Durable Fluoroalkyl-Modified MXene Coatings with Integrated Superhydrophobic, Photothermal, and Anti- Icing Properties

Linh Ngoc To 과학기술연합대학원대학교 한국생산기술연구원(KITECH) 2025 국내석사

Ice accumulation possesses serious challenges across infrastructure, transportation, and industry. Therefore, robust multifunctional coatings exhibiting inhibition of ice formation and facilitation of ice removal is necessary to be developed for practical applications. This study presents the synthesis, modification, and evaluation of fluoroalkyl-functionalized MXene coatings with superior anti-icing, de-icing and photothermal properties. The modified MXene material (MX-Fx), where x is the feeding ratio of fluoroalkyl silane (1H,1H,2H,2H-perfluorodecyltrimethoxysilane, FAS-17) for coatings was obtained via selective etching of the Al from Ti3AlC2 MAX phase and subsequent delamination using tetramethylammonium hydroxide, followed by surface modification with FAS-17. Al plates were used for base substrates and PDMS was coated on the plates as an adhesive primer. Then MX-Fx particles were sprayed on to the PDMS-coated Al substrates. The incorporation of fluoroalkyl groups substantially improved hydrophobicity, with MX-F20 achieving a water contact angle of ~170° and a roll-off angle of 4°, attributed to its hierarchical micro/nanostructure and low surface energy. Photothermal experiments under simulated sunlight confirmed that MX-Fx coatings, particularly MX-F20, exhibited rapid and stable light-to-heat conversion, reaching 72 ℃ within 10 min at 25 ℃ and maintaining elevated temperatures even under subzero conditions. The coatings showed excellent thermal cycling stability across multiple on/off irradiation cycles. Anti-icing performance was significantly enhanced. At −10 ℃, MX-F20 delayed water droplet freezing for up to 2485 s which is much longer than those of bare Al (10 s) and PDMS coating (25 s). The coating also enabled efficient solar-driven de- icing, melting frozen droplets in 545 s. Ice adhesion strength was notably reduced, with MX-F20 showing an ice adhesion strength of 86.6 kPa, facilitating passive ice removal with minimal force. Durability tests demonstrated resistance of the MX-F20 coating to environmental stress, including chemical immersion (pH 1, pH 14, and 3.5% NaCl), UV exposure, sand abrasion, and water droplet impact. MX-F20 maintained its superhydrophobic performance under all conditions, indicating strong chemical, mechanical, and photochemical stability. Overall, MX-F20 integrates effective superhydrophobicity, efficient photothermal conversion, and strong environmental resilience, making it a promising candidate for anti-icing and de-icing applications in aviation, energy infrastructure, and other cold-climate technologies. Key words: MXene, surface modification, photothermal, anti-icing, de-icing. * A thesis submitted to committee of the University of Science and Technology in a partial fulfillment of the requirement for the degree of Master of Engineering/Master of Science conferred in August 2025 저온 환경에서의 얼음 축적은 인프라, 운송, 산업 전반에 걸쳐 심각한 문제를 초래한다. 따라서 실제 응용에 적합한 얼음 형성 억제 및 제거 기능을 동시에 갖춘 견고한 다기능 코팅의 개발이 필수적이다. 본 연구에서는 우수한 방빙, 제빙, 광열 특성을 갖는 플루오로알킬기로 기능화된 맥신 코팅의 합성, 표면 개질 및 성능 평가를 수행하였다. FAS- 17 (1H,1H,2H,2H-퍼플루오르데실트리메톡시실란)의 도입 비율(x)에 따라 명명된 MX-Fx 코팅은 Ti3AlC2 의 MAX 상으로부터 Al 을 선택적으로 제거한 후, 테트라메틸암모늄 하이드록사이드를 이용한 박리 과정을 거쳐 제조되었으며, 이후 FAS-17 로 표면을 개질하였다. Al 판을 기재로 사용하고, 접착력 확보를 위해 PDMS 를 프라이머로 도포한 후, 그 위에 MX-Fx 입자를 분사하여 코팅하였다. 플루오로알킬기의 도입은 표면의 저에너지 특성과 계층적 마이크로/나노 구조에 의해 소수성을 크게 향상시켰으며, MX-F20 은 약 170°의 접촉각과 4°의 구름각을 나타내었다. 모사 태양광 하에서 수행된 광열 실험 결과, 특히 MX-F20 은 빠르고 안정적인 빛-열 변환 특성을 보였으며, 25 ℃ 에서 10 분 이내에 72 ℃ 에 도달하였고, 영하의 온도 조건에서도 높은 온도를 유지하였다. 반복적인 온/오프 조사 실험에서도 우수한 열적 안정성을 확인하였다. 방빙 성능 역시 현저히 향상되었으며, –10 ℃ 에서 MX-F20 은 물방울의 결빙을 최대 2485 초까지 지연시켰다. 이는 베어 알루미늄(10 초), PDMS 코팅(25 초)에 비해 크게 향상된 수치이다. 또한 태양광을 이용한 제빙 실험에서는 545 초 내에 얼음 제거가 가능하였다. MX-F20 의 얼음 부착 강도는 86.6 kPa 로 크게 감소되어, 최소한의 힘으로 수동적 제빙이 가능함을 보여주었다. 내구성 시험 결과, MX-F20 코팅은 산/염기(pH 1, pH 14), 염수(3.5% NaCl), 자외선 조사, 모래 충격, 물방울 충격 등 다양한 환경 스트레스에 대해 우수한 저항성을 보였으며, 모든 조건에서 초소수성을 유지하였다. 결론적으로, MX-F20 은 효과적인 초소수성, 뛰어난 광열 변환 효율, 탁월한 내환경성을 통합한 코팅재로서, 항공, 에너지 인프라, 한랭 지역 기술 분야에서 방빙 및 제빙 응용을 위한 유망한 후보로 평가된다. 주요단어(Key words) : 맥신, 표면 개질, 광열, 방빙, 제빙.

Joint Modeling of Thin-walled Beam Structures for Fast Concept Designs Considering Higher-order Deformations

NGUYEN NGOC LINH 세종대학교 대학원 2020 국내박사

Development of Ni doped CuWO4 thin films for photoelectrochemical water oxidation : 광전기화학적 물 산화를 위한 Ni doped CuWO4 박막 개발

Tran, Thi Ngoc Linh Postech University of Science and Technology 2014 국내석사

CuWO4 is a promising material in solar water oxidation owing to a suitable band gap for visible-light absorption as well as high stability. With a view to improving its activities, we tried to introduce impurities into the host lattice and recognized Ni as the best dopant to others. Polycrystalline Ni doped CuWO4 with various ratios were synthesized to examine the photocatalytic conversion capability. Spray pyrolysis was employed to fabricate the thin films onto FTO glasses at a fixed condition of temperature, flow rate, pressure of carrier gas and distance between the spray gun and substrates. Material characteristics were identified by X-ray diffraction (XRD) and X-ray spectroscopy (XPS). Those spectra reveal that nickel atoms were successfully inserted into copper vacancies of the host lattice without any segregation of the dopant phase. UV-vis absorbance measurements demonstrate negligible influence of Ni on CuWO4 since all spectra have similar curves, suggesting a preliminary band gap of 2.3 eV. Photoelectrochemistry of pristine and Ni doped CuWO4 with various target ratios was performed under solar simulation with neutral condition afforded by a 0.1M potassium phosphate (KPi). 1% Ni doped samples presented the highest photocurrent densities in either linear sweep voltammetry (LSV) or bulk electrolysis, which are twice performances of bare CuWO4. Furthermore, its steady-state photocurrent increased gradually by 15.89% after 1 hour illuminated while performances of other samples stayed the same. Oxygen and hydrogen evolutions were employed to examine photocatalytic water reaction of Ni doped CuWO4. Faradaic efficiencies are ca. 76.8% and 82.7% for oxygen and hydrogen generation rates, respectively. To elucidate the reasons of such upgraded performances, we borrowed two diagnostic investigations. Incident photon-to-current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) measurements conducted under the same condition revealed pertinent trends with photoactivities, perfectly showing origin of enhancements. In case of 1% Ni doped CuWO4, doubled IPCE represented improved solar conversion. Meanwhile, its resistance accomplished from EIS was reduced two times. Due to decrease in charge-transfer resistance at the interface of the semiconductor and electrolyte, recombination possibility was eliminated across the bulk, hence increased solar conversion and photocatalytic performances.

Preparing Asian American Leaders in Higher Education: An Exploration Study Using Bronfenbrenner's Ecological Model

Nguyen, Linh Ngoc ProQuest Dissertations & Theses University of Sout 2022 해외박사(DDOD)

This study uses Bronfenbrenner's Ecological Systems Theory to examine Asian American academic leaders' under-representation in higher education through personal influences and influences in the immediate and distal environments. The purpose of this study is to explore the career trajectories of Asian American faculty in the context of environmental influences that either supported or hindered them from advancing to academic leadership positions. The study was designed to address two research questions: (1) What perceived influences in the Asian American faculty's immediate environment support or hinder their professional advancement? (2) What perceived influences in the Asian American faculty's distal environment support or hinder their professional advancement? The study employed a qualitative phenomenological method and conducted an online interview with 10 Asian American academic leaders. As a result, the themes emerged, focusing solely on the participants' cultural identity, self-efficacy, networking, mentorship, professional development, and organizational support. The study discussed and presented implications for personal and institutional practices, policies, and recommendations for future research.

Spatially Controlled Organic/Inorganic Hybrids Designed to Enhance Cellular Response

Luong, Linh Ngoc University of Michigan 2011 해외박사(DDOD)

Bone is a complex organ that serves many functions. However, in cases of trauma, congenital malformations, and skeletal disorders, impaired healing occurs. Bone tissue engineering is an alternative to conventional therapies such as bone grafting. The work presented in this dissertation involves the development of a bone engineering approach whereby coprecipitation, a biomimetic strategy to precipitate bone-like apatite onto a biomaterial, is used to incorporate biomolecules in a spatially-controlled manner. The global hypothesis was that the coprecipitation of biomolecules with apatite can enhance cell response compared to adsorption, specifically: (1) enhancing transfection efficiency by coprecipitating DNA-lipoplexes with apatite and (2) enhancing osteogenic differentiation by coprecipitating multiple growth factors in a spatially controlled manner within apatite. Coprecipitation spatially localized protein within apatite and allowed for higher protein retention compared to adsorption. Applying these advantages towards gene delivery, the coprecipitation of DNA-Lipoplexes transfected cells with a higher efficiency compared to adsorption and polymer incorporation methods. To provide the design criteria for a multiple growth factor delivery system to better mimic in vivo conditions, BMP-2 and FGF-2 were chosen due to their roles in osteogenesis. The concentrations and sequence of BMP-2 and FGF-2 had significant effects on osteogenic differentiation of BMSCs cultured on TCPS, with low concentrations of FGF-2 enhancing DNA content, and high concentrations of BMP-2 enhancing osteogenesis. Delivery of FGF-2 followed by BMP-2 or delivery of BMP-2 followed by BMP-2 and FGF-2 enhanced osteogenic differentiation compared to simultaneous delivery. For the hybrid delivery system, the individual release profiles of BMP-2 and FGF-2 were significantly affected by the concentration used during coprecipitation. Utilizing coprecipitation to control BMP-2 and FGF-2 localization within apatite to mimic the sequential exposure required by BMSCs, minimal effects on DNA and osteogenic differentiation were demonstrated. The presence of mineral may have delayed or inhibited osteogenic response with a possible compensation upon sequential delivery. These organic/inorganic delivery systems have the potential of delivering multiple biomolecules to better mimic spatiotemporal gradients in the in vivo environment. Utilizing this novel approach to better simulate the cellular environment by manipulating interfaces can facilitate the development of multiple tissue systems.

Empirical studies on corporate capital structure in Vietnam

Linh, Doan Ngoc Duy Soongsil University 2015 국내박사