{\mu}m$ was observed partially.

• Composites Research
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• v.33 no.3
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• pp.125-132
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• 2020

The polymerization shrinkage behavior of dimethacrylate-based composite (Clearfil AP-X, Kuraray) and silorane-based composite (Filtek P90, 3M ESPE) used for dental composite restorations was measured using digital image correlation method. The stress distribution on the surface of specimen was calculated by finite element analysis with equivalent elastic modulus and was compared with the measured shrinkage distribution. Camera images were monitored by a CCD camera during and after the irradiation of light. As a result of the DIC analysis, a non-uniform shrinkage distribution was observed in both composite resins, and the resin core inside the ring specimen had free flowability, leading to in greater shrinkage strain than the resin/ring interfacial region. It was observed that as the distance from the center of the resin increased, the radial average shrinkage strain decreased. The radial average shrinkage strain during light irradiation occurred to be 33% for P90 and 57% for AP-X of the entire strain at the end of the test. The shrinkage behavior of P90 and AP-X was measured to be significantly different from each other during light irradiation. In the resin near the resin/ring interface, it was confirmed that the tensile strain rapidly formed to increase after light irradiation, causing a tensile stressed, interface weak.

• Elastomers and Composites
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• v.39 no.3
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• pp.217-227
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• 2004

A new thermotropic liquid crystalline polymer(TLCP) containing a triad aromatic ester type mesogenic unit and butylene terephthalate unit(BT) in the main chain was synthesized by polycondensation reaction. The TLCP synthesized showed nematic mesophasic behavior and its transition temperature from solid to mesophase was $260^{\circ}C$. The TLCP/PBT blends were prepared by in-situ polymerization in PBT solution and characterized by differential scanning calorimeter(DSC), thermogavimetric analyzer(TGA), scanning electron microscope(SEM), x-ray diffractometer(XRD), and dynamic mechanical thermal analyze, (DMTA). The blends showed well dispersed TLCP phases with domain sizes $0.05{\sim}0.2{\mu}m$ in the PBT matrix. As the increasing TLCP content from 5 to 20 wt%, ${\Delta}Hm$ values of pure PBT in the blend were increased because TLCP acts as a nucleating agent in the PBT matrix. The mechanical properties of the blends depended on the TLCP contents because the TLCP acted effectively as a reinforcing material in the PBT matrix. The blends showed good interfacial adhesion between the TLCP phase and PBT matrix.The blends prepared by in-situ polymerization showed higher mechanical properties and well dispersed TLCP domains than those of the blends prepared by melt blending.

• Steel and Composite Structures
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• v.24 no.1
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• pp.15-22
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• 2017

A green biosynthesis method is described for the preparation of Polyaniline (PANI)-cerium dioxide ($CeO_2$) nanocomposites in different media via in-situ oxidative polymerization procedure. The effect of various media including use of HCl, Lemon Juice, Beverage, White Vinegar, Verjuice and Apple vinegar extracts on the particles size, morphology as well as the conductivity of $PANI-CeO_2$ nanocomposites was investigated. The electron-withdrawing feature of $CeO_2$ increases doping level of PANI and enhances electron delocalization. These cause a significantly blue shift of C = C stretching band of quinoid from $1570cm^{-1}$ to $1585cm^{-1}$. The optical properties of the pure material and polymeric nanocomposites as well as their interfacial interaction in nanocomposite structures analyzed by UV-visible spectroscopy. The DC electrical conductivity (${\sigma}$) of as-prepared HCl doped PANI and a $PANI-CeO_2$ nanocomposite measured by a four-probe method at room temperature was studied.

• Macromolecular Research
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• v.17 no.12
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• pp.1010-1014
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• 2009

Monodispersed microparticles with a poly(D,L-lactide-co-glycolide) (PLGA) core and a poly(ethyl 2-cyanoacrylate) (PE2CA) shell were prepared by Shirasu porous glass (SPG) membrane emulsification to reduce the initial burst release of doxorubicin (DOX). Solution mixtures with different weight ratios of PLGA polymer and E2CA monomer were permeated under pressure through an SPG membrane with $1.9\;{\mu}m$ pore size into a continuous water phase with sodium lauryl sulfate as a surfactant. Core-shell structured microparticles were formed by the mechanism of anionic interfacial polymerization of E2CA and precipitation of both polymers. The average diameter of the resulting microparticles with various PLGA:E2CA ratios ranged from 1.42 to $2.73\;{\mu}m$. The morphology and core-shell structure of the microparticles were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DOX release profiles revealed that the microparticles with an equivalent PLGA:E2CA weight ratio of 1:1 exhibited the optimal condition to reduce the initial burst of DOX. The initial release rate of DOX was dependent on the PLGA:E2CA ratio, and was minimized at a 1:1 ratio.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.361-370
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• 2005

In this review, the field of biosurface organic chemistry is defined and some examples are presented. The aim of biosurface organic chemistry, composed of surface organic chemistry, bioconjugation, and micro- and nanofabrication, is to control the interfaces between biological and non-biological systems at the molecular level. Biosurface organic chemistry has evolved into the stage, where the lateral and vertical control of chemical compositions is achievable with recent developments of nanoscience and nanotechnology. Some new findings in the field are discussed in consideration of their applicability to nanobiotechnology and biomedical sciences.