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dc.description.abstractWith recent developments in nanoscience, carbon-based nanomaterials such as fullerenes, nanotubes, and nanodiamonds (NDs) are currently attracting considerable attention. Among these nanomaterials, NDs offer unique physical features such as transparency, super hardness, chemical stability, high conductivity, and biocompatibility. Despite having such excellent features, NDs aggregate easily during synthesis and when they are added to a medium. Therefore, it is necessary to develop methods such as surface modification to prevent ND aggregation. In this study, in order to disperse ND in aqueous and non-aqueous media, we achieved surface modification and solubilization of ND powder with mean sizes of 5 nm and 60 nm. Powder X-Ray diffraction (powder-XRD) and transmission electron microscopy (TEM) were used to observe the size and diffraction patterns of pristine ND. Surface functionalized ND was observed by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and dynamic light scattering (DLS). We demonstrated that surface functionalized ND remains stable and dispersive in various media and it can be applied as a nanocomposite material in fields such as medicine, biology, and nanocomposite materials. Based on previous results, we incorporated surface functionalized ND to various polymers as a source of reinforcement for polymer composite materials. Unlike pristine NDs, surface functionalized NDs were expected to improve physical and chemical properties of nanocomposite. We selected polycarbonate (PC) and polymethyl methacrylate (PMMA) as polymer substrates and blended them to derive benefits from both. The polymer nanocomposites dispersed with the ND ranging from 1 to 10% in content were subjected to the measurements of surface morphology, friction coefficient, wear resistance, and calorimetry. In comparison to composite films that incorporated pristine ND, composite films with surface functionalized ND had a higher friction coefficient and exhibited improved wear resistance. These results could be verified by morphological observations by AFM and TEM. Based on the results obtained for polymer nanocomposite films, we prepared nanocomposite coatings using various coating materials such as polyisoprene, Na2SiO3, polyurethane, varnish, epoxy, and silicon. The nanocomposite coatings were dispersed with the ND ranging from 1 to 10% in content. From the results of tribological observations, it was found that nanocomposite coatings that contained surface functionalized ND exhibited improved wear resistance, up to 9 times better than that in coatings containing pristine ND. Polyisoprene coating had the highest friction coefficient, while silicon coating had the lowest value. These results also agreed with the AFM and TEM morphological results. Surface functionalized NDs interacted strongly with polymer substrates, thus enhance physical and chemical properties of nanocomposites. Those properties depend on polymer compositions, functional group, and ND contents. Therefore, by controlling and optimizing these factor, nanocomposites dispersed with surface functionalized NDs can be applied in various fields.;최근의 나노 과학의 발전으로 탄소로 구성되어있는 fullerene, 나노튜브, 나노다이아몬드 등의 나노 물질이 큰 주목을 받고 있다. 이러한 나노 물질 중에서도 나노다이아몬드는 투명성, 초강도성, 화학적 안정성, 높은 전도성, 생체 적합성 등의 진기한 물리적인 특성을 갖고 있다. 하지만 이러한 뛰어난 특징에도 불구하고, 합성과정이나 매체에 첨가를 할 때에는 쉽게 뭉쳐지려는 경향이 있다. 그러므로 이러한 나노다이아몬드의 뭉침 현상을 방지하기 위하여 표면 처리 방식 등의 방법이 도입되어야 한다. 본 연구에서는 수용액과 비수용액에서의 나노다이아몬드의 분산을 위하여 5 nm 와 60 nm의 사이즈를 갖고 있는 나노다이아몬드에 표면처리를 하였다. Powder XRD와 TEM을 통하여 pristine 나노다이아몬드의 사이즈와 diffraction 패턴을 관찰하였다. 표면 처리된 나노다이아몬드를 FTIR, AFM, DLS를 통해 관찰함으로써 다양한 매질에서 안정하고 분산능력이 뛰어난 것을 관찰하였다. 그러므로 의약, 생물, 고분자 복합체로의 적용이 가능하다는 것을 보여준다. 앞선 결과를 바탕으로 표면 처리된 나노다이아몬드를 고분자 복합체의 강화를 목적으로 첨가하였다. 이 실험에서 polycarbonate(PC)와 polymethyl methacrylate(PMMA)를 폴리머로 선택했고, 이 두 폴리머의 장점을 결합하고자 PC와 PMMA를 혼합한 폴리머를 만들었다. 고분자 복합체에 나노다이아몬드를 1-10%으로 조절하여 첨가하였고, 완성된 고분자 복합체 필름의 표면형상, 마찰계수, 표면 저항력, 열량측정 등을 하였다. Pristine 나노다이아몬드를 첨가한 고분자 복합체와 비교하여 봤을 때 표면 처리된 나노다이아몬드를 첨가한 고분자 복합체는 마찰 계수와 표면 저항력이 증가된 것을 보였다. 이러한 결과는 표면 형상을 관찰한 AFM과 TEM으로부터 입증할 수 있었다. 고분자 복합체의 결과를 바탕으로 polyisoprene, Na2SiO3, polyurethane, varnish, epoxy, silicon을 코팅제로 사용한 코팅 복합체를 제조하였다. 코팅 복합체에 나노다이아몬드를 1-10%으로 조절하여 첨가하였다. 마찰공학적 결과에 따르면 polyisoprene 코팅제의 마찰계수가 가장 크고, 실리콘 코팅제는 가장 작은 값을 나타냈다. 또한 표면 처리된 나노다이아몬드를 첨가한 복합체의 표면저항력이 pristine 나노다이아몬드가 첨가된 복합체보다9배나 증가한 것을 알 수 있다. 이러한 결과로 보아 표면 처리한 나노다이아몬드를 첨가한 복합체에서는 pristine 나노다이아몬드를 첨가한 복합체에 비해 복합체의 물리적·화학적 성질을 증진시켜줌을 알 수 있다. 증진된 특성들은 폴리머의 종류, 기능집단, 나노다이아몬드의 양에 따라 달라지므로 여러 요소들을 잘 제어함으로써 다방면으로 응용 가능함을 제시한다.-
dc.description.tableofcontentsAbstract = x Ⅰ. Introduction = 1 Ⅱ. Experimental section = 5 Ⅱ-1. Materials = 5 Ⅱ-2. Sample preparation = 5 Ⅱ-2-1. Preparation of surface functionalized nanodiamonds = 5 Ⅱ-2-2. Preparation of polymer nanocomposite films = 7 Ⅱ-2-3. Preparation of nanocomposite coatings = 7 Ⅱ-3. Measurements = 9 Ⅱ-3-1. Characteriziation of surface functionalized nanodiamonds = 9 Ⅱ-3-2. Morphological and tribological characteristic of polymer nanocomposite = 9 Ⅱ-3-3. Thermogravimetric (TG) analysis = 10 Ⅱ-3-4. Morphological tribological characteristics of nanocomposite coatings = 10 Ⅲ. Results and Discussion = 11 Ⅲ-1-1. Identification of pristine NDs = 11 Ⅲ-1-2. Observations of surface functionalized NDs = 17 Ⅲ-1-3. Morphological character and size distribution of surface functionalized ND = 20 Ⅲ-1-4. Surface electric properties of surface functionalized ND = 26 Ⅲ-1-5. Solubility of surface functionalized NDs = 29 Ⅲ-2. Polymer nanocomposite containing surface functionalized NDs = 31 Ⅲ-2-1. Wear variations of functionalzied ND in polymer films = 31 Ⅲ-2-2. Thermalgravimetry analysis of polymer nanocomposite films = 39 Ⅲ-2-3. Surface morphology of polymer nanocomposite films = 42 Ⅲ-3. Nanocomposite coatings containing surface functionalized NDs = 46 Ⅲ-3-1. Wear variation of nanocomposite coatings = 46 Ⅲ-3-2. Surface morphology of nanocimposite coatings = 51 Ⅳ. Conclusion = 55 Ⅴ. References = 57 Abstract (in Korean) = 61-
dc.format.extent15265946 bytes-
dc.publisher이화여자대학교 대학원-
dc.titlePolymer composites dispersed with surface-functionalized nanodiamonds-
dc.typeMaster's Thesis-
dc.title.translated표면 기능화 나노다이아몬드를 함유한 고분자 복합체-
dc.creator.othernameJee, Ah-young-
dc.format.pagexii, 63 p.-
dc.identifier.major대학원 화학·나노과학과- 8-
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