• Bulletin of the Korean Chemical Society
• /
• 제32권10호
• /
• pp.3644-3649
• /
• 2011

Multinuclear solid-state nuclear magnetic resonance (NMR) experiments were performed to investigate the local structure changes of nanoporous silica during hydrothermal treatment and surface modification with 3-aminopropyltriethoxysilane (3-APTES). The nanoporous silica was prepared by sol-gel polymerization using inexpensive sodium silicate as a silica precursor. Using $^1H$ magic angle spinning (MAS) NMR spectra, the hydroxyl groups, which play an important role in surface reactions, were probed. Various silicon sites such as $Q^2$, $Q^3$, $Q^4$, $T^2$, and $T^3$ were identified with $^{29}Si$ cross polarization (CP) MAS NMR spectra and quantified with $^{29}Si$ MAS NMR spectra. The results indicated that about 25% of the silica surface was modified. $^1H$ and $^{29}Si$ NMR data proved that the hydrothermal treatment induced dehydration and dehyroxylation. The $^{13}C$ CP MAS and $^1H$ MAS NMR spectra of 3-APTES attached on the surface of nanoporous silica revealed that the amines of the 3-aminopropyl groups were in the chemical state of ${NH_3}^+$ rather than $NH_2$.

• 한국잠사곤충학회지
• /
• 제41권3호
• /
• pp.185-195
• /
• 1999

This study was carried out to improve the skin care property of the polyester fabric by finishing with sericin. It was known that skin care function, anti-oxidation, anti-tyrosinase activity and anti-elastase activity can be achieved from sericin finish. But, the moisture regain of the finished fabric was measured simply, because the major cause of the discomfort from polyester fabric has been anounced to be wetness. The effects of various treatment conditions on the properties of the finished fabric were measured, and obtained results were as follows: 1. The moisture regain at 40$^{\circ}C$ 90% RH were increased with the sericin uptake increasing. while it was not significant for the effects on the moisture regain depending on the treatment conditions like the degree of polymerization and treatment concentration of the binder. The moisture release of the fabric having sericin uptake 1%, 2% was faster than non treated fabric. The change of the moisture regain of the finished fabric from 40$^{\circ}C$ 90% RH to room temperature was 4∼5 times higher than that of knitted cotton fabric. 2. The frictional static charge was decreased with the degree of polymerization of the binder increasing. While the sericin uptake and treatment concentration of the binder were not significant. 3. The whiteness value of the fabric was slightly decreased by finishing with sericin and binder. In that cases, W values of the finished fabrics were above 90 while that depending on the degree of polymerization of the binder was not significant. 4. The major cause of the yellowness of the finished fabric was proved to be catalyst. The yellowness of the finished fabric with sulfur containing catalyst was lower than that with amine group containing catalyst. 5. The effects of the treatment concentrations of the cross-linking agent, catalyst and drying time on the wash durability were not significant.

• 한국응용과학기술학회지
• /
• 제38권1호
• /
• pp.300-308
• /
• 2021

본 연구에서는 3차원 네트워크 폴리아크릴산나트륨 겔의 가교환경을 변화시켜 기계적 강도 및 팽윤거동을 제어하고 그 물성을 평가하는 연구를 진행하였다. 일반적으로 겔 용액의 가교도가 증가함에 따라 3차원 네트워크 겔의 팽윤비는 감소하고 겔의 기계적 강도는 증가한다. 본 연구에서는 3차원 네트워크 겔 상의 가교개수밀도를 산출하여, 겔화 과정에서 가교환경에 의존하는 중합효율 및 가교효율을 확인하였다. 그 결과, 겔 용액에서 단량체와 가교제의 중량비가 동일하더라도 가교환경이 달라지면 실제 제조된 겔 내부의 가교개수밀도가 3.6배 이상 달라질 수 있음을 확인하였다. 본 연구에서 시도한 가교개수밀도 기반 겔 평가 방법을 활용하면 효과적인 VOCs 흡수제로써 3차원 네트워크 겔을 최적화 할 수 있으리라 기대된다.

• 폴리머
• /
• 제38권6호
• /
• pp.752-759
• /
• 2014

본 연구에서는 미세 전자 소자용 절연박막 및 차세대 플렉시블 디스플레이 기판으로서 사용이 기대되는 폴리이미드(PI)에 개환 복분해 중합(ring-opening metathesis polymerization)이 가능한 환형 말단 캡핑제(end-capping agent)인 cis-1,2,3,6-tetrahydrophthalic anhydride(CDBA)로 사슬 말단에 가교 반응이 된 가교형 폴리이미드를 합성하였다. 말단 캡핑제의 조성비에 따른 가교형 폴리이미드 박막의 잔류응력 거동은 thin film stress analyzer(TFSA)를 이용한 wafer bending mothod로 온도에 따라 연속적인 거동을 in-situ로 측정하였다. 열특성은 시차 주사 열량계(DSC), 열기계 분석기(TMA) 및 열 중량 분석기(TGA)를 이용하여 측정하였고, 광학 특성은 자외선/가시광선 분광광도계(UV-vis)와 색차계(spectrophotometer)를 이용하였으며, 네트워크 구조의 모폴로지(morphology) 변화를 통해 해석하였다. 말단 캡핑제의 조성비가 증가함에 따라 잔류응력은 27.9에서 -1.3 MPa로 초저응력 및 향상된 열 특성을 나타내었으나, 광학 특성은 감소됨을 보였다. 가교형 폴리이미드 박막의 우수한 특성 발현은 고집적도 다층 구조의 안정성 및 신뢰도가 요구되는 분야의 응용성이 확대될 것으로 기대된다.

• Journal of the Optical Society of Korea
• /
• 제18권6호
• /
• pp.753-761
• /
• 2014

We propose a two-step UV irradiation procedure to fabricate polymer-dispersed liquid crystal (PDLC) films by lamination. During the first UV treatment, before lamination, the UV-curable monomers coated on one film substrate are solidified through photo-polymerization as the phase separation between the liquid crystals and the monomers. Introducing an adhesion-enhancement layer on the other plastic substrate and controlling the UV irradiation conditions ensure that UV-induced cross-linkable functional groups remain on the surfaces of the photo-polymerized layers. Thereby, the adhesion stability between the top and bottom films is much improved during a second (post-lamination) UV treatment by further UV-induced cross-linking at the interface. Because the adhesion-enhancement and PDLC layers prepared by the bar-coating process are solidified before lamination, the PDLC droplet distribution and the cell gap between the two plastic substrates remain uniform under the lamination pressure. This ensures that the voltage-controlled light transmittance is uniform across the entire sample.

• Bulletin of the Korean Chemical Society
• /
• 제32권8호
• /
• pp.2584-2592
• /
• 2011

Nickel nanoparticle-poly(N-vinyl-2-pyrrolidone)/$TiO_2-ZrO_2$ composite (Ni-PVP/$TiO_2-ZrO_2$) was prepared by in situ polymerization method. The physical and chemical properties of Ni-PVP/$TiO_2-ZrO_2$ were investigated by XRD, FT-IR, BET, TGA, SEM and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of methanol-water mixture as solvent. The effects of reaction temperature, the amount of catalyst, amount of support, solvent, and amount of metal for the synthesis of Ni-PVP/$TiO_2-ZrO_2$, were investigated as well as recyclability of the heterogeneous composite. The catalyst used for this synthetically useful transformation showed considerable level of reusability besides very good activity.

• 통합자연과학논문집
• /
• 제3권2호
• /
• pp.96-102
• /
• 2010

It is still controversial where the improved stability of n-octadecyltriethoxysilane self-assembled monolayer (OTE SAM) on plasma-pretreated mica surface exactly originates from. To date, it has been well known that the extensive cross-polymerization between silane headgroups is a crucial factor for the outstanding mechanical strength of the monolayer. However, this study directly observed that the stability comes not only from the cross-links but also, far more importantly, from the direct chemical bonds between silane headgroups and mica surface. To observe this phenomenon, n-octadecyltrichlorosilane monolayers were self-assembled on both untreated and plasma treated mica surfaces, and their adhesion properties at various stress conditions and force profiles in pure water were investigated and compared through the use of the surface forces apparatus technique. It revealed that, in pure water, there is a substantial difference of stability between untreated and plasma treated cases and the plasma treated surface is mechanically much more stable. In particular, the protrusion behavior of the monolayer during contact repetition experiment was always observed in the untreated case, but never in the plasma treated case. It directly demonstrates that the extensive chemical bonds indeed exist between silane head-groups and plasma treated mica surface and dramatically improve the mechanical stability of the OTE monolayer-coated mica substrate.

• 통합자연과학논문집
• /
• 제3권2호
• /
• pp.89-95
• /
• 2010

It is still controversial where the improved stability of n-octadecyltriethoxysilane self-assembled monolayer (OTE SAM) on plasma-pretreated mica surface exactly originates from. To date, it has been well known that the extensive cross-polymerization between silane head-groups is a crucial factor for the outstanding mechanical strength of the monolayer. However, this study clearly showed that the stability comes not only from the cross-links but also, far more importantly, from the direct chemical bonds between silane headgroups and mica surface. To examine this phenomenon, n-octadecyltrichlorosilane monolayers were self-assembled on both untreated and plasma treated mica surfaces, and their adhesion properties at various physical conditions (relative humidity, high stress, and contact repetition) were investigated and compared through the use of the surface forces apparatus technique. It revealed that, in highly humid conditions (>90%RH), there is a substantial difference of stability between untreated and plasma treated cases and the plasma treated surface is mechanically much more stable. It obviously proves that the extensive chemical bonds indeed exist between silane head-groups and plasma treated mica surface and dramatically improve the mechanical stability of the OTE monolayer-coated mica substrate.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1996년도 춘계학술대회
• /
• pp.223-225
• /
• 1996

Poly (ethylene glycol) (PEG)macromers terminated with acrylate groups and interpenetrating polymer networks(IPN) composed of poly(hydroxyethyl methacrylate)(PHEMA) or poly(hydroxyethyl methacrylate-co-hydropropyl methacrylate-co-N-vinyl pyrrolidone) [P(HEMA-co-HPMA-co-NVP)] and PEG macromer were synthesized with the aim of obtaining protein adsorption resisatnt soft contact lens. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Crosslinked P(HEMA) or P(HEMA-co-HPMA-co-NVP) chains were interpenetrated into the cross-linked three-dimensional networks of PEG. It was found that albumin adsorption onto the contact lens prepared by P(HWMA)/PEG IPN decreases with a decrease of molecular weight of PEG whereas its adsorption onto the contact lens prepared by P(HEMA-co-HPMA-co-NVP)/PEG IPN decreases with an increase of molecular weight of PEG. Also, it was found that albumin adsorption onto the both contact lens decreases with an increase of concentration of PEG macromer in the IPN preparation. There are also more adequate in the bioinertness and bioadhesion for the contact lens by P(HEMA)/PEG IPN or P(HEMA-co-HPMA-co-NVP)/PEG IPN than that by P(HEMA) or P(HEMA-co-HPMA-co-NVP).

• 반도체디스플레이기술학회지
• /
• 제14권1호
• /
• pp.1-5
• /
• 2015

This paper deals with the residual stresses developed in an epoxy film deposited on Si wafer. First, chemically induced residual stresses due to the volumetric shrinkage in cross-linking resins during polymerization are treated. The curvature measurement method is employed to investigate the residual stresses. Then, thermally induced stresses are investigated along the interface between the epoxy film and Si wafer. The boundary element method is employed to investigate the whole stresses in the film. The singular stress is observed near the interface corner. Such residual stresses are large enough to initiate interface delamination to relieve the residual stresses.