• 폴리머
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• 제36권1호
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• pp.104-110
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• 2012

LCD 컬러필터에서 안료의 분산은 컬러 강도를 증가시키는 중요한 요소이므로, 안료를 분산시키기 위한 안료 분산제의 첨가는 필수적이라 할 수 있다. 안료 분산제로서의 고분자는 안료와의 친화성을 가지는 anchoring group과 매체와의 혼화성을 가지는 stabilizing group을 포함하고 있다. 원자 이동 라디칼 중합은 잘 규정된 고분자 합성을 가능하게 하는 중합법으로, 이러한 구조를 포함하는 고분자형 안료 분산제를 얻기 위한 적절한 수단이 될 수 있다. Anchor로서 (2-dimethylamino)ethyl methacrylate를, stabilizer로서 oligo(ethylene oxide)methyl ether methacrylate를 각각 선택해 고분자 분산제를 합성하였다. 고분자의 구조 및 조성이 안료 분산에 미치는 영향을 연구하기 위해 다양한 길이의 stabilizing group을 가지는 diblock copolymer를 합성하여 비교하였다.

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.121-125
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• 2014

PURPOSE. The purpose of this study was to investigate the bonding properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS. Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and 7 mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minute (Group 4), and resilient liner immersed in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5 mm/min. Data were evaluated by 1-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (${\alpha}$=0.05). RESULTS. The highest mean value of force was observed in Group 3 specimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063). CONCLUSION. Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture base materials compared to the control group.

• Bulletin of the Korean Chemical Society
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• 제13권5호
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• pp.479-482
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• 1992

Several poly(alkyl methacrylate-b-t-butyl methacrylate) diblock copolymers were synthesized by group transfer polymerization. The molecular weight of poly(t-butyl methacrylate) segments and the composition of the resulting block copolymers were controlled by the monomer feed ratios and mole ratios of monomer to initiator. The poly(t-butyl methacrylate) block was quantitatively hydrolyzed to poly(methacrylic acid) block by refluxing with a catalytic amount of p-toluenesulfonic acid in dioxane at $100^{\circ}C$ for 12 hrs. The thermogravimetric analysis of poly(alkyl methacrylate-b-t-butyl methacrylate) exhibited the lose of isobutylene and subsequent anhydride formation in the range of $205-300^{\circ}C$.

• Macromolecular Research
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• 제12권6호
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• pp.586-592
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• 2004

Poly(glycidyl methacrylate)-grafted polyethylene microbeads (POPM) presenting epoxy groups were prepared by radiation-induced graft polymerization of glycidyl methacrylate on the polyethylene microbead. The obtained POPM was characterized by IR spectroscopic, X-ray photoelectrons spectroscopy (XPS), scanning electron microscope (SEM), and thermal analyses. Furthermore, the abundance of epoxy groups on the POPM was determined by titration and elemental analysis after amination. The epoxy group content was calculated to be in the range 0.29-0.34 mmol/g when using the titration method, but in the range 0.53-0.59 mmol./g when using elemental analysis (EA) after amination. The lipase was immobilized to the epoxy groups of the POPM under various experi­mental conditions, including changes to the pH and the epoxy group content. The activity of the lipase-immobilized POPM was in the range from 160 to 500 unit/mg-min. The activity of the lipase-immobilized POPM increased upon increasing the epoxy group content. The lipase-immobilized POPM was characterized additionally by SEM, elec­tron spectroscopy for chemical analysis (ESCA), and EA.

• Macromolecular Research
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• 제17권4호
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• pp.271-275
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• 2009

This paper describes the out-of-plane order of a liquid crystalline(LC) methacrylate copolymer(3) comprised of a methacrylate(1) with a 4-styrylpyridine moiety as the photo-cyclodimerizable group and a benzoate moiety as the mesogenic group in the side chain, and another methacrylate(2) with a 4-(4-methoxyphenyl)benzoate moiety as the mesogenic group. The composition of 1 and 2 units in 3 was estimated to have a molar ratio of 54.2:45.8 by $^{1}H$ NMR spectroscopy. The X-ray diffraction study revealed that the copolymer forms a partial bilayer smectic structure. The copolymer gave rise to a high out-of-plane order parameter of about 0.74 in a wide LC temperature range of $110{\sim}160^{\circ}C$ after linearly polarized, UV light irradiation and subsequent annealing. Moreover, the external reflection IR analysis indicated that excess UV-light irradiation makes the out-of-plane LC structure of the copolymer appear in a higher and wider temperature range.

• 대한화학회지
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• 제54권6호
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• pp.829-834
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• 2010

• 폴리머
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• 제38권2호
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• pp.257-264
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• 2014

본 연구에서는 나노크기의 실리카 입자를 2차 아미노기를 가지는 dipodal 형태의 실란커플링제인 bis[3-(trimethoxysilyl)propyl]ethylenediamine(BTPED)으로 표면 개질한 후, 실리카에 도입되는 2차 아미노기인 N-H기와 마이클 부가 반응이 가능한 acrylate기를 가지는 3-(acryloyloxy)-2-hydroxypropyl methacrylate(AHM)로 표면 처리를 하여 중합 반응성 methacrylate기를 도입하는 연구를 수행하였다. 1 분자에 2차 아미노기를 2개 가지는 BTPED와 마이클 부가 반응성이 있는 acrylate기와 부가 반응성이 없는 methacrylate기를 각각 1개씩 가지는 AHM을 사용하여 BTPED와 AHM의 투입량 및 개질 반응 시간의 변화가 실리카 표면의 methacrylate기 도입에 미치는 영향을 Fourier transform infrared spectroscopy(FTIR), elemental analysis(EA)와 액체 및 고체 상태 cross polarization magic angle spinning(CP/MAS) nuclear magnetic resonance spectroscopy(NMR)법을 사용하여 분석하였다. 실리카 표면에 BTPED 를 도입하는 반응은 1시간 내에, BTPED로 개질된 실리카의 N-H기에 대한 AHM의 acrylate기와의 마이클 부가 반응에 따른 methacrylate기 도입은 2시간 내에 반응이 각각 완결됨을 확인하였다. 또한 BTPED로 개질된 실리카에 대하여 투입되는 AHM의 몰 비가 증가할수록 N-H기와 acrylate기의 마이클 부가 반응으로 인한 methacrylate기의 도입이 증가하였으며 이는 AHM을 도입했을 때 나타나는 FTIR 스펙트럼의 C=O 피크 면적 변화로 확인하였다. 위의 결과를 EA 및 고체 상태 $^{13}C$ 및 $^{29}Si$ NMR 분석으로도 확인하였다.

• Journal of Korean Neurosurgical Society
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• 제30권sup1호
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• pp.51-54
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• 2001

Objective : Authors analyzed clinical outcomes of cranioplasty according to the materials used for covering defects of the skulls. Methods : From January 1997 to February 2000, there were forty one patients undergone cranioplasty at our institution. We used refrigerated autogenous bone flaps in 19 cases(group A) and methyl methacrylate(MMA) in 22 cases(group B). The medical records and plain skull radiographs of the patient were reviewed. Results : There were thirty men and eleven women. Mean follow up period was 12 months(From operation to last Outpatient department follow up). The mean operative time of the group A($136.8{\pm}3$ minutes) was shorter than the group B($172.7{\pm}2$ minutes, Mann-Whitney test, p=0.001). In group A, the degree of satisfaction was good in 8 cases, fair in 10, and poor in 1. In the group B, there were fair in 13 and poor in 9. So the cosmetic result was superior in the group A(Chi-square test, p=0.00). The complications were occured in one case of flap infection in the group A and 6 in the group B(one stitch abscess, 4 infected flaps, one subgaleal hematoma). Conclusion : Cranioplasty using refrigerated autogenous bone flap showed shorter operative time, better cosmetic results, and less complication rate than those using MMA.

• Restorative Dentistry and Endodontics
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• 제40권1호
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• pp.23-29
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• 2015

Objectives: The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods: Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens ($1.0{\times}1.0mm$), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Results: Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05). However, it was not significantly different from Pre-etching/Silorane and Methacrylate groups. Conclusions: Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

• 폴리머
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• 제29권5호
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• pp.463-467
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• 2005

Fluoroalkyl methacrylate, 아크릴산, 2-hydroxyethyl methacrylate(HEMA)를 공중합한 불소화 아크릴계 이온성 고분자로 제조한 이온성 고분자-백금 복합재료(IPMC)의 구동력을 증대시키기 위하여, HEMA의 OH기를 1,3-diethoxy-1,1,3,3-tetramethyldisiloxane으로 가교하였다. 가교반응에 의하여 IPMC의 수분흡수가 감소하면서, 기계적 강도, 구동력이 증가함을 관찰하였다. 그러나 IPMC의 구동성, 즉 외부 전위에 의한 변위와 전류량은 가교에 의해 감소하였다.