폴리비닐알코올 스펀지의 표면 개질을 통한 나노영가철의 부착성 향상

김영화,서영교,김효원,황유훈 대한환경공학회 2019 대한환경공학회지 Vol.41 No.9

Objectives : Nanoscale zero-valent iron (nZVI) is known to effectively remove various contaminants due to its small size and high specific surface area, but it is limited in practical water treatment processes due to its difficulty in recovery after use. In this study, a method of immobilizing nZVI on a support material was adopted in order to increase the applicability of nZVI. A polyvinyl alcohol sponge (PVA), which is readily available commercially, was used as a support. For the immobilization of nZVI, it was considered that improving the binding force with the support is essential in order to enhance the pollutant removal efficiency and prevent nZVI loss. A series of surface modification methods with acrylic acid to induce the formation of carboxyl groups were used to improve the bonding strength with the support. Methods : A PVA sponge with a porosity of 90%, an average pore size of 130 μm, and an apparent density of 0.082 g/cm3 was used as a supporting material to immobilize nZVI. The PVA sponge was further cut into cubes of 0.3 × 0.3 × 0.3 cm3 for easy handling. The PVA sponge induced an acrylic acid polymer on the surface through the reaction of acrylic acid and potassium permanganate (PVA-AA). We optimized the conditions in a series of steps to synthesize nZVI on PVA-AA. The conditions considered were the mass ratio of Fe2+ and PVA, Fe2+ adsorption time, and the reduction time using NaBH4. A SEM/EDS analysis was performed to monitor the morphology of the synthesized nZVI on PVA-AA. The reduction reactivity was evaluated through nitrate reduction. Results and Discussion : The amount of Fe2+ adsorption of the support material modified with AA (PVA-AA) was superior to that of the unmodified material (PVA), and the time to reach the adsorption equilibrium was shortened to 30 min. The optimum mass ratio was Fe/PVA-AA = 1. These results indicate that carboxyl groups are formed on the surface of PVA by surface modification using AA and that these carboxyl groups induce strong binding affinity toward iron. The SEM/EDS analysis results showed that AA polymer was formed on the surface of the PVA sponge fiber through AA modification. Moreover, a large amount of nZVI was formed on AA modified PVA (PVA-AA). As the reduction time was increased from 0.5 h to 1 h, the distribution of nZVI iron on the surface and inside the support was more uniform. Finally, the reducing reactivity was evaluated through a nitrate reduction experiment. The reduction efficiency and the reduction rate of PVA-AA-nZVI were 1.9 times and 3.5 times higher than those of PVA-nZVI, respectively. Conclusions : A surface modification technology was developed to enhance nZVI immobilization on a commercially available supporting material. Through the modification of acrylic acid on the surface of a PVA sponge, which can be easily obtained on the market, it was possible to increase the attachment efficiency of nZVI by forming a large number of carboxyl groups on the surface, and subsequently higher pollutant reduction efficiency could be obtained. It is expected that both the economic efficiency and the ability to remove contaminants can be improved by the development of a material having an increased amount of nZVI by the surface modification technology developed in this study. 목적 : 본 연구에서는 나노 영가철의 적용성을 높이기 위하여 지지체 소재에 고정화하는 방법을 택하였으며, 시중에서 쉽게 구할 수 있는 폴리비닐알코올 스펀지(PVA)를 지지체로 사용하였다. 나노 영가철을 고정화시키는 데 있어서 지지체와의 결합력을 향상시키는 것은 오염물질 제거 효율 증대 및 나노 영가철의 탈리를 방지하는 측면에서 중요하다고 판단하였다. 지지체와의 결합력을 향상시키기 위하여 PVA 표면을 아크릴산으로 개질하여 카르복실기를 유도하는 일련의 표면 개질 방법을 사용하였으며, 이를 통하여 나노 영가철 입자의 부착이 향상되는지 여부에 대하여 평가하였다. 방법 : 나노 영가철을 고정하기 위한 담체로써 공극률 90%, 평균 공극 크기 130 μm, 겉보기 밀도 0.082 g/cm3의PVA 스펀지를 사용하였으며, 취급에 용이하도록 0.3 × 0.3 × 0.3 cm3의 정육면체로 가공 후 사용하였다. PVA 스펀지는 아크릴산 및 과망간산칼륨과의 반응을 통하여 표면에 아크릴산 고분자를 유도하였다(PVA-AA). PVA-AA에 나노 영가철을 합성하기 위한 일련의 과정에서의 조건들을 최적화하였다. 고려한 조건은 나노 영가철의 전구 물질인Fe2+와 PVA의 질량 비율, Fe2+ 흡착 시간 및 NaBH4를 이용한 환원 시간이었다. PVA-AA의 Fe2+ 흡착량, 나노 영가철 합성 이후 SEM/EDS 분석을 실시하였으며, 질산성 질소 환원 실험을 통하여 환원 반응성을 평가하였다. 결과 및 토의 : AA로 개질된 지지체 소재(PVA-AA)의 Fe2+ 흡착량이 미개질 소재(PVA)의 경우보다 우수함을 확인할 수 있었고, 흡착 평형에 이르는 시간도 30분으로 단축되는 것을 확인할 수 있었다. 최적 질량 비율은Fe/PVA-AA = 1이었다. 이와 같은 결과는 AA를 이용한 표면 개질을 통하여 PVA 표면의 카르복실기를 형성하였고, 형성된 카르복실기가 철과의 강한 상호 결합을 유도하기 때문인 것으로 파악되었다. SEM/EDS를 통하여 분석한 결과, AA 개질을 통하여 PVA 스펀지 섬유 표면에 AA 고분자가 형성된 것을 확인할 수 있었고, 여기에 나노영가철이 결합된 형태를 확인하였다. AA 개질을 통하여 다량의 나노 영가철이 결합된 것을 확인하였으며, 환원시간을 0.5시간에서 1시간을 늘림에 따라 나노 영가철의 표면과 내부에서의 분포가 더욱 균일해지는 것을 확인할수 있었다. 최종적으로 질산성 질소 환원 실험을 통하여 환원 반응성을 평가하였으며, 표면 개질을 수행하였던PVA-AA-nZVI가 표면 개질을 수행하지 않은 PVA-nZVI에 비하여 환원 효율은 1.9배, 환원 속도는 3.5배 더 높은것으로 나타났다. 결론 : 나노 영가철의 단점을 개선하고 활용성을 높이기 위해 지지체를 활용함에 있어 부착성을 향상시키기 위한표면 개질 기술을 개발하고자 하는 목적으로 수행되었다. 시중에서 쉽게 구할 수 있는 PVA 스펀지 표면을 아크릴산을 개질함을 통하여 표면에 카르복실기를 다수 형성하여 나노 영가철의 부착 효율을 증대시킬 수 있었고, 더 높은 오염물질 환원 효율을 얻을 수 있었다. 영가철이 고정된 소재의 오염물질 환원율을 높이기 위해 중요한 인자는영가철의 함량이라고 할 수 있다. 담체 표면을 개질하고 합성하는 과정으로 영가철의 합성량을 높인 소재의 개발로실제 공정에 적용함에 있어 경제성과 오염물질의 제거 능력 모두 향상시킬 수 있을 것으로 기대된다.

One‐Step Multipurpose Surface Functionalization by Adhesive Catecholamine

Kang, Sung Min,Hwang, Nathaniel S.,Yeom, Jihyeon,Park, Sung Young,Messersmith, Phillip B.,Choi, Insung S.,Langer, Robert,Anderson, Daniel G.,Lee, Haeshin WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.14

<P><B>Abstract</B></P><P>Surface modification is one of the most important techniques in modern science and engineering. The facile introduction of a wide variety of desired properties onto virtually any material surface is an ultimate goal in surface chemistry. To achieve this goal, the incorporation of structurally diverse molecules onto any material surface is an essential capability for ideal surface modification. Here, a general strategy for surface modification is presented in which many diverse surfaces can be functionalized by immobilizing a wide variety of molecules. This strategy functionalizes surfaces by a one‐step immersion of substrates in a one‐pot mixture of a molecule and a catecholamine surface modification agent. This one‐step procedure for surface modification represents a standard protocol to control interfacial properties.</P>

Zwitterionic sulfobetaine polymer-immobilized surface by simple tyrosinase-mediated grafting for enhanced antifouling property

Kwon, H.J.,Lee, Y.,Phuong, L.T.,Seon, G.M.,Kim, E.,Park, J.C.,Yoon, H.,Park, K.D. Elsevier BV 2017 ACTA BIOMATERIALIA Vol.61 No.-

Introducing antifouling property to biomaterial surfaces has been considered an effective method for preventing the failure of implanted devices. In order to achieve this, the immobilization of zwitterions on biomaterial surfaces has been proven to be an excellent way of improving anti-adhesive potency. In this study, poly(sulfobetaine-co-tyramine), a tyramine-conjugated sulfobetaine polymer, was synthesized and simply grafted onto the surface of polyurethane via a tyrosinase-mediated reaction. Surface characterization by water contact angle measurements, X-ray photoelectron spectroscopy and atomic force microscopy demonstrated that the zwitterionic polymer was successfully introduced onto the surface of polyurethane and remained stable for 7days. In vitro studies revealed that poly(sulfobetaine-co-tyramine)-coated surfaces dramatically reduced the adhesion of fibrinogen, platelets, fibroblasts, and S. aureus by over 90% in comparison with bare surfaces. These results proved that polyurethane surfaces grafted with poly(sulfobetaine-co-tyramine) via a tyrosinase-catalyzed reaction could be promising candidates for an implantable medical device with excellent bioinert abilities. Statement of Significance: Antifouling surface modification is one of the key strategy to prevent the thrombus formation or infection which occurs on the surface of biomaterial after transplantation. Although there are many methods to modify the surface have been reported, necessity of simple modification technique still exists to apply for practical applications. The purpose of this study is to modify the biomaterial's surface by simply immobilizing antifouling zwitterion polymer via enzyme tyrosinase-mediated reaction which could modify versatile substrates in mild aqueous condition within fast time period. After modification, pSBTA grafted surface becomes resistant to various biological factors including proteins, cells, and bacterias. This approach appears to be a promising method to impart antifouling property on biomaterial surfaces.

An approach for multi-patch surface modification with a curve constraint satisfying convergent G1 continuity

Luong Quang-Phap,Nam Jong-Ho,Le Tat-Hien 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.5

Conceptual shape design plays a critical role in determining the appearance and functionality of a product. Currently, computer-aided design systems can represent a complex shape through multiple surface patches; however, the methods used for multi-patch surface modification are still limited and counterintuitive. There is an ongoing need for more intuitive and efficient surface modification tools that allow designers to directly control shape changes through specific constraints while maintaining surface quality. In this paper, we propose an intuitive modification approach based on the designer’s activity to interactively manipulate a multi-patch surface with an arbitrary curve constraint with tangent continuity (G1) across connected B-spline patches. The advantages of the curve and surface superposition were used to change the shape of the surface. The first step was a shape-control mechanism that used shape functions to control the deformation of a superposed surface. A fine-tuning step was followed to ensure the aesthetic requirements and quality of the surface by achieving convergent G1 continuity in a linear manner. The efficiency and practicality of the proposed approach have been verified using application examples. The proposed approach can be applied to modify surfaces used in the design of a complex geometric model.

플라즈마 표면처리가 표면에너지와 Cr코팅층 / 기판의 부착 특성에 미치는 영향

김동용 ( Dong Yong Kim ),정은욱 ( Eun Wook Jeong ),후이 ( Kwun Nam Hui ),최영선 ( Young Son Choe ),한정호 ( Jung Ho Han ),조영래 ( Young Rae Cho ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.10

Atmospheric plasma surface treatment (APST) was applied on the soda-lime glass and silicon wafer(Si-wafer) substrates for surface modification. The surface energy for the surface treated samples was measured using the wetting angle. The effect of APST on surface energy and interface properties between sputtered chromium (Cr) coatings and substrates was investigated. The surface energy increased linearly and reached a maximum value of 74 mJ/m2 by APST. The increase in surface energy is due to the increased value of the polar component in surface energy. When the samples were exposed to the air, the increased surface energy decreased and tended to have hydrophobicity. The work of adhesion for the surface treated samples was calculated using the data of surface tension for water. We demonstrated that the trend of work of adhesion for the samples was similar to the change of adhesion strength between sputtered Cr coatings and the surface treated substrates. (Received March 13, 2013)

Enhancement of thermal conductivity of BN/epoxy composite through surface modification with silane coupling agents

Jang, Inseok,Shin, Kyung-Ho,Yang, Il,Kim, Hyeon,Kim, Juseong,Kim, Wan-Ho,Jeon, Sie-Wook,Kim, Jae-Pil Elsevier 2017 Colloids and surfaces. A, Physicochemical and engi Vol.518 No.-

<P><B>Abstract</B></P> <P>The thermal conductivity of boron nitride/epoxy composite was increased by up to 45.4% through surface modification of BN. The silane coupling agents with different main carbon chain (C3 and C16) were introduced on the BN surface through sol-gel reaction to improve the affinity of BN with epoxy resin. The surface-modified BN exhibits the higher dispersibility in epoxy than as-prepared BN. In the case of the modified BN samples, the dispersion was more stable as increasing the length of carbon main chain of silane. It means that the higher interfacial adhesion of BN/epoxy composite could be obtained by introducing the longer carbon chain on BN surface. Using the surface modification, the thermal conductivity of the treated BN with HDTMS reached to 3.49W/mK through decrease of the thermal contact resistance at the BN/epoxy interface. As a result, the enhancement of thermal conductivity could be controlled by varying the surface property of BN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The surface of Boron nitride (BN) was modified with different silanes in order to control the BN surface property. </LI> <LI> The affinity of BN with epoxy resin was effectively improved as increasing the carbon chain length of silane, resulting in the increment of adhesion BN/epoxy. </LI> <LI> The enhancement of thermal conductivity of BN/epoxy composite could be successfully achieved by decreasing the thermal contact resistance at the BN/epoxy interface. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic illustration for the mechanism of surface modification of BN with silane.</P> <P>[DISPLAY OMISSION]</P>

Nanostructured β-type titanium alloy fabricated by ultrasonic nanocrystal surface modification

Kheradmandfard, Mehdi,Kashani-Bozorg, Seyed Farshid,Kim, Chang-Lae,Hanzaki, Abbas Zarei,Pyoun, Young-Shik,Kim, Jung-Hyong,Amanov, Auezhan,Kim, Dae-Eun Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>The surface of β-type Ti-Nb-Ta-Zr (TNTZ) alloy, which is a promising material for biomedical applications, was treated with the ultrasonic nanocrystal surface modification (UNSM) technique to enhance its hardness. As a result, a gradient nanostructured (GNS) layer was generated in the surface; the microstructure of the top surface layer consisted of nanoscale lamellae with a width of about 60–200nm. In addition, there were lamellar grains consisting of nanostructured subgrains having unclear and wavy boundaries. The treated surface exhibited a hardness value of ∼385HV compared to 190HV for the untreated alloy. It was further determined that highly dense deformation twins were generated at a depth of ∼40–150µm below the UNSM-treated surface. These deformation twins led to a significant work hardening effect which aided in enhancing the mechanical properties. It was also found that UNSM treatment resulted in the formation of micropatterns on the surface, which would be beneficial for high bioactivity and bone regeneration performance of TNTZ implants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UNSM is a method that utilizes ultrasonic vibration to generate nanostructured surface. </LI> <LI> The surface of β-type Ti-Nb-Ta-Zr (TNTZ) alloy was treated with the UNSM technique. </LI> <LI> A gradient nanostructured layer was generated in the surface. </LI> <LI> Top surface layer consisted of nanoscale lamellae with a width of about 60–200nm. </LI> <LI> Hardness of treated surface was ∼385HV compared to 190HV for the untreated alloy. </LI> </UL> </P>

양이온성 고분자전해질로 표면개질된 셀룰로오스 나노피브릴의 내첨처리에 따른 종이의 강도 및 탈수성 분석

김경민,이지영,조해민,김수호,김철환 한국펄프·종이공학회 2019 펄프.종이기술 Vol.51 No.4

In this study, we evaluated the effect of the surface-modified cellulose nanofibril (CNF) on the strength, drainage, and retention of the specialty paper made from cotton lint mixed pulp (CLMP). The surface modification of CNF was conducted via enzymatic hydrolysis and homogenization using cationic polyacrylamide (C-PAM) to yield enzyme (EN)-CNF. C-PAM was added into a 0.5% CNF slurry for 5 min at 600 rpm. After performing surface modification, the viscosity, particle size, and fiber width of the unmodified and surface-modified CNFs were measured. Further, handsheets were produced by adding CNF or EN-CNF into the CLMP furnish. The drainage rate and chemical oxygen demand of the CLMP furnish were determined to evaluate the effect of surface modification on the drainability and retention in the wet-end part. There were no significant differences in terms of the viscosity, particle size, and fiber width when comparing unmodified and surface-modified CNFs. The surface-modified CNF handsheets exhibited higher tensile strength and folding endurance when compared with those exhibited by the unmodified CNF handsheets. Additionally, surface modification increased the drainage rate and decreased the COD of the CLMP furnish. Therefore, the surface modification of CNF positively affected the specialty paper in terms of strength, drainage, and retention.

초음파 나노표면개질기술의 특성과 활용방안 연구

편영식(Youngsik Pyoun),박정현(Jeonghyeon Park),조인호(Inho Cho),김창식(Changsik Kim),서창민(Changmin Suh) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.3

All the failure in fatigue of torsion, bending and rolling contact, and in sliding wear begins mostly from surface. So much efforts have been invested to the surface technology which deal these problems during past decades, but the industrial demand keeps growing and more significant requirements are added to researchers and engineers. Nano crystal surface modification technology which makes the surface layers into nano crystalline, induces big and deep compressive residual stress, increases surface hardness, improves surface hardness, and make micro dimples structure on surface is an emerging technology which can break limits of current surface technology and relieve the burden of researchers and engineers. In this study, a nano crystal surface modification technology which is calling UNSM(Ultrasonic nano crystal surface modification) technology, is introduced and how it has been applied to industry to solve these failure problems is explained.

Application of ultrasonic nanocrystal surface modification for improving surface profile of DEDed AISI 316L

김민섭,조영관,박상후,심도식 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

This study investigated the effect of ultrasonic nanocrystal surface modification (UNSM) on the deteriorated surface of AISI 316L deposited using the direct energy deposition (DED) technology. After UNSM treatment, the coarse DEDed surface was fined, and a regular micro-surface profile was implemented. Compared to the case before UNSM treatment, the waviness and roughness of the surface after UNSM treatment decreased by up to 73.8 % and 86.2 %, respectively, and reduced further as the UNSM interval was decreased. Surface severe plastic deformation (S 2 PD) was induced in the dendrite structure of the UNSM-treated DEDed sample surface. The microstructure was deformed till a depth of up to 92.13 mm from the surface and was significantly affected by the interval. After UNSM treatment, the hardness improved by up to 71.5 % and gradually decreased from the surface to the inside; the hardness was improved by UNSM up to a maximum depth of 400 μm. Although the UNSM interval condition had a significant effect on the DEDed surface, it barely affected the relationship between the directions of DED deposition and UNSM treatment. This study confirmed that the UNSM technology can effectively improve a DEDed surface.