• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.35-42
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• 2014

Thermal analysis properties and adhesive properties of self-healing agents were evaluated through differential scanning calorimetry, reaction heat measurement, and adhesive shear test. D1E0, D3E1, D1E1, D1E3, and D0E1, depending on the mixing ratio of DCPD and ENB, were considered as self-healing agents. The amount of Grubbs' catalyst, depending on the type of self-healing agents, was varied from 0.1 wt% to 1.5 wt%. In the case of DCPD, the polymerization reaction occurred faster and the stabilized adhesive strength increased as the amount of catalyst increased; however, a large amount of catalyst was required. ENB had excellent reactivity with a small amount of the catalyst; however, high reaction heat was observed at the early stage of polymerization. Thermal analysis properties and adhesive properties of self-healing agents can be controlled by varying a mixing ratio of DCPD and ENB. Among the self-healing agents used for this study, the D3E1 would be one of the most preferable candidates with regard to maximum adhesive strength, reaching time to maximum adhesive strength, stabilized adhesive strength, and reaction heat.

• Polymer(Korea)
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• v.37 no.3
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• pp.356-361
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• 2013

Microcapsules of two different self-healing agents, 5-ethylidene-2-norbornene (ENB) and ENB with a crosslinker, surrounded by a melamine-urea-formaldehyde shell were manufactured. In this work, a red dye was incorporated into the self-healing agents as a tracer for better visual observations. It revealed that the incorporation of a red dye into self-healing agents did not disturb the formation of microcapsules from the examination of thermal resistance, particle size/size distribution and morphology of the resulting microcapsules. Releasing of self-healing liquid into the induced crack from ruptured microcapsules and filling between crack planes were observed using an optical microscope. Also observed was the reaction of filled healing agent with embedded Grubbs' catalyst in an epoxy coating layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.435-436
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• 2006

This study focused on the introduction of the self healing technique for polymeric composites and evaluated the healing efficiency by the use of the interlaminar toughness fracture test. The DCPD (dicyclopentadiene) and ENB (5-ethylidene-2-norbornene) were used for the healing agent and the Grubbs' catalyst was used for the catalyst. According to the results, healing efficiency was found to be 37.9%, 22.3%, 26.3%, 22.8%, 30.8%, 30.8%, 33.0%, 33.4% for mode II fraction of 0%, 20%, 35%, 50%, 65%, 80%, 90%, 100%, respectively.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.88-92
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• 2004

In this study; a series of 2',4'-doubly branched carbocyclic nucleosides (8,9,10) were synthesized from simple acyclic ketone derivative as starting material. The installation of the 4'-quaternary carbon needed was carried out using a 〔3,3〕-sigmatropic rearrangement. In addition, the introduction of a methyl group in the 2'-position was accomplished by Grig-nard reaction. Bis-vinyl was successfully cyclized using a Grubbs' catalyst II. The natural bases (adenine, cytosine, uracil) were efficiently coupled with the use of a Pd(0) catalyst. Although all the synthesized compounds were assayed against several viruses, only cytosine analogue 9 showed weak antiviral viral activity (EC$_{50}$=45.4 $\mu$M) against CoxB3 virus.s.

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1812-1816
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• 2004

The stereoselective synthesis 4′,6′-dually branched carbocyclic nucleosides was accomplished in this study. The introduction of a methyl group in the 6′$({\alpha})$-position was accomplished by Felkin-Anh controlled alkylation. The construction of the required 4′$({\alpha})$-quaternary carbon was carried out using a [3,3]-sigmatropic rearrangement. Bis-vinyl 6 was successfully cyclized using a Grubbs' catalyst II. The natural bases (adenine, cytosine) were efficiently coupled using a Pd(0) catalyst. When the synthesized compounds were examined for their activity against several viruses such as the HIV-1, HSV-1, HSV-2 and HCMV, the cytosine analogue 13 exhibited good antiviral activity against the HCMV.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.262-265
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• 2004

This study focused on the introduction of the self-healing technique for polymeric composites and evaluated the healing efficiency through the interlainar fracture toughness tests. The DCPD and ENB were used for a healing agent and the Grubbs' catalyst as a catalyst. The healing efficiency was evaluated by the use of mode I and the mode n fracture toughnesses. According to the results, the DCPD-ENB mixture with a suitable ratio revealed better healing efficiency than DCPD only.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1520-1524
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• 2005

This paper describes the racemic and stereoselective synthetic route for a novel 4'$\alpha$-phenyl and 6'$\alpha$-methyl doubly branched carbocyclic nucleosides from an acyclic 2-hydroxy acetophenone. The installation of phenyl group at the 4'-position of carbocyclic nucleoside was successfully accomplished via a sequential [3,3]-sigmatropic rearrangement. The stereoselective introduction of a methyl group in the 6'$\alpha$-position was accomplished by Felkin-Anh controlled alkylation. Bis-vinyl 11 compound was successfully cyclized using a Grubbs’ catalyst II to desired carbocycles. The natural bases (adenine and cytosine) were efficiently coupled using a Pd(0) catalyst. Although all the synthesized compounds were examined for their activity against several viruses such as HIV-1, HSV-1, HSV-2 and HCMV, only cytosine analogues 17 exhibited weak antiviral activity against HCMV.

• YAKHAK HOEJI
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• v.49 no.1
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• pp.20-24
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• 2005

The synthesis of 4',5'-doubly branched carbocyclic nucleosides was accomplished in this study. The selective methylation in the 5'-position was made by Felkin-Anh controlled Grignard addition. The construction of the required 4'-quaternary carbon was carried out by using a [3,3]-sigmatropic rearrangement. Bis-vinyl 6 was successfully cyclized using a Grubbs' catalyst II. The natural pyrimidine bases (cytosine, uracil, thymine) were efficiently coupled using a Pd(0) catalyst. When the synthesized compounds were examined for their activity against several viruses such as the HIV-1, HSV-1, HSV-2 and HCMV, the cytosine analogue 13 exhibited weak antiviral activity against the HCMV.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1545-1548
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• 2007

This paper discusses the racemic and stereoselective synthetic route for novel 4'α -methyl and 6'α -methyl analogues of abacavir. The quaternary carbon at the 4'-position of carbocyclic nucleoside was installed successfully via a Claisen rearrangement. The stereocontrolled construction of a methyl group in the 6'α - position was directed through the Felkin-Anh rule. A Bis-vinyl compound 9 was cyclized successfully using Grubbs' catalyst II to provide a carbocycle nucleus for the target compound. The synthesized compound 15 showed moderate anti-HIV activity (EC50 = 10.67 μM, MT-4 cell lines).

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.266-269
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• 2004

In this study, bond strengths for the self-healing agents were evaluated through the modified lap shear test in order to suggest the optimal healing conditions for the repair of polymeric composites. The healing agents of DCPD, ENB, and their mixtures were activated with Grubbs' catalysts. According to the results, the mixture of DCPD and ENB gave better opportunity than DCPD only due to the rapid acivation with catalyst in view of the economic and practical use.