STM Study of 2-Mercaptoethanol Self-Assembled Monolayer on Au(111)

현문섭,이충균,Hyeon, Mun Seop,Lee, Chung Gyun Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.2

Presented are the STM images of self-assembled monolayer of 2-mercaptoethanol on Au(111). Striped structures of ($6{\times}3_{\frac{1}{2}}$), ($5{\times}3_{\frac{1}{2}}$), ($4{\times}3_{\frac{1}{2}}$) and compact-($5{\times}3_{\frac{1}{2}}$) were observed after annealing at $80^{\circ}C.$ Analysis of the ordered structures revealed that the basic fundamental units of the ordered structures were three crystallographically non-equivalent ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, and that the way of combination of the assemblies produced the four different structures. The($6{\times}3_{\frac{1}{2}}$) structure ( $\theta$ = 0.33) was composed of one ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$)$R30^{\circ}$ assembly, while the ($5{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.30) and ($4{\times}3_{\frac{1}{2}}$) ( $\theta$ = 0.38) structures were consisted of two ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies, separated by 5a and 4a, respectively. Furthermore, the compact-(5X 3½) structure ( $\theta$ = 0.50) was obtained by overlapping three ($3_{\frac{1}{2}}{\times}3_{\frac{1}{2}}$) $R30^{\circ}$ assemblies. In spite of the diversity in the adsorption structures, all the adsorption sites of 2-mercaptoethanol were fundamentally identical. On the other hand, the unannealed primitive SAM of 2-mercaptoethanol was characterized by two observations: a short-range order keeping the adsorbed molecules at approximately $3_{\frac{1}{2}}$ a and the small domains of the striped structures supporting that the observed surface structures on the annealed surface were the extension of the primitive layer of 2-mercaptoethanol. Comparing these observations with the already published structures of ethanthiol, it was concluded that the interaction between the hydroxyl groups of 2-mercaptoethanol might play a significant role in the adsorption step of 2-mercaptoethanol on Au(111) to organize the adsorption structures different from those of ethanthiol.

Surface-Grafted Rodlike Polymers: Adaptive Self-Assembled Monolayers and Rapid Photo-Patterning of Surfaces

Han, Mingu,Rahman, M. Shahinur,Lee, Jae-Suk,Khim, Dongyoon,Kim, Dong-Yu,Park, Ji-Woong American Chemical Society 2011 Chemistry of materials Vol.23 No.15

<P>We present a new concept of functionalizing solid surfaces using polymeric self-assembled monolayers (PSAM) that are obtained by grafting onto solid surfaces an asymmetric block copolymer composed of a long rodlike block and a short surface-reactive block. Poly(n-hexylisocyanate)-<I>b</I>-poly[3-(trimethoxysilyl)propyl methacrylate] (PHIC-<I>b</I>-PTMSM) is synthesized via a living anionic polymerization and an atom transfer radical polymerization. The new rod–coil block copolymer forms a polymeric self-assembled monolayer (PSAM) through covalent bonding of the sticky PTMSM block and planar adsorption of PHIC rodlike chains onto the substrate surface. The uniform PSAM with a thickness identical to the diameter of the rodlike chain is produced by the immersion coating method in a range of immersion solution concentrations and coating times. The PSAMs present unique properties thanks to the freedom of rotation of the end-grafted rodlike chains. The PSAMs exhibit nematic liquid crystalline ordering when the monolayer is fluidized by solvent vapor. A mixed SAM with a nanodot pattern is obtained by introducing a second coating agent of octadecyltrimethoxysilanes (ODTMS) onto the PSAM-coated substrate. The PSAM is micropatternable using photochemical cleavage of the anchoring blocks by brief exposure to UV. Use of the PSAMs as an additional dielectric layer in P3HT-based field effect transistors (FETs) is also demonstrated.</P><P>Rodlike polymers are covalently tethered to the surface to yield a polymeric self-assembled monolayer (PSAM). Thanks to noncovalent adsorption of planar rods, the PSAMs exhibit unique properties such as liquid crystalline order, the reactivity toward an additional surface-modifying agent to generate a mixed SAM, and the capability of photochemical patterning.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2011/cmatex.2011.23.issue-15/cm201138u/production/images/medium/cm-2011-01138u_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm201138u'>ACS Electronic Supporting Info</A></P>

XPS와 AFM에 의한 올리고펩타이드의 자기 집합화 단분자막 분석

송성훈,박진영,김우식,Nakamura, Chikashi,Miyake, Jun,장상목 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.1

금속 기판 위에 유기 박막을 형성하는 방법 중에서 티올기와 Au와의 결합을 이용한 자기집합에 관한 연구가 활발히 진행되고 있다. 포르피린 유도체와 강하게 결합하는 타올기를 가지는 올리고펩타이드 PSP1과 PSP2를 합성하여 MOPS 완층용액에서 금표면에 자기집합화 단분자막(self-assembled monolayer, SAM)을 형성시켜 X-ray photoelection spectroscopy(XPS)와 atomic force microscopy(AFM)을 이용하여 분석하였다. 그 결과 PSP2의 경우와 PSP1의 경우보다 Au표면에서 SAM이 더욱 더 잘 형성되고 있음을 알 수 있었고 MOPS완충용액에 존재하는 황 이온의 영향도 알 수 있었다. 이 결과는 구성단위로부터 이론적으로 계산한 SAM막의 steric energy 값의 차이에서 유추한 결론과 일치하였다. Recently, the self-assembled monolayer(SAM) of thiols on nible metals has been studied intensively. Oligopeptides such as PSP1(Tyr-Ala-Gly-Tyr-Cys) and PSP2(His-Ala-Ser-Cys) with thiol group, which interact strongly with a typical cationic porphyrin derivative, are synthesized. Peptides adsorption from the liquid phase on Au has been studied using X-ray photoelection spectroscopy(XPS) and AFM image. XPS provides further evidence that the primary adsorbate species is bonded to Au through the sulfur atom. By the analysis of XPS spectra and AFM image, it is found that PSP2 is self-assembled better than PSP1 and the sulfur ion MOPS buffer solution has an effect on the self-assembling performance. This result is coincident with the calculation result of steric energies of Au-Peptide bonded SAM structure.

Effect of self-assembled monolayer and aluminum oxide ALD film on a PMMA substrate

신소라,박종완 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.6

The antireflective (AR) coated poly methyl methacrylate (PMMA) substrate was deposited by atomic layer deposition (ALD)on a self-assembled monolayer (SAM) to improve hydrophobicity and mechano-chemical properties of organic thin films. Thewater contact angles (WCA) were tested to characterize the surface wettability of SAM octadecyltrichlorosilane (OTS) films. Results showed that a contact angle of 105.9 o was obtained for the SAM films with an annealing process, and the highest WCAof 120° was achieved for the films prepared by the SAM and ALD multi-process. The surface morphology of the SAM filmswith different assembly times and varying number of ALD cycles was obtained by atomic force microscopy (AFM). Themaximum light transmittance for the SAM films on the PMMA substrate reached 99.9% at a wavelength of 450 nm. It wasfound that the SAM surfaces were not affected at all by the ALD process.

유기 디스플레이 소자를 위한 Self Assembled Monolayer의 표면개질을 이용한 ITO의 일함수 증가

지승현,김수호,고재환,윤영수,Jee Seung-Hyun,Kim Soo-Ho,Ko Jae-Hwan,Yoon Young-Soo 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.6

Indium tin oxide (ITO) used as an electrode in organic light emitting diodes (OLEDs) and organic thin film transistors (OTFTs) was modified by a self-assembled monolayer (SAM). For device fabrication, surface of the ITO was modified by immersion in a solution including various phosphonic acid at room temperature in order to increase work function of an electrode. The work function of ITO with SAM was measured by Kelvin probe. Work function increase of 0.88 eV was observed in ITO with various SAM. Therefore, ohmic contact is achieved in an interface between ITO and organic semiconductors (pentacene). We analyzed the origin of work function increase of ITO with SAM by X-ray photoelectron spectroscopy. We confirmed that increase of oxygen bonding energy attributed to increase the work function of ITO. These results suggested that ITO with the SAM gives a high possibility for high performance of OLEDS and OTFTs.

Electrocatalytic Behavior of Self-assembled Monolayer of a Novel Tetraazamacrocyclic Copper(II) Complex in Ascorbate Oxidation

Soo-Kyoung Kim,박원철,Dongyeol Lim,Hun-Gi Hong* 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.6

Hyperthermal Collision-induced Dissociation of Bromotoluene Radical Cations at Self-Assembled Monolayer Surfaces

( Sung-chan Jo ),( Rodinei Augusti ),( R. Graham Cooks ) 한국질량분석학회 2011 Mass spectrometry letters Vol.2 No.1

Hyperthermal ion/surface collisions of bromotoluene radical cations were studied using perfluorinated (F-SAM) and hydroxyl-terminated (OH-SAM) self-assembled monolayer surfaces in a tandem mass spectrometer with BEEQ geometry. The isomers were differentiated by ion abundance ratios taken from surface-induced dissociation (SID). The dissociation rate followed the order of ortho > meta > para isomers. The peak abundance ratio of m/z 51 to m/z 65 showed the best result to discern the isomers. A dissociation channel leading to tolylium ion was suggested to be responsible for the pronounced isomeric differences. The capability of SID to provide high-energy activation with narrow internal energy distribution may have channeled the reaction into the specific dissociation pathway, also facilitating small differences in reaction rates to be effective in the spectral time window of this experiment. All of the molecular ions experiencing reactive collisions with the F-SAM surface undergo transhalogenation, in which a fluorine atom on the surface replaces the bromine in the incoming ions. This reactive collision was dependent on the laboratory collision energy occurring in ca. 40.75 eV range.

Preparation of hydrophobic self-assembled monolayers on paper surface with silanes

Oh, M.J.,Lee, S.Y.,Paik, K.H. Korean Society of Industrial and Engineering Chemi 2011 Journal of industrial and engineering chemistry Vol.17 No.1

This study was conducted to obtain hydrophobic self-assembled monolayers on paper surface with silanes by a simple and facile method in the vapor or solvent phase. Filter papers with water contact angle over 120<SUP>o</SUP> were successfully prepared under sufficient reaction time and silane concentration, and their hydrophobic properties were evaluated by the contact angle measurement and stockigt size test. And the effect of SAM-formation on mechanical properties of paper like wet tensile strength and PPS roughness was also presented. Results from the study reveal the effective reaction time and silane concentration to form stable SAM depending on the coating method and the silane treatments. The fabrication of self-assembled monolayers on the surface of the papers with silanes proved to be a simple process for the preparation of the superhydrophobic papers.

Self-Assembled Monolayer Modified MoO3/Au/MoO3 Multilayer Anodes for High Performance OLEDs

정대균,Chefwi Lim,김명기,정경훈,김재헌,김지영,박진구,민경식,이재갑 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.1

We control the work function and the surface energy of the MoO3/Au/MoO3 (MAM) anode of OLEDs by modifying the top MoO3 layer viavapor phase deposition. The performance and stability of the device aresignificantly altered depending on the dipole direction of the selfassembledmonolayer (SAM) with permanent dipole moment insertedbetween N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB)film and a MAM anode as well as on the interfacial wetting between theSAM and NPB layer. A CF3-terminated monolayer on a MAM electrodeimproved the performance and stability of the OLEDs relative to areference device with only a MAM electrode, demonstrating that coatingwith SAMs via vapor phase deposition is an effective method to engineerthe interface of MAM electrode optoelectronic devices.

Tribological behaviors of self-assembled 3-aminopropyltriethoxysilane films on silicon

Gu Qinlin,Cheng Xianhua 한국물리학회 2008 Current Applied Physics Vol.8 No.5

3-Aminopropyltriethoxysilane (APTES) thin films were prepared on the hydroxylated silicon substrate by a self-assembling process from formulated solution. Chemical compositions of the films were detected by X-ray photoelectron spectrometry (XPS). The thickness of the films was determined with an ellipsometer, while the morphologies of the original and worn surfaces of the samples were analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The tribological properties of APTES thin films sliding against GCr15 steel ball were evaluated on a UMT-2MT reciprocating friction and wear tester. It was found that the macroscopic friction coefficients for coating times more than 1 h ranged from 0.177 to 0.3 whereas the value for short coating time was as high as 0.8. It was also found that the tribological behaviors of APTES films were sensitive to normal load and sliding velocity. SEM observation of the morphologies of worn surfaces indicates that the wear of silicon is characteristic of brittle fracture and severe abrasion. Differently, abrasion and micro-crack dominate the wear of APTES–SAM. The superior friction reduction and wear resistance of APTES films compared to the silicon substrate are attributed to good adhesion of the films to the substrate. 3-Aminopropyltriethoxysilane (APTES) thin films were prepared on the hydroxylated silicon substrate by a self-assembling process from formulated solution. Chemical compositions of the films were detected by X-ray photoelectron spectrometry (XPS). The thickness of the films was determined with an ellipsometer, while the morphologies of the original and worn surfaces of the samples were analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The tribological properties of APTES thin films sliding against GCr15 steel ball were evaluated on a UMT-2MT reciprocating friction and wear tester. It was found that the macroscopic friction coefficients for coating times more than 1 h ranged from 0.177 to 0.3 whereas the value for short coating time was as high as 0.8. It was also found that the tribological behaviors of APTES films were sensitive to normal load and sliding velocity. SEM observation of the morphologies of worn surfaces indicates that the wear of silicon is characteristic of brittle fracture and severe abrasion. Differently, abrasion and micro-crack dominate the wear of APTES–SAM. The superior friction reduction and wear resistance of APTES films compared to the silicon substrate are attributed to good adhesion of the films to the substrate.